CN107817422A - A kind of faulty line search localization method and system - Google Patents

Abstract

The invention relates to a method and system for searching and locating faulty lines, including: dividing the distribution network into levels, determining the levels of each line in the distribution network; determining each level according to the installation position of the protection device on each line Corresponding cutting surface; according to the cutting surface, the synchronous output line current of each protection device and the preset differential protection criterion, the distribution network is searched vertically and horizontally through the dichotomy method to complete the search and location of the faulty line. The present invention divides the entire distribution network into levels, determines the cutting plane corresponding to each level, and adopts the search mode of dichotomy to conduct longitudinal search and horizontal search, which can continuously reduce the fault search area, greatly reduce the search calculation amount, and improve the search speed , so as to realize the rapid search and location of the fault line.

Description

A method and system for searching and locating a faulty line

technical field

The invention relates to the technical field of relay protection, in particular to a fault line search and location method and system.

Background technique

The traditional step-by-step current protection (stage III) has the advantages of simple setting and wiring and high economy, and is widely used in distribution networks. However, as the scale of the distribution network continues to expand, the structure and operation mode become more and more complex, a series of problems such as protection setting coordination and long backup protection action time have caused a certain impact on the safe and stable operation of the power grid.

In recent years, wide-area protection based on wide-area information has received extensive attention. As the most ideal protection principle, differential protection judges whether an internal fault occurs by evaluating the balance of the current at each end of the protected component. It is known as a fast protection with absolute selectivity. The introduction of wide-area information provides the basis for the realization of wide-area differential protection, using the obtained wide-area multi-point information to judge faults inside and outside the area. Wide-area current differential protection can not only provide differential main protection with fast action speed, but also provide differential backup protection with small action delay and good selectivity for adjacent areas, with excellent performance. Traditional wide-area protection can be divided into centralized and distributed architectures according to the configuration perspective. With the continuous improvement of computer and other hardware processing capabilities, system redundancy design can also be guaranteed accordingly. From the perspective of overall performance, adopting a centralized architecture is undoubtedly an excellent choice. With the development of wide-area communication network and the advancement of synchronous measurement technology, in the near future, it is possible for the intelligent protection center to simultaneously obtain the synchronous information of all nodes in the entire network within the time frame of rapid protection actions.

However, if there are too many branch lines in the regional distribution network under the jurisdiction of the protection intelligence center, when all the line current measurement phasors are collected into the protection intelligence center at the same time in a very short period of time, although its data processing ability has been improved to a certain extent, it is still Will face the challenge of massive information processing. When the serial processing method is used to perform traversal troubleshooting and search for each line in the area, although the time for a single fault search is relatively short, due to the large number of lines in the entire area, the time required to complete the fault search for the entire area Calculation delay cannot be ignored. In fact, it is this problem that restricts the development of centralized wide-area protection. In addition, considering the distribution network powered by a single power supply, it is usually only equipped with a measurement protection unit on the side of the line power supply. For this type of current mainstream distribution network, it is impossible to obtain the current at both ends of the line required for the differential current. For power distribution Therefore, it is necessary to design an algorithm with absolute selectivity and fast search ability to improve the performance of distribution network protection.

Contents of the invention

The invention provides a method and system for searching and locating a faulty line, which is used to solve the problem that the current distribution network cannot obtain the current at both ends of the line to perform corresponding differential protection judgments and perform a large number of differential judgments at the same time, which will result in a long calculation process The problem of delay.

The technical solution of the present invention to solve the above-mentioned technical problems is as follows: a method for searching and locating a faulty line, comprising the following steps:

Step 1. Carry out hierarchical division of the distribution network, and determine the hierarchy of each line in the distribution network;

Step 2. Determine the cutting surface corresponding to each level according to the installation position of the protective device on each line;

Step 3. According to the cutting surface, the line current synchronously output by each of the protection devices and the preset differential protection criterion, the distribution network is sequentially searched vertically and horizontally by dichotomy to complete the search and location of the faulty line .

