CN107817422A - A kind of faulty line search localization method and system - Google Patents
A kind of faulty line search localization method and system Download PDFInfo
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- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/08—Locating faults in cables, transmission lines, or networks
- G01R31/081—Locating faults in cables, transmission lines, or networks according to type of conductors
- G01R31/085—Locating faults in cables, transmission lines, or networks according to type of conductors in power transmission or distribution lines, e.g. overhead
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Abstract
The present invention relates to a kind of faulty line search localization method and system, including：Level division is carried out to power distribution network, determines the level of each bar circuit in power distribution network；According to the installation site of the protection device on each bar circuit, cut surface corresponding to each level is determined；According to cut surface, the line current of each protection device synchronism output and default differential protection criterion, longitudinal searching and Horizon Search are carried out successively by dichotomy to power distribution network, complete faulty line search positioning.The present invention carries out level division to whole power distribution network, determine cut surface corresponding to each level, the search pattern for employing dichotomy carries out longitudinal searching and Horizon Search, fault search region can constantly be reduced, greatly reduce search amount of calculation, search speed is improved, realizes that the fast search of faulty line positions with this.
Description
Technical Field
The invention relates to the technical field of relay protection, in particular to a fault line searching and positioning method and system.
Background
The traditional stage type current protection (III stage) has the advantages of simple setting and wiring mode and high economical efficiency, and is widely applied to power distribution networks. However, as the scale of the power distribution network is continuously enlarged, the structure and the operation mode are more and more complex, and a series of problems of setting and matching of protection and long backup protection action time cause certain impact on the safe and stable operation of the power distribution network.
In recent years, wide area protection based on wide area information has received much attention. Differential protection is regarded as the most ideal protection principle, whether internal faults occur or not is judged by evaluating the balance of currents at each end of a protected element, and the protection is known as absolutely selective quick protection. The introduction of wide-area information provides a basis for the realization of wide-area differential protection, and the obtained wide-area multipoint information is utilized to judge the inside and outside of the area of the fault. The wide-area current differential protection not only can provide differential main protection with higher action speed, but also can provide differential backup protection with small action delay and good selectivity for adjacent areas, and has extremely excellent performance. Conventional wide area protection can be divided into two architectures, centralized and distributed, from a configuration perspective. With the continuous improvement of the processing capability of the hardware of the computer, the system redundancy design can be correspondingly ensured, and from the viewpoint of global performance, the adoption of a centralized architecture is undoubtedly an excellent choice. The development of the wide area communication network and the progress of the synchronous measurement technology, in the near future, the protection intelligent center is possible to simultaneously obtain the synchronization information of all nodes of the whole network within the time frame of the rapid protection action.
However, if there are too many branch lines in the distribution network in the area governed by the protection intelligent center, after all the line current measurement phasors are collected to the protection intelligent center at the same time in a very short time, the protection intelligent center will face the challenge of processing massive information despite some improvement in data processing capability. When a serial processing mode is adopted to perform traversal troubleshooting search on each line in an area, although the time consumption of single troubleshooting search is short, due to the fact that a large number of lines exist in the whole area, the calculation delay required for completing the troubleshooting search of the whole area cannot be ignored, and in fact, the problem is that the development of centralized wide area protection is restricted. In addition, considering a power distribution network supplied by a single power supply, a measurement protection unit is usually configured on one side of a line power supply, and for the current mainstream power distribution network, the current at two ends of a line required by differential current cannot be obtained.
Disclosure of Invention
The invention provides a fault line searching and positioning method and system, which are used for solving the problem that the existing power distribution network cannot obtain currents at two ends of a line to carry out corresponding differential protection judgment and simultaneously carry out a large number of differential judgments to generate longer calculation processing time delay.
The technical scheme for solving the technical problems is as follows: a fault line searching and positioning method comprises 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.
