CN114113948B - Power distribution network fault monitoring method - Google Patents
Power distribution network fault monitoring method Download PDFInfo
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Abstract
The invention discloses a power distribution network fault monitoring method, which comprises the following steps: monitoring traveling wave signals by taking the head end and the tail end of the power distribution network and the tail end of each branch as monitoring points respectively; constructing a monitoring tree for each monitoring point; responding to the occurrence of a power distribution network fault, and obtaining first distances from each monitoring point to the fault point respectively; obtaining a first fault branch set of a fault point on a monitoring tree of each monitoring point for each monitoring point; screening and recombining each first fault branch set to obtain a second fault branch set; adding distances from fault points in elements with the same suspected branches in the second fault branch set to the first node to obtain a plurality of judgment distances; and selecting the maximum value of the judging distances as a main judging distance, and the rest judging distances as secondary judging distances; obtaining a fault distance according to the main judgment distance and the secondary judgment distance; and further obtaining the specific position of the fault point in the power distribution network. The invention improves the fault monitoring and positioning efficiency and precision.
Description
Technical Field
The invention relates to the field of power distribution networks, in particular to a power distribution network fault monitoring method.
Background
The distribution network refers to a power network that receives electric energy from a power transmission network or a regional power plant, and distributes the electric energy locally or step by step according to voltage through a distribution facility. The system consists of overhead lines, cables, towers, distribution transformers, isolating switches, reactive compensators, a plurality of auxiliary facilities and the like, and plays a role in distributing electric energy in a power network. Distribution networks play a vital role in power systems. Once the power distribution network fails, huge losses are caused if the power distribution network is not repaired in time. Monitoring and locating faults in the distribution network is therefore an indispensable technology in the field of distribution networks.
The accurate positioning of the faults of the power distribution network mainly comprises 4 classifications of an impedance method, a steady-state fault accurate positioning method of non-impedance analysis, a transient fault accurate positioning method of traveling wave method and non-traveling wave analysis. The traveling wave method is the most commonly used method for monitoring and positioning faults of the power distribution network because of simplicity and effectiveness. In a multi-terminal power distribution network, the time difference of arrival of the traveling wave at different measuring terminals is used for accurate positioning, namely double-terminal positioning. The double-end method is applied to multi-end power distribution network fault monitoring and positioning, two different ends are required to be selected as traveling wave monitoring ends to calculate whether faults occur on a line between the two selected ends, and the two ends are continuously selected in a traversing mode until the faults are positioned. The method is not only low in efficiency, but also only adopts data of two endpoints when the fault is positioned, so that the data volume is too small, and the fault positioning precision is poor.
Disclosure of Invention
In view of the above-mentioned part of the drawbacks of the prior art, the present invention provides a method for monitoring faults of a power distribution network, which aims to improve the efficiency and the accuracy of fault monitoring and positioning of the power distribution network.
In order to achieve the above object, the present invention provides a power distribution network fault monitoring method, which includes:
monitoring traveling wave signals by taking the head end and the tail end of the power distribution network and the tail end of each branch as monitoring points respectively;
for each of the monitoring points: taking the monitoring points as root nodes, taking nodes of the power distribution network as branch nodes, taking the rest monitoring points as leaf nodes, taking actual lines of the power distribution network as branches connected with all the nodes, and constructing a monitoring tree;
responding to the occurrence of a power distribution network fault, collecting fault traveling wave signals received by each monitoring point, and obtaining first distances from each monitoring point to the fault point according to the fault traveling wave signals;
for each of the monitoring points: substituting the first distance corresponding to the monitoring point into a monitoring tree of the monitoring point to obtain a first fault branch set of the fault point on the monitoring tree of the monitoring point; each element in the first fault branch set comprises a suspected fault branch and a distance from the fault point to nodes at two ends of the suspected fault branch;
screening and reorganizing each first fault branch set to obtain a second fault branch set; at least one element in each first fault branch set is recombined into the second fault branch set, and the suspected fault branches of each element in the second fault branch set comprise the same node, and the node is called a first node;
adding distances from the fault point to the first node in the elements with the same suspected branches in the second fault branch set to obtain a plurality of judgment distances; and selecting the maximum value of the judging distances as a main judging distance, and the rest judging distances as secondary judging distances;
according toObtaining a fault distance; wherein S is the fault distance, L max For the main judgment distance L i For the secondary judgment distance, n is the number of the secondary judgment distances, i is the number of the secondary judgment distances and i is more than 0, p is the number of the distances from the fault point corresponding to the primary judgment distance to the first node, q i The number of the distances from the fault point to the first node corresponding to the secondary judgment distance is the number of the distances from the fault point to the first node;
and obtaining the specific position of the fault point in the power distribution network according to the suspected fault branch and the fault distance corresponding to the main judgment distance.