The beneficial effects of the present invention are: divide the whole distribution network into levels, determine the cutting plane corresponding to each level; meanwhile, obtain the synchronous output line current of each protection device according to the wide-area information. Use the cutting surface and the line current output by each line protection device to search and judge whether there is a fault in the line according to the differential protection criterion. In the process of differential search and judgment, the search mode of dichotomy is used for longitudinal search And lateral search to determine the fault line. Through this method of fault line search, the fault search area can be continuously narrowed, the amount of search calculations can be greatly reduced, and the search speed can be improved, so as to realize rapid search and location of fault lines.

On the basis of the above technical solutions, the present invention can also be improved as follows.

Further, said step 1 includes:

Step 1.1, determining the main line in the distribution network, and marking the main line as a first-level line;

Step 1.2, determining each branch on the bus connected to the main line, and marking each branch as a second-level line;

Step 1.3. Determine the branches of the same-level line, and mark the branches of the same-level line as the next-level line corresponding to the same-level line;

Step 1.4, according to the number of layers of the last layer line, determine the maximum number of layers of the distribution network;

Step 1.5, based on the current number of levels of each terminal line, expand the layers of each terminal line to the level corresponding to the maximum number of levels, wherein the expanded number of levels is the maximum number of levels and the current level number difference.

Further, the cutting surface corresponding to each level passes through the ends of the protective devices on all lines in the level;

Then said step 3 includes:

Step 3.1, according to the search area of the distribution network, determine its corresponding first level and last level;

Step 3.2, according to the line current synchronously output by each of the protection devices, respectively determine the cutting current on the cutting plane corresponding to the first level and the last level;

Step 3.3, according to the cutting current, calculate the cutting current variation and cutting current braking amount corresponding to the search area;

Step 3.4, judging whether there is a fault in the search area according to the variation of the cutting current, the braking amount of the cutting current and the preset differential protection criterion;

Step 3.5, if yes, judge whether the search area contains only one level, if yes, perform step 3.6, if not, divide the search area vertically into two new search areas by dichotomy, and respectively divide the search area into two new search areas Perform step 3.1 for two new search areas;

Step 3.6, judging whether the search area contains only one line, if so, determine that this line is a faulty line, and complete the search and location of the faulty line, if not, according to the first line and the last line in the search area, use the dichotomy method to divide The search area is horizontally divided into two new search areas, and step 3.1 is performed on the two new search areas respectively.

Further, the cut current variation The cutting current braking amount The preset differential protection criterion is expressed as: in, Expressed as the cutting current corresponding to the first level, Expressed as the cutting current corresponding to the last level, k is expressed as the braking coefficient;

Then the step 3.4 includes: judging whether the preset differential protection criterion is established according to the variation of the cutting current, the braking amount of the cutting current and the braking coefficient, and if so, judging the search area failure.

Further, the cutting current is expressed as: the sum of the current vectors output by the protection devices on each line cut by a cutting plane, wherein the corresponding cutting current on each expansion level of each terminal line is the same and is the same as that before the expansion. Line current output by a protective device on a terminal line.

In order to solve the technical problem of the present invention, a fault line search and location system is also provided, including:

A hierarchy division module, configured to divide the distribution network into levels and determine the levels of each line in the distribution network;

A cutting surface determining module, configured to determine the cutting surface corresponding to each level determined by the layer division module according to the installation positions of the protection devices on each line;

A positioning module, configured to sequentially conduct a longitudinal analysis of the distribution network by a dichotomy method according to the cutting plane determined by the cutting plane determination module, the line current synchronously output by each of the protection devices, and the preset differential protection criterion. Search and horizontal search to complete the fault line search and location.

Further, the hierarchical division module is specifically used for:

Determine the main line in the distribution network, and mark the main line as the first-level line; determine the branches on the bus connected to the main line, and mark the branches as the second level Hierarchical lines; determine the branches of the same level of lines, and mark the branches of the same level of lines as the next level of lines corresponding to the same level of lines; according to the number of levels of the last level of lines, determine The maximum number of layers of the distribution network; the current number of layers of each terminal line, respectively expand the layers of each terminal line to the level corresponding to the maximum number of layers, wherein the expanded number of layers is the maximum The difference between the level number and the current level number.