The invention has the beneficial effects that: carrying out hierarchical division on the whole power distribution network, and determining a cutting surface corresponding to each hierarchy; and simultaneously, obtaining the line current synchronously output by each protection device according to the wide area information. And searching and judging whether the line has a fault according to a differential protection criterion by using line currents output by the cutting surface and each line protection device, wherein in the differential search judgment process, a dichotomy search mode is adopted to perform longitudinal search and transverse search to determine the fault line. By means of the fault line searching in the mode, the fault searching area can be continuously reduced, the searching calculation amount is greatly reduced, the searching speed is improved, and therefore the quick searching and positioning of the fault line are achieved.
On the basis of the technical scheme, the invention can be further improved as follows.
Further, 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.
Further, 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.
Further, 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;
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.
Further, 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.
In order to solve the technical problem of the present invention, there is also provided a fault line search and location 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.
Further, 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.
Further, the cutting surface corresponding to each level passes through the tail ends of the protection devices 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.
Further, 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.
Further, 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.
Drawings
Fig. 1 is a schematic flowchart of a fault line searching and locating method according to an embodiment of the present invention;
fig. 2 is a schematic flowchart illustrating step 110 of a fault line searching and locating method according to another embodiment of the present invention;
fig. 3 is a schematic diagram illustrating a fault line hierarchy in a fault line searching and locating method according to another embodiment of the present invention;
fig. 4 is a schematic flowchart illustrating step 130 of a fault line searching and locating method according to another embodiment of the present invention;
fig. 5 is a schematic structural diagram of a fault line search positioning system according to an embodiment of the present invention.
Detailed Description
The principles and features of this invention are described below in conjunction with the following drawings, which are set forth by way of illustration only and are not intended to limit the scope of the invention.
Example one
A method 100 for searching and locating a faulty line, as shown in fig. 1, includes the following steps:
and 110, carrying out hierarchical division on the power distribution network to determine the hierarchy of each line in the power distribution network.
And step 120, determining a cutting surface corresponding to each level according to the installation position of the protection device on each line.
And step 130, 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.
The present embodiment aims to provide a new algorithm for quickly searching and positioning a fault line based on wide area information, so as to solve the problem that the existing power distribution network cannot obtain currents at two ends of the line to perform corresponding differential protection judgment and perform a large number of differential judgments at the same time, which may result in a long calculation processing delay.
To achieve the above object, the present embodiment includes: carrying out hierarchical division on the whole power distribution network, and determining a cutting surface corresponding to each hierarchy; and simultaneously, obtaining the line current synchronously output by each protection device according to the wide area information. And searching and judging whether the line has a fault according to a differential protection criterion by using line currents output by the cutting surface and each line protection device, wherein in the differential search judgment process, a dichotomy search mode is adopted to perform longitudinal search and transverse search to determine the fault line. By means of the fault line searching in the mode, the fault searching area can be continuously reduced, the searching calculation amount is greatly reduced, the searching speed is improved, and therefore the quick searching and positioning of the fault line are achieved.
Example two
On the basis of the first embodiment, as shown in fig. 2, step 110 includes:
step 1.1, determining a main trunk line in the power distribution network, and marking the main trunk line as a first-level line.
And step 1.2, determining each branch on a bus connected with the main line, and marking each branch as a second-level line.
And step 1.3, 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.
And 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 current layer levels of each terminal line layer by layer to the level corresponding to the maximum level number, wherein the expanded layer number is the difference value between the maximum layer level and the current layer level.
It should be noted that, because the actual distribution network has many line branches and complex wiring, in order to realize fast and accurate positioning of the fault line, line classification is implemented on the distribution network. When the distribution network is parallel to the main network, the whole network is in tree distribution. Because the states of all components in the power distribution network are difficult to determine in real time and may change at any time, and the classification of the lines is based on the existing network structure, the topological structure of the whole power distribution network is dynamically acquired by means of a reliable state estimation method before fault search is implemented.
After the paired network topology is acquired in real time, the distribution network is classified according to the following principles:
(1) the main trunk line is a first level, each branch line carried on a bus connected with the main trunk line is a second level, and the sub-branch lines branched from each branch line in the same level are the next level lines, and so on. Every branch line that divides, the circuit progression can increase one level, and all branch line head end's current transformer should be concentrated in same search face (cutting plane) in the same one-level circuit, and each grade circuit corresponds a corresponding search face, and along with the increase of circuit progression, the serial number of search face increases progressively in proper order (I, II, III, …), and every search face all intersects with each branch line in this grade circuit.