Optionally, the obtaining, according to the suspected fault branch and the fault distance corresponding to the main judgment distance, a specific position of the fault point on the power distribution network includes:
determining the suspected fault branch corresponding to the main judgment distance as a fault existence branch;
and determining the position of the fault existing branch extending the fault distance from the first node to the fault existing branch center as the specific position of the fault point in the power distribution network.
Optionally, the taking the actual line of the power distribution network as a branch for connecting each node includes:
and (3) reducing the actual line between the monitoring point in the power distribution network and the node of the power distribution network according to a preset proportion, and taking the actual line as a branch for connecting each node in a monitoring tree.
Optionally, collecting the received fault travelling wave signals of each monitoring point, and before obtaining the first distances from each monitoring point to the fault point according to the fault travelling wave signals, the method further includes:
and responding to the occurrence of the fault of the power distribution network, and injecting the initial traveling wave signal from each monitoring point, wherein the initial traveling wave signal is an incident wave signal of the fault traveling wave signal.
Optionally, the method further comprises:
when a power distribution network has no faults, a first traveling wave signal is injected into the head end of the power distribution network, and a first time point is recorded;
collecting the time when the monitoring points except the head end receive the first line wave signal, and recording the time as a plurality of second time points;
and obtaining the propagation speed of the traveling wave in the power distribution network according to the first time point, the plurality of second time points and the actual line distance from the head end to other monitoring points.
Optionally, the obtaining the propagation speed of the traveling wave in the power distribution network according to the first time point, the plurality of second time points, and the actual line distances from the head end to the other monitoring points includes:
according toAcquiring the propagation speed of a traveling wave in the power distribution network; wherein v is the propagation speed of the traveling wave in the power distribution network, T 1 For the first time point, T b For the second time point, b is the number of the second time point and b is more than 0, a is the number of the second time point, L b And the actual line distance from the monitoring point corresponding to the second time to the head end is obtained.
Optionally, the method further comprises:
and installing traveling wave signal measuring and acquiring devices for monitoring traveling wave signals at the monitoring points.