Further, the cutting surface corresponding to each level passes through the ends of the protective devices on all lines in the level;

Then the positioning module is specifically used for:

According to the search area of the distribution network, determine the corresponding first level and the last level; according to the line current synchronously output by each of the protection devices, respectively determine the cutting planes corresponding to the first level and the last level. current; according to the cutting current, calculate the cutting current variation and cutting current braking amount corresponding to the search area; according to the cutting current variation, the cutting current braking amount and the preset differential protection criterion, Judging whether the search area has a fault; if so, judging whether the search area contains only one level; if so, judging whether the search area only contains one line, and if so, determining that the line is a faulty line, and completing the faulty line search Positioning, if not, according to the first line and the last line in the search area, divide the search area horizontally into two new search areas by dichotomy, and determine the corresponding If not, divide the search area vertically into two new search areas by dichotomy, and determine the corresponding first level and last level of the two new search areas respectively.

Further, the cut current variation The cutting current braking amount The preset differential protection criterion is expressed as: in, Expressed as the cutting current corresponding to the first level, Expressed as the cutting current corresponding to the last level, k is expressed as the braking coefficient;

Then, when the positioning module is used to judge whether there is a fault in the search area, it specifically includes: judging the preset differential protection according to the variation of the cutting current, the braking amount of the cutting current and the braking coefficient. Whether the criterion is established, if yes, it is judged that the search area is faulty.

Further, the cutting current is expressed as: the sum of the current vectors output by the protection devices on each line cut by a cutting plane, wherein the corresponding cutting current on each expansion level of each terminal line is the same and is the same as that before the expansion. Line current output by a protective device on a terminal line.

Description of drawings

Fig. 1 is a schematic flow chart of a method for searching and locating a faulty line provided by an embodiment of the present invention;

FIG. 2 is a schematic flowchart of step 110 in a method for searching and locating a faulty line provided by another embodiment of the present invention;

3 is a schematic diagram of fault line classification in a fault line search and location method provided by another embodiment of the present invention;

FIG. 4 is a schematic flowchart of step 130 in a method for searching and locating a faulty line provided by another embodiment of the present invention;

Fig. 5 is a schematic structural diagram of a system for searching and locating a faulty line provided by an embodiment of the present invention.

Detailed ways

The principles and features of the present invention are described below in conjunction with the accompanying drawings, and the examples given are only used to explain the present invention, and are not intended to limit the scope of the present invention.

Embodiment one

A fault line search and location method 100, as shown in Figure 1, includes the following steps:

Step 110, divide the distribution network into levels, and determine the levels of each line in the distribution network.

Step 120, according to the installation positions of the protection devices on each line, determine the cutting plane corresponding to each level.

Step 130 , according to the cutting surface, the line current synchronously output by each protection device and the preset differential protection criterion, sequentially perform longitudinal search and horizontal search on the distribution network by dichotomy to complete the search and location of the fault line.

The purpose of this embodiment is to provide a new algorithm for fast search and location of faulty lines based on wide-area information, to solve the problem that the existing distribution network cannot obtain the current at both ends of the line to make corresponding differential protection judgments and perform a large number of differential protections at the same time. Judgment will generate a long calculation and processing delay problem.

To achieve the above purpose, this embodiment includes: dividing the entire distribution network into levels, and determining the cutting plane corresponding to each level; meanwhile, obtaining the synchronous output line current of each protection device according to the wide-area information. Use the cutting surface and the line current output by each line protection device to search and judge whether there is a fault in the line according to the differential protection criterion. In the process of differential search and judgment, the search mode of dichotomy is used for longitudinal search And lateral search to determine the fault line. Through this method of fault line search, the fault search area can be continuously narrowed, the amount of search calculations can be greatly reduced, and the search speed can be improved, so as to realize rapid search and location of fault lines.

Embodiment two

On the basis of Embodiment 1, as shown in FIG. 2, step 110 includes:

Step 1.1. Determine the main line in the distribution network, and mark the main line as the first-level line.

Step 1.2. Determine each branch on the bus connected to the trunk line, and mark each branch as a second-level line.

Step 1.3: Determine the branch lines branched from the same level line, and mark each branch line branched out from the same level line as the next level line corresponding to the same level line.

