CN114113948A - 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: respectively taking the head end and the tail end of the power distribution network and the tail ends of all branches as monitoring points to monitor the traveling wave signals; constructing a monitoring tree for each monitoring point; responding to the occurrence of the power distribution network fault, and obtaining first distances from each monitoring point to the fault point; for each monitoring point, obtaining a first fault branch set of the fault point on a monitoring tree of the monitoring point; screening and recombining each first fault branch set to obtain a second fault branch set; adding distances from fault points 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; selecting the maximum value in the judgment distances as a main judgment distance, and taking the rest judgment distances as secondary judgment distances; obtaining a fault distance according to the primary judgment distance and the secondary judgment distance; and further acquiring the specific position of the fault point in the power distribution network. The invention improves the efficiency and the precision of fault monitoring and positioning.
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 is an electric power network which receives electric energy from a transmission network or a regional power plant and distributes the electric energy to various users on site through distribution facilities or step by step according to voltage. The power distribution network consists of overhead lines, cables, towers, distribution transformers, isolating switches, reactive power compensators, accessory facilities and the like, and plays a role in distributing electric energy in a power network. Power distribution networks play a vital role in power systems. Once the power distribution network fails, huge loss can be caused if the power distribution network is not repaired in time. Therefore, monitoring and positioning of power distribution network faults are indispensable technologies in the field of power distribution networks.
The accurate positioning of the power distribution network faults mainly comprises 4 categories, namely an impedance method, a steady-state fault accurate positioning method of non-impedance analysis, and a transient fault accurate positioning method of traveling wave analysis and non-traveling wave analysis. The traveling wave method is the most common method for monitoring and locating the faults of the power distribution network because the traveling wave method is simple and effective. In a multi-terminal power distribution network, the time difference of traveling waves arriving at different measuring terminals is often accurately positioned, namely, the positioning by a double-terminal method. The double-end method is applied to fault monitoring and positioning of a multi-end power distribution network, two different ends are required to be selected as traveling wave monitoring ends to calculate whether a fault occurs on a line between the two selected ends, and the two ends are continuously selected in a traversal mode until the fault is positioned. The method is not only low in efficiency, but also generally only adopts data of two end points 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 some of the above drawbacks in the prior art, the present invention provides a method for monitoring a fault of a power distribution network, which aims to improve the efficiency and accuracy of monitoring and locating the fault 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:
respectively taking the head end and the tail end of the power distribution network and the tail ends of all branches as monitoring points to monitor the traveling wave signals;
for each of the monitoring points: taking the monitoring point as a root node, taking the power distribution network node as a branch node, taking the other monitoring points as leaf nodes, and constructing a monitoring tree by taking an actual line of the power distribution network as a branch connecting each node;
collecting fault traveling wave signals received by each monitoring point in response to the occurrence of a power distribution network fault, and obtaining first distances from each monitoring point to the fault point respectively according to the fault traveling wave signals;
for each of the monitoring points: 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 failure branch set comprises a suspected failure branch and the distance from the failure point to the nodes at two ends of the suspected failure branch;
screening and recombining each first fault branch set to obtain a second fault branch set; at least one element in each first faulty branch set is regrouped into the second faulty branch set, the suspected faulty branch of each element in the second faulty branch set comprises a 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; selecting the maximum value in the judgment distances as a main judgment distance, and taking the rest judgment distances as secondary judgment distances;
according to
Obtaining a fault distance; wherein S is the fault distance, LmaxDetermine distance, L, for the mainiThe secondary judgment distance is determined, 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 is the number of the distances from the fault point corresponding to the primary judgment distance to the first nodeiDetermining the number of the distances from the fault points corresponding to the secondary judgment distance to the first node;
and acquiring the specific position of the fault point in the power distribution network according to the suspected fault branch corresponding to the main judgment distance and the fault distance.
Optionally, the obtaining a specific position of the fault point on the power distribution network according to the suspected fault branch corresponding to the main judgment distance and the fault distance includes:
determining the suspected fault branch corresponding to the main judgment distance as a fault existing branch;
and confirming the position of the fault existing branch extending the fault distance from the first node to the center of the fault existing branch as the specific position of the fault point on the power distribution network.
Optionally, the taking the actual line of the power distribution network as a branch connecting each node includes:
and reducing the actual line between the monitoring point and the power distribution network node in the power distribution network according to a preset proportion, and then using the actual line as a branch connecting each node in the monitoring tree.
Optionally, before acquiring the received fault traveling wave signal of each monitoring point and obtaining the first distance from each monitoring point to the fault point according to the fault traveling wave signal, the method further includes:
and in response to the occurrence of the fault of the power distribution network, 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 includes:
when the power distribution network has no fault, injecting a first traveling wave signal into the head end of the power distribution network, and recording a first time point;
collecting the time when other monitoring points except the head end receive the first traveling wave signal, and recording the time as a plurality of second time points;
and acquiring 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 a 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 to
Obtaining the propagation speed of the traveling wave in the power distribution network; wherein v is the propagation speed of the traveling wave in the power distribution network, T1At a first point in time, TbIs the second time point, b is the number of the second time point and b > 0, a is the number of the second time point, LbAnd the actual line distance from the monitoring point corresponding to the second time to the head end.
Optionally, the method further includes:
and a traveling wave signal measuring and taking device for monitoring traveling wave signals is arranged at each monitoring point.