The invention has the beneficial effects that: 1. the invention takes the head end, the tail end and the tail end of each branch of the power distribution network as the monitoringMeasuring points, monitoring traveling wave signals; for each monitoring point: taking the monitoring points as root nodes, taking nodes of the power distribution network as branch nodes, taking the rest monitoring points as leaf nodes, taking actual lines of the power distribution network as branches connected with all the nodes, and constructing a monitoring tree; responding to the occurrence of a power distribution network fault, collecting fault traveling wave signals received by all monitoring points, and obtaining first distances from all the monitoring points to the fault points respectively according to the fault traveling wave signals; for each monitoring point: substituting the first distance corresponding to the monitoring point into a monitoring tree of the monitoring point to obtain a first fault branch set of the fault point on the monitoring tree of the monitoring point; each element in the first fault branch set comprises a suspected fault branch and a distance from a fault point to nodes at two ends of the suspected fault branch. According to the invention, the monitoring tree is built through each monitoring point, the position of the fault point in the power distribution network can be obtained by substituting the first distance between the fault point and each monitoring point into the monitoring tree, and the monitoring tree can be always used after the power distribution network is built. Compared with the prior art, the method and the device for calculating the fault of the power distribution network can effectively improve the fault monitoring and positioning efficiency of the power distribution network. In addition, the monitoring tree can intuitively show the position of the fault point. 2. The method comprises the steps of screening and recombining each first fault branch set to obtain a second fault branch set; adding distances from fault points in elements with the same suspected branches in the second fault branch set to the first node to obtain a plurality of judgment distances; and selecting the maximum value of the judging distances as a main judging distance, and the rest judging distances as secondary judging distances; according toObtaining a fault distance; and obtaining the specific position of the fault point in the power distribution network according to the suspected fault branch and the fault distance corresponding to the main judgment distance. Compared with the prior art which only adopts two end points for calculation, the fault point position obtained by the method can not cause great influence due to the deviation of one element, thereby ensuring the obtained fault point positionMore accurate. 3. According to the invention, after actual lines between monitoring points in the power distribution network and nodes of the power distribution network are reduced according to a preset proportion, the actual lines are used as branches for connecting all nodes in a monitoring tree. The invention reduces the actual line according to the preset proportion and then is used as the branch for connecting each node in the monitoring tree, thereby ensuring that the monitoring tree reflects the position of the fault point to be more visual and obvious. 4. When the power distribution network has no fault, a first traveling wave signal is injected into the head end of the power distribution network, and a first time point is recorded; collecting the time when other monitoring points except the head end receive the first line wave signal, and recording the time as a plurality of second time points; and obtaining the propagation speed of the traveling wave in the power distribution network according to the first time point, the plurality of second time points and the actual line distance from the head end to other monitoring points. According to the invention, the propagation speed of the traveling wave in the power distribution network is measured by the self, so that inaccuracy caused by directly adopting the light speed is avoided, and the accuracy of obtaining the propagation speed is ensured by taking the average value of the propagation speeds obtained at different monitoring ends. In summary, the invention constructs the monitoring tree, substitutes each first distance into the monitoring tree to obtain the first fault branch set, further obtains the second fault branch set, calculates the elements in the second fault branch set, and thus obtains the specific position of the fault point in the power distribution network.
Drawings
Fig. 1 is a schematic flow chart of a power distribution network fault monitoring method according to an embodiment of the present invention;
fig. 2 is a structural topology of a first power distribution network according to a first embodiment of the present invention;
fig. 3 is a schematic structural diagram of a monitoring tree using a head end a as a root node according to a first embodiment of the present invention;
fig. 4 is a schematic structural diagram of a monitoring tree with a branch end B as a root node according to a first embodiment of the present invention;
fig. 5 is a schematic structural diagram of a monitoring tree with a branch end C as a root node according to a first embodiment of the present invention;
fig. 6 is a schematic structural diagram of a monitoring tree with a branch end D as a root node according to a first embodiment of the present invention;
fig. 7 is a schematic structural diagram of a monitoring tree with a branch end E as a root node according to a first embodiment of the present invention;
fig. 8 is a schematic structural diagram of a monitoring tree with a terminal F as a root node according to a first embodiment of the present invention.
Detailed Description
The invention discloses a power distribution network fault monitoring method, and a person skilled in the art can refer to the content of the power distribution network fault monitoring method and properly improve technical details. It is expressly noted that all such similar substitutions and modifications will be apparent to those skilled in the art, and are deemed to be included in the present invention. While the methods and applications of this invention have been described in terms of preferred embodiments, it will be apparent to those skilled in the relevant art that variations and modifications can be made in the methods and applications described herein, and in the practice and application of the techniques of this invention, without departing from the spirit or scope of the invention.
The research of the applicant shows that: in a multi-terminal power distribution network, the time difference of arrival of the traveling wave at different measuring terminals is used for accurate positioning, namely double-terminal positioning. The double-end method is applied to multi-end power distribution network fault monitoring and positioning, two different ends are required to be selected as traveling wave monitoring ends to calculate whether faults occur on a line between the two selected ends, and the two ends are continuously selected in a traversing mode until the faults are positioned. The application of the double-end method in the multi-end power distribution network has low efficiency because each endpoint needs to be traversed continuously; and when the fault is located, only data at two ends of the fault line are adopted, so that the data at the two ends are slightly inaccurate, and the inaccurate influence is amplified to a locating result.