Step 1.4. Determine the maximum number of layers of the distribution network according to the number of layers of the last-level lines.

Step 1.5. Based on the current level number of each terminal line, each terminal line level is expanded to the level corresponding to the maximum level number, wherein the expanded level number is the difference between the maximum level number and the current level number.

It should be noted that due to the fact that there are many line branches in the actual distribution network and the wiring is complex, in order to quickly and accurately locate the fault line, the line classification of the distribution network is implemented. When the distribution network is parallel to the main network, the entire network presents a tree-like distribution. In view of the fact that the status of each component in the distribution network is difficult to determine in real time and may change at any time, and the classification of lines is based on the existing network structure, before implementing the fault search, with the help of a reliable state estimation method, dynamically obtain the entire The topology of the distribution network.

After the paired network topology is obtained in real time, the distribution network is classified according to the following principles:

(1) The trunk line is the first level, the branch lines carried on the bus connected to the main line are the second level, the sub-branch lines separated from the branch lines in the same level are the next level lines, and so on. Every time a branch line is divided, the line series will increase by one level. The current transformers at the head ends of all branch lines in the same level line should be concentrated in the same search plane (cutting plane), and each level line corresponds to a corresponding search plane. As the number of lines increases, the number of search planes increases sequentially (I, II, III, ...), and each search plane intersects each branch line in the current level of the line.

(2) Since the distribution network is the power receiving end, in addition to the connection line (the line between the bus bar and the bus bar), the bus bar is generally connected with the terminal line (used to connect the load), which makes it intersect with most of the search areas. The lines are not just the connecting lines, but also various terminal lines. Therefore, it is stipulated that if the current level is a terminal line, the line can be expanded layer by layer to the last level of the network, and in each search plane that the expanded line passes through, the corresponding branch line current is defined as the current of the terminal before expansion. The line currents are the same, and the expanded number of layers is the difference between the maximum number of layers and the current number of layers.

For example, as shown in Figure 3, the arrows in the figure represent the current flow direction, the number 1 represents the power supply, the number 2 represents the main line, the number 3 represents the first bus, the number 4 represents the second bus, and the number 5 represents the load. The line between the two busbars is a branch line, the line between the first busbar and the load 5 is a terminal line, and the line between the second busbar and the load 5 is also a terminal line, and the dotted arcs in the figure represent each cutting plane. Therefore, the main line 2 in the figure is the first level, and the branch lines carried on the above-mentioned first bus 3 connected to the main line 2 are the second level, and the branch lines on the above-mentioned second bus 4 connected with the second level branch line (Terminal line) is the third level. The topology system has three levels in total, and the line connected to the load on the first bus is the second level. Therefore, the second level line is expanded, and the dotted lines in the figure are For the extended line, the line between the first bus bar and the dotted line is the second level, and the dotted line represents the third level.

For another example, a certain distribution network has three busbars, the main line is the first-level line, and the branches on the first bus connected to the main line are the second-level lines, and some of the second-level lines are connected to the next busbar (secondary line) second bus), some branches are directly connected to the load through the terminal line, and the branches on the second bus are all connected to the third bus, then the branches on the second bus are third-level lines, and the branches on the third bus are all connected to the third bus. The terminal line is connected to the load, and the terminal line connected to the branch on the third bus is the fourth-level line. Then, the terminal line connected to the branch on the first bus is first expanded to the third-level line, and then obtained from the extension The third-level line is expanded to the fourth-level line. At this time, the first-level line is the main line, and the second-level line is the branch on the first bus (including the branch connecting the first bus and the second bus and connecting The terminal line of the first bus and load), the third-level line includes the branch on the second bus and the primary extension line extended from the terminal line connecting the first bus and load, and the fourth-level line includes the connection between the third bus and the load The terminal line of the terminal line and the secondary expansion line expanded from the above-mentioned primary expansion line, the number of layers of the terminal line expansion connecting the first bus bar and the load is 4 minus 2.

The line current of the terminal line connecting the first bus bar and the load on the cutting plane where it is delivered, the line current of the primary expansion line on the cutting plane of delivery and the line current of the secondary expansion line on the cutting plane of delivery are the same And are defined as the same terminal line current before expansion.