(2) Since the distribution network is the receiving end, the bus is generally connected with terminal lines (for connecting loads) in addition to the junction lines (lines between the bus and the bus), so that lines intersecting most of the search surface are not only the junction lines but also various terminal lines. Therefore, it is specified that: if the current level is a terminal line, the current level can be expanded to the last level of the current network layer by layer, and in each search plane through which the expanded line passes, the corresponding branch line current is defined to be the same as the current of the terminal line before expansion, wherein the expanded layer number is the difference between the maximum layer number and the current layer number.
For example, as shown in fig. 3, arrows in the drawing represent the flow direction of current, reference numeral 1 represents a power supply, reference numeral 2 represents a trunk line, reference numeral 3 represents a first bus bar, reference numeral 4 represents a second bus bar, reference numeral 5 represents a load, a line between the first bus bar and the second bus bar is a branch line, a line between the first bus bar and the load 5 is a terminal line, a line between the second bus bar and the load 5 is also a terminal line, and dotted arcs in the drawing represent respective cut surfaces. Therefore, the main line 2 in the figure is a first stage, each branch line on the first bus 3 connected to the main line 2 is a second stage, each branch line (terminal line) on the second bus 4 connected to the branch line of the second stage is a third stage, the topological system has three stages in total, and the line connected to the load mounted on the first bus is the second stage, so that the second stage line is expanded, as shown in the figure, each imaginary straight line is an expanded line, the line between the first bus and the imaginary straight line is the second stage, and the imaginary straight line represents the third stage.
For another example, a distribution network has three buses, a trunk line is a first-stage line, a branch on the first bus connected to the trunk line is a second-stage line, part of the second-stage line is connected to a next bus (a second bus), part of the branch is directly connected to a load through a terminal line, branches on the second bus are all connected to a third bus, a branch on the second bus is a third-stage line, a branch on the third bus is connected to a load through a terminal line, the terminal line connected to a branch on the third bus is a fourth-stage line, then the terminal line connected to the branch on the first bus is firstly extended to the third-stage line, and then extended to the fourth-stage line from the third-stage line, at this time, the first-stage line is the trunk line, and the second-stage line is a branch on the first bus (including a branch connecting the first bus and the second bus and a terminal line connecting the first bus and the load), the third-stage circuit comprises a branch circuit on the second bus and a primary expanded circuit expanded by a terminal circuit connected with the first bus and the load, the fourth-stage circuit comprises a terminal circuit connected with the third bus and the load and a secondary expanded circuit expanded by the primary expanded circuit, and the number of expanded layers of the terminal circuit connected with the first bus and the load is 4 minus 2.
The line current of the terminal line connecting the first bus and the load on the cutting surface delivered by the terminal line, the line current of the primary expanded line on the cutting surface delivered by the primary expanded line and the line current of the secondary expanded line on the cutting surface delivered by the secondary expanded line are the same and are defined as the same as the current of the terminal line before expansion.
(3) The terminal line of the last layer only uploads corresponding information for participating in the search of faults of other line layers, the faults occurring on the terminal line are removed by means of original local protection, and the protection of the last layer line does not need to be considered to be matched with other protection, so that any faults occurring on the terminal line can be removed without time limit.
EXAMPLE III
On the basis of the second embodiment, the cutting surface corresponding to each level passes through the tail ends of the protection devices on all lines in the level.
Then, as shown in fig. 4, step 130 comprises:
and step 131, determining a corresponding first hierarchy and a corresponding last hierarchy according to the search area of the power distribution network.
And 132, respectively determining cutting currents on the cutting surfaces corresponding to the first level and the last level according to the line currents synchronously output by the protection devices.
And step 133, calculating a cutting current variation and a cutting current braking amount corresponding to the search area according to the cutting current.
And step 134, judging whether the search area has faults or not according to the cutting current variation, the cutting current braking quantity and a preset differential protection criterion.