Accordingly, an embodiment of the present invention discloses a method for monitoring faults of a power distribution network, as shown in fig. 1, the method includes:
step S101: and monitoring the traveling wave signals by taking the head end and the tail end of the power distribution network and the tail end of each branch as monitoring points.
Optionally, the method further comprises:
and a traveling wave signal measuring device for monitoring the traveling wave signal is arranged at each monitoring point.
A traveling wave (traveling wave) refers to a transmission state of a plane wave on a transmission line, in which the amplitude varies exponentially along the propagation direction and the phase varies linearly along the transmission line.
Step S102: for each monitoring point: and taking the monitoring points as root nodes, taking nodes of the power distribution network as branch nodes, taking the rest monitoring points as leaf nodes, and taking actual lines of the power distribution network as branches connected with all the nodes to construct a monitoring tree.
It should be noted that the nodes are the intersections of the branches of the distribution network, and the nodes are the nodes of the tree, and the nodes have the same pronunciation but distinct meaning.
Optionally, taking an actual line of the power distribution network as a branch for connecting each node, including:
and (3) reducing the actual line between the monitoring point in the power distribution network and the node of the power distribution network according to a preset proportion, and taking the actual line as a branch for connecting each node in the monitoring tree.
It should be noted that, by constructing the monitoring tree, the embodiment of the invention can more intuitively and rapidly identify the fault point.
Step S103: and responding to the occurrence of the faults of the power distribution network, collecting fault traveling wave signals received by all monitoring points, and obtaining the first distances from all the monitoring points to the fault points respectively according to the fault traveling wave signals. The first distance is the distance from the monitoring point to the fault point.
Optionally, before the fault traveling wave signals are collected and the first distances from the monitoring points to the fault points are obtained according to the fault traveling wave signals, the method further includes:
and in response to the occurrence of the fault of the power distribution network, injecting an initial traveling wave signal from each monitoring point, wherein the initial traveling wave signal is an incident wave of the fault traveling wave signal.
The invention can be measured by single-ended methods, i.e. by measuring the round trip time of the fault travelling wave at the fault point and at the measuring end.
In particular, for exampleThe time point of the initial traveling wave signal injected by the measuring end is 27 mu s, the time point of the fault traveling wave signal received is 28 mu s, the traveling wave propagation speed is 300000km/s, and the fault distance is 3 multiplied by 10 8 ×(28-27)×10 -6 ＝300m。
In the embodiment of the invention, the first distances from the monitoring points to the fault points respectively are not limited to be obtained by adopting a single-end method, and the first distances can be obtained by adopting other methods, so long as the concept of the invention is not deviated, the protection scope of the invention can be considered.
Step S104: for each monitoring point: substituting the first distance corresponding to the monitoring point into the monitoring tree of the monitoring point to obtain a first fault branch set of the fault point on the monitoring tree of the monitoring point.
Each element in the first fault branch set comprises a suspected fault branch and a distance from a fault point to nodes at two ends of the suspected fault branch.
The suspected fault branch is a branch where the fault point may exist, e.g. the monitoring point O is calculated 1 A first distance to the fault point is 300m, branch O 1 O 2 And branch O 1 O 3 500m each, branch O 1 O 2 And branch O 1 O 3 Is a suspected faulty branch.
Specifically, elements in the first set of failed branches may be represented as [ O ] 1 O 2 ,300m,200m]，O 1 O 2 For indicating suspected faulty branches, O 1 And O 2 Is the two end nodes of two suspected fault branches, 300m is the fault point to O 1 200m is the distance from the fault point to O 2 Is a distance of (3).
Step S105: screening and reorganizing each first fault branch set to obtain a second fault branch set; at least one element in each first fault branch set is recombined into a second fault branch set, and suspected fault branches of each element in the second fault branch set comprise the same node, and the node is called a first node.