(3) The terminal line at the last level only uploads the corresponding information to participate in the search for faults at other line levels. For the faults that occur on it, it still relies on the original in-situ protection to cut off, because the protection of the last level line does not need to consider The other protections cooperate so that any fault that occurs on it can be removed without a time limit.

Embodiment three

On the basis of the second embodiment, the cutting surface corresponding to each level passes through the ends of the protective devices on all lines in the level.

Then as shown in Figure 4, step 130 includes:

Step 131, according to the search area of the distribution network, determine its corresponding first level and last level.

Step 132: According to the line current synchronously output by each protection device, respectively determine the cutting currents on the cutting planes corresponding to the first level and the last level.

Step 133 , according to the cutting current, calculate the cutting current change amount and cutting current braking amount corresponding to the search area.

Step 134 , according to the variation of cutting current, the braking amount of cutting current and the preset differential protection criterion, it is judged whether there is a fault in the search area.

Step 135, if yes, judge whether the search area contains only one level, if yes, execute step 136, if not, divide the search area vertically into two new search areas by the dichotomy method, and respectively divide the search area into two new search areas Execute step 131.

Step 136, determine whether the search area contains only one line, if so, determine that this line is a faulty line, and complete the search and location of the faulty line, if not, according to the first line and the last line in the search area, divide the search area horizontally by dichotomy Create two new search areas, and perform step 131 on the two new search areas respectively.

It should be noted that, in the longitudinal search, first determine the cutting current on each cut surface according to the synchronous output line current of each protection device; then conduct a longitudinal search on the distribution network through the dichotomy method according to the cutting surface and cutting current, Determination of faulty levels is done. Then carry out lateral search to this faulty layer, and further locate the faulty line, wherein, first determine the first line and the last line of this layer when lateral search, adopt dichotomy method to divide this layer into two search areas equally (the two The sum of the number of lines in each search area is equal to the number of lines in the faulty search area before bisecting), and then respectively determine the cutting current on each cutting surface for the two search areas and perform fault judgment.

Specifically, the method steps of step 130 are as follows:

S1: According to the search area of the distribution network, determine its corresponding first level and last level;

S2: According to the line current synchronously output by each protection device, determine the first cutting current on the first cutting surface corresponding to the first level and the second cutting current on the second cutting surface corresponding to the last level;

S3: According to the first cutting current and the second cutting current, calculate the cutting current variation and cutting current braking amount corresponding to the search area;

S4: According to the cutting current change amount, cutting current braking amount and preset differential protection criterion, judge whether there is a fault in the search area, if not, end the fault line search and location;

S5: If yes, determine whether the search area contains only one level, if yes, execute S6, if not, divide the search area vertically into two new search areas by dichotomy, and perform steps on the two new search areas respectively S1;

S6: Determine the first line and the last line in the search area, and according to the first line and the last line, divide the search area horizontally into two new search areas by dichotomy;

S7: According to each line current, determine the cutting current on the two cutting surfaces of each new search area, and calculate the cutting current variation and cutting current braking amount corresponding to the new search area according to the cutting current;

S8: According to the preset differential protection criterion, the cutting current change amount and the cutting current braking amount calculated in step S7, judge whether there is a fault in the new search area, if not, end the fault line search and location;

S9: If yes, judge whether the new search area contains only one line, if yes, determine that this line is a faulty line, complete the search and location of the faulty line, if not, execute step S6.

It should be noted that when judging whether the search area contains only one level, although the two cutting planes are located at the two levels respectively, each cutting plane is located at the head end of its corresponding level line (the protective device on each line is located at the head end of the line, and the cutting plane passes through the end of the protection device), therefore, the search area between the two cutting planes contains at least one level, that is, the search area includes all but the last level in the search area other levels.

For example, Step 1: Calculate the cut current of the corresponding search surface. The cutting currents of search plane I and search plane II are respectively: Among them, the currents of each branch have been synthesized into phasors in the corresponding local units, and then uploaded to the intelligent protection center for differential protection judgment.