Step 135, if yes, determining whether the search area only contains one hierarchy, if yes, executing step 136, if no, dividing the search area into two new search areas by bisection, and executing step 131 on the two new search areas respectively.
And 136, 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, transversely dividing the search area into two new search areas by a dichotomy according to a first line and a last line in the search area, and executing the step 131 on the two new search areas respectively.
It should be noted that, during longitudinal search, the cutting current on each cutting surface is determined according to the line current synchronously output by each protection device; and then, according to the cutting surface and the cutting current, the power distribution network is longitudinally searched through a bisection method, and the level with the fault is determined. And then, carrying out transverse search on the fault hierarchy, and further positioning the fault line, wherein during the transverse search, a first line and a last line of the hierarchy are determined, the hierarchy is divided into two search areas in an bisection mode by adopting a bisection method, the sum of the number of the lines in the two search areas is equal to the number of the lines in the fault search area before the bisection, and then the cutting current on each cutting surface is determined for the two search areas respectively, and fault judgment is carried out.
Specifically, the method of step 130 includes the following steps:
s1: determining a first level and a last level corresponding to a search area of the power distribution network;
s2: according to the line current synchronously output by each protection device, determining a first cutting current on a first cutting surface corresponding to a first layer level and a second cutting current on a second cutting surface corresponding to a last layer level;
s3: calculating a cutting current variable quantity and a cutting current braking quantity corresponding to the search area according to the first cutting current and the second cutting current;
s4: judging whether the search area has a fault according to the cutting current variable quantity, the cutting current braking quantity and a preset differential protection criterion, and if not, finishing the search and positioning of the fault line;
s5: if yes, judging whether the search area only contains one hierarchy, if yes, executing S6, otherwise, dividing the search area into two new search areas by bisection, and executing the step S1 on the two new search areas respectively;
s6: determining a first line and a last line in the search area, and dividing the search area into two new search areas by a bisection method according to the first line and the last line;
s7: determining cutting currents on two cutting surfaces of each new search area according to each line current, and calculating cutting current variation and cutting current braking quantity corresponding to the new search area according to the cutting currents;
s8: judging whether the new search area has a fault or not according to a preset differential protection criterion and the cutting current variation and cutting current braking quantity calculated in the step S7, and if not, ending the fault line search positioning;
s9: if yes, judging whether the new search area only contains one line, if yes, determining that the line is a fault line, and completing fault line search positioning, and if not, executing step S6.
It should be noted that, when determining whether the search area contains only one hierarchy, although the two cut surfaces are located at two hierarchies respectively, each cut surface is located at the head end of the line of the corresponding hierarchy (the protection device on each line is located at the head end of the line, and the cut surface passes through the tail end of the protection device), therefore, the search area between the two cut surfaces contains at least one hierarchy, that is, the search area contains other hierarchies except for the tail hierarchy in the search area.
For example, step 1: and calculating the cutting current of the corresponding search surface. The cutting currents of the search surface I and the search surface II are respectively as follows:and after the current of each branch circuit is subjected to phasor synthesis in a corresponding local unit, the current is uploaded to a protection intelligent center to perform differential protection judgment.
Step 2: and searching vertical partitions. The method comprises the steps that a first-level line set and a last-level line set of a searched area respectively correspond to a search surface (cutting surface), firstly, the area between the first search surface and the last search surface is subjected to one-time longitudinal partition search, the variation and the braking quantity of a cutting current in each area are calculated, whether the variation and the braking quantity meet a fault criterion (differential protection criterion) or not is judged, if the variation and the braking quantity do not meet the criterion, a fault is considered to be out of the range governed by a protection intelligent center, and the area does not need to be subjected to next fault search; if the criterion is met, the partition searching is continued, the original area is changed into two new areas, and the total number of the line levels in each new area is reduced by about half. For the two new areas, the searching is carried out according to the steps, and the fault necessarily exists in one area. And repeating the process until the line level number in the area becomes 1, wherein the longitudinal search is terminated, and the fault branch is necessarily positioned on the line level sandwiched by two search surfaces in the last longitudinal search.