Specifically, if the first faulty branch sets are set 1, set 2, and set 3, set 1, set 2, and set 3 are respectively:
{[O 1 O 2 ,300m,200m],[O 3 O 4 ,75m,120m],[O 3 O 5 ,75m,220m]}
{[O 6 O 7 ,100m,70m],[O 8 O 9 ,65m,220m],[O 1 O 3 ,35m,120m]}
{[O 10 O 11 ,100m,70m],[O 10 O 12 ,65m,220m],[O 1 O 4 ,295m,220m]}
from the three sets, all nodes O with the same node are selected 1 Recombination is carried out, i.e. of element [ O ] 1 O 2 ,300m,200m]，[O 1 O 3 ,35m,120m]And [ O ] 1 O 4 ,295m,220m]Obtaining a second set of faulty branches: { [ O ] 1 O 2 ,300m,200m],[O 1 O 3 ,35m,120m],[O 1 O 4 ,295m,220m]}。
In the above set, there are typically no other nodes between the nodes at both ends of all branches, but there are exceptions as follows:
such as O 1 For the first node, leave O in the faulty branch 1 The longest node distance is 300m, where O 1 No other nodes are present between the node, but there is a first set of faulty branches, e.g. { [ O 2 O 3 ,50m,200m],[O 3 O 4 ,75m,120m],[O 3 O 5 ,75m,220m]No junction O 1 Elemental, also having O 1 O 2 200+50 if the length of (2) is 200m<300, it can be considered that O 2 O 3 The first faulty branch is aggregated into { [ O ] 1 O 3 ,250m,200m],[O 3 O 4 ,75m,120m],[O 3 O 5 ,75m,220m]}. It should be noted that if the first faulty branch set includes the first node, the method may be simplified.
Step S106: adding distances from fault points in elements with the same suspected branches in the second fault branch set to the first node to obtain a plurality of judgment distances; and selecting the maximum value of the judging distances as a main judging distance, and the rest judging distances as secondary judging distances.
For example, the second set of faulty branches is:
{[O 1 O 2 ,300m,200m],[O 1 O 3 ,35m,120m],[O 1 O 4 ,15m,220m],[O 1 O 3 ,38m,118m],,[O 1 O 2 ,298m,202m],}
to be aware of O 1 For the first node, the primary judgment distance is 300+298=598m, and the secondary judgment distances are 35+38=73m and 15m, respectively.
Step S107: according toObtaining a fault distance; wherein S is the fault distance, L max Mainly determine distance L i For the secondary judgment distance, n is the number of the secondary judgment distances, i is the number of the secondary judgment distances and i is more than 0, p is the number of the distances from the fault point corresponding to the primary judgment distance to the first node, q i The number of the distances from the fault point corresponding to the secondary judgment distance to the first node is determined.
The fault distance is calculated comprehensively for a plurality of data, and the method has the characteristics of small error and high accuracy.
In particular, it is necessary to prevent errors, the heating error prevention constants z, z are greater than 0, and the fault distance has a value in the range of [ S-z, s+z ].
Step S108: and obtaining the specific position of the fault point in the power distribution network according to the suspected fault branch and the fault distance corresponding to the main judgment distance.
Optionally, obtaining the specific position of the fault point in the power distribution network according to the suspected fault branch and the fault distance corresponding to the main judgment distance includes:
determining a suspected fault branch corresponding to the main judgment distance as a fault existence branch;
and confirming the position of the fault existing branch extending the fault distance from the first node to the fault existing branch center as the specific position of the fault point in the power distribution network.
Optionally, the method further comprises:
when the power distribution network has no fault, a first traveling wave signal is injected into the head end of the power distribution network, and a first time point is recorded;
collecting the time when other monitoring points except the head end receive the first line wave signal, and recording the time as a plurality of second time points;
and obtaining the propagation speed of the traveling wave in the power distribution network according to the first time point, the plurality of second time points and the actual line distance from the head end to other monitoring points.