Step 2: Vertical partition search. The first-level line set and the last-level line set of the searched area correspond to a search surface (cutting surface). Firstly, a vertical partition search is performed on the area between the first and last search surfaces, and the variation and control of cutting current in each area are calculated. Momentum, to see whether it satisfies the fault criterion (differential protection criterion), if it does not meet the criterion, it is considered that the fault occurred outside the jurisdiction of the protection intelligence center, and there is no need for the next fault search in this area; if the criterion is met Criterion, then continue the partition search, the original area will become two new areas, and the total number of line levels in each new area will be reduced by about half. For these two new areas, search according to the above steps respectively, and the fault must exist in one of the areas. For the fault area to be searched, repeat the above process until the number of line levels in this area becomes 1. At this time, the vertical search is terminated, and the fault branch must be located in the last vertical search. The line level between the two search planes superior.

The set representation of vertical partitions: Let i be the first line level number in the area to be searched before partitioning, and n the number of line levels in this area, then the two newly generated areas after a vertical search and partition are

Step 3: Lateral Search. Longitudinal fault search After locating the fault branch on the line level sandwiched by two adjacent search planes, the line level is determined as the horizontal area to be searched, and the horizontal partition search is performed on this area. The search process is the same as the vertical search. When the number of lines in the area to be searched is equal to 1, the faulty line is successfully located, and the horizontal partition search ends, and the faulty line can be located.

The collection representation of the horizontal partition: Let j be the number of the first branch line before the partition of the area to be searched in the horizontal direction, and m be the number of branch lines in the area, then the two newly generated areas after a horizontal search partition are

The purpose of this embodiment is to provide a new algorithm for fast search and location of faulty lines based on wide-area information, to solve the problem that the existing distribution network cannot obtain the current at both ends of the line to make corresponding differential protection judgments and perform a large number of differential protections at the same time. Judgment will generate a long calculation and processing delay problem. To achieve the above purpose, this embodiment includes: dividing the entire distribution network into levels, and determining the cut current composition of different search planes. Use the determined cutting current to calculate the cutting current variation and braking amount of the corresponding search surface, so as to constitute the criterion of differential protection, and use this criterion to judge whether a fault occurs in this area. In the process of differential search and judgment for the whole area, the search mode of dichotomy is used for vertical search and horizontal search to determine the fault line. Through this method of fault line search, the fault search area can be continuously narrowed, the amount of search calculations can be greatly reduced, and the search speed can be improved, so as to realize rapid search and location of fault lines.

Embodiment Four

On the basis of Example 3, the amount of current variation Cutting current braking amount The preset differential protection criterion is expressed as: in, Expressed as the cutting current corresponding to the first level, It is expressed as the cutting current corresponding to the last level, and k is expressed as the braking coefficient.

Then step 134 includes: judging whether the preset differential protection criterion is established according to the cutting current change amount, the cutting current braking amount and the braking coefficient, and if so, judging that there is a fault in the search area.

It should be noted that k is expressed as a braking coefficient, which is usually 0.3 to 0.7.

Embodiment five

On the basis of Embodiment 3 or Embodiment 4, the cutting current is expressed as: the sum of the current vectors output by the protection devices on each line cut by a cutting plane, where the corresponding The cutting current is the same as the line current output by the protective device on the terminal line before expansion.

Embodiment six

A fault line search and location system 200, as shown in Figure 5, includes:

The hierarchy division module is used to divide the distribution network into levels and determine the levels of each line in the distribution network.

The cutting surface determining module is used to determine the cutting surface corresponding to each level determined by the level division module according to the installation positions of the protection devices on each line.

The positioning module is used to conduct longitudinal search and horizontal search on the distribution network sequentially through the dichotomy method according to the cutting surface determined by the cutting surface determination module, the line current synchronously output by each protection device and the preset differential protection criterion, and complete the fault line Search location.

Embodiment seven

On the basis of Embodiment 6, the hierarchical division module is specifically used to: determine the main line in the distribution network, and mark the main line as the first-level line; determine the branches on the bus connected to the main line, and Mark each branch as a second-level line; determine each branch branched from the same level line, and mark each branch branched from the same level line as the next level line corresponding to the same level line; according to the level of the last level line number, to determine the maximum number of levels of the distribution network; root the current number of levels of each terminal line, respectively expand each terminal line layer to the level corresponding to the maximum number of levels, where the expanded number of layers is the maximum number of levels and the current level number difference.