The set of vertical partitions represents: if i is the first line level number in the area to be searched before partitioning, and n is the line level number in the area, two newly generated areas after one longitudinal search partitioning are set as
And step 3: and (5) horizontal searching. After a fault branch is positioned on a line level sandwiched by two adjacent search surfaces in the longitudinal fault search, the line level is determined as a transverse area to be searched, transverse partition search is carried out on the area, and the search process is the same as the longitudinal search. And when the number of the lines in the area to be searched is equal to 1, the fault line is successfully positioned, and the fault line can be positioned after the transverse partition search is finished.
The set of horizontal partitions represents: let j be the first branch number before partitioning the horizontal to-be-searched area, and m be the number of branch lines in the area, then two newly-generated areas after one horizontal search partitioning are
The present embodiment aims to provide a new algorithm for quickly searching and positioning a fault line based on wide area information, so as to solve the problem that the existing power distribution network cannot obtain currents at two ends of the line to perform corresponding differential protection judgment and perform a large number of differential judgments at the same time, which may result in a long calculation processing delay. To achieve the above object, the present embodiment includes: and carrying out hierarchical division on the whole power distribution network, and determining the cutting current components of different search surfaces. And calculating the cutting current variable quantity and the braking quantity of the corresponding search surface by using the determined cutting current so as to form a criterion of differential protection, and judging whether a fault occurs in the region by using the criterion. And in the differential search judgment process of the whole area, a search mode of a dichotomy is adopted to carry out longitudinal search and transverse search so as to determine a fault line. By means of the fault line searching in the mode, the fault searching area can be continuously reduced, the searching calculation amount is greatly reduced, the searching speed is improved, and therefore the quick searching and positioning of the fault line are achieved.
Example four
On the basis of the third embodiment, the change amount of the cut currentBraking amount of cutting currentThe preset differential protection criterion is expressed as:wherein,expressed as the corresponding cutting current of the first level,the current is expressed as the corresponding cutting current of the last level, and k is expressed as the braking coefficient.
Step 134 includes: and judging whether a preset differential protection criterion is established or not according to the cutting current variable quantity, the cutting current braking quantity and the braking coefficient, and if so, judging that the search area has a fault.
In addition, k represents a braking coefficient, and is usually 0.3 to 0.7.
EXAMPLE five
On the basis of the third or fourth embodiment, the cutting current is expressed 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.
EXAMPLE six
A faulty line search location system 200, as shown in fig. 5, comprises:
and the hierarchy dividing module is used for carrying out hierarchy dividing on the power distribution network and determining the hierarchy of each line in the power distribution network.
And 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 and positioning.
EXAMPLE seven
On the basis of the sixth embodiment, the hierarchical dividing 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 a 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 level number layer by layer according to the current level number of each terminal line, wherein the expanded layer number is the difference value between the maximum layer number and the current layer number.
Example eight
On the basis of the seventh embodiment, the cutting surface corresponding to each level passes through the ends of the protection devices on all lines in the level.
The positioning module is specifically configured to: determining a first level and a last level corresponding to a search area of the power distribution network; respectively determining cutting currents on cutting surfaces corresponding to a first level and a last level according to line currents synchronously output by each protection device; according to the cutting current, calculating the cutting current variation and the 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 the line as a fault line to complete fault line search positioning, otherwise, horizontally dividing the search area into two new search areas by a dichotomy 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 first level and a last level corresponding to the two new search areas.
Example nine
On the basis of the eighth embodiment, the change amount of the cut currentBraking amount of cutting currentThe preset differential protection criterion is expressed as:wherein,expressed as the corresponding cutting current of the first level,the current is expressed as the corresponding cutting current of the last level, and k is expressed as the braking coefficient.
The positioning module specifically includes, when it is determined whether the search area has a fault: and judging whether a preset differential protection criterion is established or not according to the cutting current variable quantity, the cutting current braking quantity and the braking coefficient, and if so, judging that the search area has a fault.
In addition, k represents a braking coefficient, and is usually 0.3 to 0.7.
Example ten
On the basis of the eighth embodiment or the ninth embodiment, the cutting current is expressed 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.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.
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.
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