Further, according to the first time point, the plurality of second time points and the actual line distance from the head end to other monitoring points, the method for obtaining the propagation speed of the traveling wave in the power distribution network comprises the following steps:
according toAcquiring the propagation speed of a traveling wave in a power distribution network; wherein v is the propagation speed of the traveling wave in the power distribution network, T 1 For the first time point, T b For the second time point, b is the number of the second time point and b is more than 0, a is the number of the second time point, L b And the actual line distance from the monitoring point corresponding to the second time to the head end is obtained.
The following description is made in connection with a first embodiment, which is as follows:
as shown in fig. 2-8, fig. 2 is a first embodiment, in fig. 2, a is a head end of a power distribution network, F is a tail end of the power distribution network, B, C, D and E are tail ends of branches, T1, T2, T3 and T4 are nodes of the power distribution network, and each branch length is as follows: AT1 was 300m, T1T2 was 300m, T2T3 was 300m, T3F was 600m, T1 was 600m, T3T4 was 300m, T4 was 300m.
If the first distance from the fault point to the monitoring point a is 605m, as shown in fig. 3, H represents the fault point in fig. 3, H may exist in three branches of BT1, CT2 and T2T3, and the first fault branch set of the monitoring point a is { [ BT1, 305m,295m ], [ CT2, 595m,5m ], [ T2T3,5m,295m ] }.
The first distance from the fault point to the monitoring point B is 895m, as shown in fig. 4, where H represents the fault point, where H may exist in two branches AT1 and T1T2, and the first set of fault branches AT the monitoring point B is { [ AT1,5m,295m ], [ T1T2, 295m,5m ].
The first distance from the fault point to the monitoring point C is 603m, as shown in fig. 5, where H represents the fault point in fig. 5, where H may exist in two branches of T1T2 and T2T3, and the first fault branch set of the monitoring point C is { [ T1T2, 293 m,3m ], [ T2T3,3m, 293 m ] }.
The first distance from the fault point to the monitoring point D is 898m, as shown in fig. 6, where H represents the fault point, where H may exist in two branches of T2T3 and T3F, and the first set of fault branches of the monitoring point D is { [ T2T3,2m,298m ], [ T3F,298m,2m ] }.
The first distance from the fault point to the monitoring point E is 903m, as shown in fig. 7, where H represents the fault point, where H may exist in two branches of T1T2 and CT2, and the first fault branch set of the monitoring point E is { [ T1T2, 294 m,3m ], [ CT2, 597m,3m ] }.
The first distance from the fault point to the monitoring point F is 604m, as shown in fig. 3, where H represents the fault point, and H may exist in three branches T1T2, CT2, DT4, and ET4, and the first fault branch set of the monitoring point F is { [ T1T2, 298m, 4m ], [ CT2, 596m,4m ], [ DT4, 298m, 4m ], [ ET4, 298m, 4m ] }.
According to the first specific embodiment, each first faulty branch set may be determined to have an element including node T2, where T2 is determined to be the first node, and then there is a second faulty branch set of { [ CT2, 595m,5m ], [ T2T3,5m,295m ], [ T1T2, 295m,5m ], [ T1T2, 292 m,3m, 292 m ], [ T2T3,2m,298m ], [ T1T2, 292 m,3m ], [ CT2, 597m,3m ], [ T1T2, 256 m,4m ], [ CT2, 596m,4m ] }.
The distances from the fault point to the first node in the fault branch T1T2 are added, i.e. 5+3+3+4=15m. The distances of the fault points of the faulty branch T2T3 to the first node are added, i.e. 5+3+2=10m. The distances of the fault points of the fault branch CT2 to the first node are added, i.e. 5+3+4=12m.
15m,10m and 12m are obtained as judging distances, 15m is a main judging distance, and the rest judging distances are secondary judging distances.
According toThe failure distance S of the first embodiment was found to be 0.57m.
The fault point of the first embodiment is located on branch T1T2 and is a distance of 0.57m from T2.
In a specific application, errors are often prevented, and 0.5m is taken as an error preventing parameter, so that the distance between the fault point and T2 is in [0.07m,1.07m ].