Embodiment eight

On the basis of Embodiment 7, the cut surface corresponding to each level passes through the ends of the protective devices on all lines in the level.

The positioning module is specifically used to: determine the corresponding first level and the last level according to the search area of the distribution network; determine the cutting current on the cutting surface corresponding to the first level and the last level according to the line current synchronously output by each protection device ;According to the cutting current, calculate the cutting current variation and cutting current braking amount corresponding to the search area; according to the cutting current variation, cutting current braking amount and preset differential protection criteria, judge whether there is a fault in the search area; if there is , to determine whether the search area contains only one level; if so, determine whether the search area contains only one line, if so, determine that the line is a faulty line, and complete the search and location of the faulty line, if not, according to the first line and the last line in the search area , divide the search area horizontally into two new search areas by the dichotomy method, and determine the corresponding first level and last level of the two new search areas respectively; if not, divide the search area into two vertically by the bisection method new search areas, and determine the corresponding first level and last level for the two new search areas respectively.

Embodiment nine

On the basis of Embodiment 8, the amount of current variation Cutting current braking amount The preset differential protection criterion is expressed as: in, Expressed as the cutting current corresponding to the first level, It is expressed as the cutting current corresponding to the last level, and k is expressed as the braking coefficient.

When the positioning module is used to judge whether there is a fault in the search area, it specifically includes: judging whether the preset differential protection criterion is established according to the cutting current change amount, the cutting current braking amount and the braking coefficient, and if so, judging whether the search area has a fault. Fault.

It should be noted that k is expressed as a braking coefficient, which is usually 0.3 to 0.7.

Embodiment ten

On the basis of Embodiment 8 or Embodiment 9, the cutting current is expressed as: the sum of the current vectors output by the protection devices on each line cut by a cutting plane, where the corresponding The cutting current is the same as the line current output by the protective device on the terminal line before expansion.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection of the present invention. within range.

Claims (10)

1. A fault line searching and positioning method is characterized by comprising the following steps:

step 1, carrying out hierarchical division on a power distribution network, and determining the hierarchy of each line in the power distribution network;

step 2, determining a cutting surface corresponding to each level according to the installation position of the protection device on each line;

and 3, sequentially carrying out longitudinal search and transverse search on the power distribution network by a bisection method according to the line current synchronously output by the cutting surface and each protection device and a preset differential protection criterion, and completing fault line search and positioning.

2. The method for searching and locating the fault line according to claim 1, wherein the step 1 comprises:

step 1.1, determining a main trunk line in the power distribution network, and marking the main trunk line as a first-level line;

step 1.2, determining each branch on a bus connected with the main line, and marking each branch as a second-level line;

step 1.3, determining each branch circuit separated from the same-level line, and marking each branch circuit separated from the same-level line as a next-level line corresponding to the same-level line;

step 1.4, determining the maximum level number of the power distribution network according to the level number of the last level line;

and step 1.5, respectively expanding the terminal lines to the levels corresponding to the maximum layer levels layer by layer according to the current layer levels of the terminal lines, wherein the expanded layer number is the difference value between the maximum layer levels and the current layer levels.

3. The method for searching and locating the fault line according to claim 2, wherein the cutting surface corresponding to each level passes through the tail ends of the protection devices on all lines in the level;

said step 3 comprises:

step 3.1, determining a corresponding first level and a corresponding last level according to the search area of the power distribution network;

step 3.2, respectively determining cutting currents on cutting surfaces corresponding to the first level and the last level according to line currents synchronously output by the protection devices;

3.3, calculating the cutting current variable quantity and the cutting current braking quantity corresponding to the search area according to the cutting current;

step 3.4, judging whether the search area has faults or not according to the cutting current variable quantity, the cutting current braking quantity and a preset differential protection criterion;

step 3.5, if yes, judging whether the search area only contains one hierarchy, if yes, executing step 3.6, if not, dividing the search area into two new search areas by bisection method, and executing step 3.1 on the two new search areas respectively;

and 3.6, judging whether the search area only contains one line, if so, determining that the line is a fault line, completing fault line search and positioning, otherwise, horizontally dividing the search area into two new search areas by a bisection method according to a first line and a last line in the search area, and executing the step 3.1 on the two new search areas respectively.