According to the embodiment of the invention, the traveling wave signals are monitored by taking the head end, the tail end and the tail end of each branch of the power distribution network as monitoring points respectively; for each monitoring point: taking the monitoring points as root nodes, taking nodes of the power distribution network as branch nodes, taking the rest monitoring points as leaf nodes, taking actual lines of the power distribution network as branches connected with all the nodes, and constructing a monitoring tree; responding to the occurrence of a power distribution network fault, collecting fault traveling wave signals received by all monitoring points, and obtaining first distances from all the monitoring points to the fault points respectively according to the fault traveling wave signals; for each monitoring point: substituting the first distance corresponding to the monitoring point into a monitoring tree of the monitoring point to obtain a first fault branch set of the fault point on the monitoring tree of the monitoring point; each element in the first fault branch set comprises a suspected fault branch and a distance from a fault point to nodes at two ends of the suspected fault branch. According to the embodiment of the invention, the monitoring tree is built through each monitoring point, the first distance between the fault point and each monitoring point is substituted into the monitoring tree to obtain the position of the fault point on the power distribution network, and the monitoring tree can be always used after the power distribution network is built. Compared with the prior art, the method and the device for calculating the fault of the power distribution network traverse each endpoint, the fault monitoring and positioning efficiency of the power distribution network can be effectively improved. In addition, the monitoring tree of the embodiment of the invention can intuitively show the position of the fault point. The embodiment of the invention obtains the first fault branch sets by screening and recombining the first fault branch setsTwo fault branch sets; adding distances from fault points in elements with the same suspected branches in the second fault branch set to the first node to obtain a plurality of judgment distances; and selecting the maximum value of the judging distances as a main judging distance, and the rest judging distances as secondary judging distances; according toObtaining a fault distance; and obtaining the specific position of the fault point in the power distribution network according to the suspected fault branch and the fault distance corresponding to the main judgment distance. Compared with the prior art that only two end points are used for calculation, the fault point position obtained by the embodiment of the invention cannot be greatly influenced by the deviation of one element, so that the obtained fault point position is more accurate. According to the embodiment of the invention, after actual lines between monitoring points in the power distribution network and nodes of the power distribution network are reduced according to the preset proportion, the actual lines are used as branches for connecting all nodes in a monitoring tree. According to the embodiment of the invention, the actual line is reduced according to the preset proportion and then used as a branch for connecting each node in the monitoring tree, so that the monitoring tree can be ensured to embody the position of the fault point to be more visual and obvious. When the power distribution network has no faults, the first traveling wave signal is injected into the head end of the power distribution network, and a first time point is recorded; collecting the time when other monitoring points except the head end receive the first line wave signal, and recording the time as a plurality of second time points; and obtaining the propagation speed of the traveling wave in the power distribution network according to the first time point, the plurality of second time points and the actual line distance from the head end to other monitoring points. According to the embodiment of the invention, the propagation speed of the traveling wave in the power distribution network is measured by the device, inaccuracy caused by directly adopting the light speed is avoided, and the accuracy of obtaining the propagation speed is ensured by taking the average value of the propagation speeds obtained by different monitoring ends. In summary, the embodiment of the invention obtains the first fault branch set by constructing the monitoring tree, substituting each first distance into the monitoring tree, further obtains the second fault branch set, and calculates the elements in the second fault branch set, thereby obtaining the fault pointIn a specific position of the power distribution network, the embodiment of the invention can simultaneously improve the power distribution network fault monitoring and positioning efficiency and the fault positioning precision.
It is noted that relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises an element.
In this specification, each embodiment is described in a related manner, and identical and similar parts of each embodiment are all referred to each other, and each embodiment mainly describes differences from other embodiments. In particular, for system embodiments, since they are substantially similar to method embodiments, the description is relatively simple, as relevant to see a section of the description of method embodiments.
The foregoing is merely illustrative of the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention are included in the protection scope of the present invention.
Claims (7)
1. A method for monitoring faults in a power distribution network, the method comprising:
monitoring traveling wave signals by taking the head end and the tail end of the power distribution network and the tail end of each branch as monitoring points respectively;
for each of the monitoring points: taking the monitoring points as root nodes, taking nodes of the power distribution network as branch nodes, taking the rest monitoring points as leaf nodes, taking actual lines of the power distribution network as branches connected with all the nodes, and constructing a monitoring tree;
responding to the occurrence of a power distribution network fault, collecting fault traveling wave signals received by each monitoring point, and obtaining first distances from each monitoring point to the fault point according to the fault traveling wave signals;
for each of the monitoring points: substituting the first distance corresponding to the monitoring point into a monitoring tree of the monitoring point to obtain a first fault branch set of the fault point on the monitoring tree of the monitoring point; each element in the first fault branch set comprises a suspected fault branch and a distance from the fault point to nodes at two ends of the suspected fault branch;
screening and reorganizing each first fault branch set to obtain a second fault branch set; at least one element in each first fault branch set is recombined into the second fault branch set, and the suspected fault branches of each element in the second fault branch set comprise the same node, and the node is called a first node;
adding distances from the fault point to the first node in the elements with the same suspected branches in the second fault branch set to obtain a plurality of judgment distances; and selecting the maximum value of the judging distances as a main judging distance, and the rest judging distances as secondary judging distances;
according toObtaining a fault distance; wherein S is the fault distance, L max For the main judgment distance L i For the secondary judgment distance, n is the number of the secondary judgment distances, i is the number of the secondary judgment distances and i is more than 0, p is the number of the distances from the fault point corresponding to the primary judgment distance to the first node, q i The number of the distances from the fault point to the first node corresponding to the secondary judgment distance is the number of the distances from the fault point to the first node;
and obtaining the specific position of the fault point in the power distribution network according to the suspected fault branch and the fault distance corresponding to the main judgment distance.
2. The method according to claim 1, wherein the obtaining the specific location of the fault point on the power distribution network according to the suspected fault branch and the fault distance corresponding to the main judgment distance includes:
determining the suspected fault branch corresponding to the main judgment distance as a fault existence branch;
and determining the position of the fault existing branch extending the fault distance from the first node to the fault existing branch center as the specific position of the fault point in the power distribution network.
3. The method according to claim 1, wherein the branching of the actual line of the power distribution network to connect the nodes comprises:
and (3) reducing the actual line between the monitoring point in the power distribution network and the node of the power distribution network according to a preset proportion, and taking the actual line as a branch for connecting each node in a monitoring tree.
4. The method of claim 1, wherein the step of collecting received fault traveling wave signals for each of the monitoring points, and wherein before obtaining a first distance from each of the monitoring points to a fault point based on the fault traveling wave signals, the method further comprises:
and responding to the occurrence of the fault of the power distribution network, and injecting initial traveling wave signals from each monitoring point, wherein the initial traveling wave signals are incident waves of the fault traveling wave signals.
5. The method according to claim 1, wherein the method further comprises:
when a power distribution network has no faults, a first traveling wave signal is injected into the head end of the power distribution network, and a first time point is recorded;
collecting the time when the monitoring points except the head end receive the first line wave signal, and recording the time as a plurality of second time points;
and obtaining the propagation speed of the traveling wave in the power distribution network according to the first time point, the plurality of second time points and the actual line distance from the head end to other monitoring points.
6. The method according to claim 5, wherein the obtaining the traveling wave propagation speed in the power distribution network according to the first time point, the second time points and the actual line distances from the head end to the other monitoring points includes:
according toAcquiring the propagation speed of a traveling wave in the power distribution network; wherein v is the propagation speed of the traveling wave in the power distribution network, T 1 For the first time point, T b For the second time point, b is the number of the second time point and b is more than 0, a is the number of the second time point, L b And the actual line distance from the monitoring point corresponding to the second time to the head end is obtained.
7. The method according to claim 1, wherein the method further comprises:
and installing traveling wave signal measuring and acquiring devices for monitoring traveling wave signals at the monitoring points.
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