4. The method as claimed in claim 3, wherein the variation of the cut current is determined by the search and location methodAmount of the cutting current brakingThe preset differential protection criterion is expressed as:wherein,expressed as the cutting current corresponding to the first level,expressing the cutting current corresponding to the final level, and expressing k as a braking coefficient;

said step 3.4 comprises: and judging whether the preset differential protection criterion is established or not according to the cutting current variation, the cutting current braking amount and the braking coefficient, and if so, judging that the search area has a fault.

5. The method for searching and locating the fault line according to claim 3 or 4, wherein the cutting current is represented as: and the sum of current vectors output by the protection devices on the lines cut by one cutting surface, wherein the corresponding cutting currents on each expansion level of each terminal line are the same and are the line currents output by the protection devices on the terminal line before expansion.

6. A faulty line search positioning system, comprising:

the hierarchical division module is used for carrying out hierarchical division on the power distribution network and determining the hierarchy of each line in the power distribution network;

the cutting surface determining module is used for determining the cutting surface corresponding to each level determined by the level dividing module according to the installation position of the protection device on each line;

and the positioning module is used for sequentially carrying out longitudinal search and transverse search on the power distribution network by a bisection method according to the cutting surface determined by the cutting surface determining module, the line current synchronously output by each protection device and a preset differential protection criterion, so as to complete fault line search positioning.

7. The system according to claim 6, wherein the hierarchical partitioning module is specifically configured to:

determining a main line in the power distribution network, and marking the main line as a first-level line; determining each branch on a bus connected with the main line, and marking each branch as a second-level line; determining each branch circuit separated from the same-level circuit, and marking each branch circuit separated from the same-level circuit as a next-level circuit corresponding to the same-level circuit; determining the maximum level number of the power distribution network according to the level number of the last level line; and respectively expanding the terminal lines to the levels corresponding to the maximum layer levels layer by layer according to the current layer levels of the terminal lines, wherein the expanded number of layers is the difference between the maximum layer levels and the current layer levels.

8. The system for searching and locating the fault line according to claim 7, wherein the cutting surface corresponding to each level passes through the tail end of the protection device on all lines in the level;

the positioning module is specifically configured to:

determining a corresponding first level and a corresponding last level according to the search area of the power distribution network; respectively determining cutting currents on cutting surfaces corresponding to the first level and the last level according to line currents synchronously output by the protection devices; according to the cutting current, calculating cutting current variation and cutting current braking quantity corresponding to the search area; judging whether the search area has a fault or not according to the cutting current variable quantity, the cutting current braking quantity and a preset differential protection criterion; if yes, judging whether the search area only contains one hierarchy; if so, judging whether the search area only contains one line, if so, determining that the line is a fault line, completing fault line search positioning, otherwise, horizontally dividing the search area into two new search areas by a bisection method according to a first line and a last line in the search area, and determining a corresponding first level and a corresponding last level of the two new search areas respectively; and if not, longitudinally dividing the search area into two new search areas by a dichotomy, and respectively determining a corresponding first level and a corresponding last level of the two new search areas.

9. The system for searching and locating a fault line according to claim 8, wherein the amount of change in the cut current is the same as the amount of change in the cut currentAmount of the cutting current brakingThe preset differential protection criterion is expressed as:wherein,expressed as the cutting current corresponding to the first level,expressing the cutting current corresponding to the final level, and expressing k as a braking coefficient;

the positioning module, when being configured to determine whether the search area has a fault, specifically includes: and judging whether the preset differential protection criterion is established or not according to the cutting current variation, the cutting current braking amount and the braking coefficient, and if so, judging that the search area has a fault.

10. The system for searching and locating a fault line according to claim 8 or 9, wherein the cutting current is represented by: and the sum of current vectors output by the protection devices on the lines cut by one cutting surface, wherein the corresponding cutting currents on each expansion level of each terminal line are the same and are the line currents output by the protection devices on the terminal line before expansion.