The invention has the beneficial effects that: 1. the method monitors the traveling wave signals by respectively taking the head end and the tail end of the power distribution network and the tail ends of all branches as monitoring points; for each monitoring point: taking the monitoring point as a root node, the power distribution network node as a branch node, the rest monitoring points as leaf nodes, and the actual line of the power distribution network as a branch connecting each node to construct a monitoring tree; collecting fault traveling wave signals received by each monitoring point in response to the occurrence of a power distribution network fault, and obtaining first distances from each monitoring point to the fault point respectively according to the fault traveling wave signals; 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 failure branch set comprises a suspected failure branch and the distance from a failure point to nodes at two ends of the suspected failure branch. According to the invention, the monitoring tree is constructed 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 used for the power distribution network after being established. Compared with the prior art that each endpoint is traversed for calculation, the method and the device can effectively improve the power distribution network fault monitoring and positioning efficiency. In addition, the monitoring tree of the invention can also intuitively embody the position of the fault point. 2. Screening and recombining each first fault branch set to obtain a second fault branch set; in the second failure branch setAdding distances from fault points to a first node in the elements with the same suspected branches to obtain a plurality of judgment distances; selecting the maximum value in the judgment distances as a main judgment distance, and taking the rest judgment distances as secondary judgment distances; according to
Obtaining a fault distance; and acquiring the specific position of a fault point in the power distribution network according to the suspected fault branch and the fault distance corresponding to the main judgment distance. According to the method, all elements of the second fault branch set are adopted to carry out error reduction calculation on the fault distance, and compared with the prior art that only two end points are adopted for calculation, the position of the fault point obtained by the method cannot be greatly influenced due to the deviation of one element, so that the position of the fault point is ensured to be more accurate. 3. The invention reduces the actual line between the monitoring point in the power distribution network and the nodes of the power distribution network according to the preset proportion, and then the actual line is used as a branch connecting each node in the monitoring tree. The invention reduces the actual line according to the preset proportion and then uses the reduced actual line as a branch for connecting each node in the monitoring tree, thereby ensuring that the position of the fault point of the monitoring tree is more visual and obvious. 4. When the power distribution network has no fault, injecting a first traveling wave signal into the head end of the power distribution network, and recording a first time point; collecting the time when other monitoring points except the head end receive the first traveling wave signal, and recording the time as a plurality of second time points; and acquiring 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 precision of the obtained propagation speed is ensured by averaging 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, and calculates the elements in the second fault branch set, thereby obtaining 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 diagram 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 with 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 using 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 using 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 using 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 using 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, which can be realized by appropriately improving technical details by taking the contents of the text as reference by a person skilled in the art. It is expressly intended that all such similar substitutes and modifications which would be obvious to one skilled in the art are deemed to be included in the invention. While the methods and applications of this invention have been described in terms of preferred embodiments, it will be apparent to those of ordinary skill in the art that variations and modifications in the methods and applications described herein, as well as other suitable variations and combinations, may be made to implement and use the techniques of this invention without departing from the spirit and scope of the invention.
The applicant researches and discovers that: in a multi-terminal power distribution network, the time difference of traveling waves arriving at different measuring terminals is often accurately positioned, namely, the positioning by a double-terminal method. The double-end method is applied to fault monitoring and positioning of a multi-end power distribution network, two different ends are required to be selected as traveling wave monitoring ends to calculate whether a fault occurs on a line between the two selected ends, and the two ends are continuously selected in a traversal mode until the fault is positioned. The double-end method is applied to a multi-end power distribution network, and because each end point needs to be traversed continuously, the efficiency is low; and when the fault is positioned, only the 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 the positioning result.
Therefore, the embodiment of the invention discloses a power distribution network fault monitoring method, as shown in fig. 1, the method comprises the following steps:
step S101: and respectively taking the head end and the tail end of the power distribution network and the tail ends of all the branches as monitoring points to monitor the traveling wave signals.
Optionally, the method further comprises:
and a traveling wave signal measuring and taking device for monitoring traveling wave signals is arranged at each monitoring point.
A traveling wave (traveling wave) refers to a transmission state of a plane wave on a transmission line, and the amplitude of the traveling wave changes exponentially along the propagation direction, and the phase changes linearly along the transmission line.
Step S102: for each monitoring point: and taking the monitoring point as a root node, the power distribution network node as a branch node, the rest monitoring points as leaf nodes, and the actual line of the power distribution network as a branch connecting each node to construct a monitoring tree.
It is worth mentioning that the nodes are the cross points of the branches of the distribution network, the nodes are the nodes of the tree, and the two nodes have the same pronunciation but different meanings.
Optionally, taking an actual line of the power distribution network as a branch connecting each node, includes:
and reducing the actual line between the monitoring point in the power distribution network and the nodes of the power distribution network according to a preset proportion, and then taking the actual line as a branch connecting each node in the monitoring tree.
It should be noted that, by constructing the monitoring tree, the embodiment of the present invention can more intuitively and quickly identify the location of the fault point.
Step S103: and responding to the occurrence of the power distribution network fault, acquiring fault traveling wave signals received by each monitoring point, and acquiring first distances from each monitoring point to the fault point respectively according to the fault traveling wave signals. The first distance is the distance from the monitoring point to the fault point.
Optionally, before acquiring the received fault traveling wave signal of each monitoring point and obtaining the first distance from each monitoring point to the fault point according to the fault traveling wave signal, the method further includes:
and responding to the occurrence of the power distribution network fault, and 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 determined by a single-ended method, i.e. by measuring the round-trip time of the fault travelling wave at the fault point and the measuring end.
Specifically, for example, when the time point of injecting the initial traveling wave signal at the measuring end is 27 μ s, the time point of receiving the fault traveling wave signal is 28 μ s, and the traveling wave propagation speed is 300000km/s, the fault distance is 3 × 108×(28-27)×10-6＝300m。
In the embodiment of the present invention, the first distances from the monitoring points to the fault point are not limited to be obtained by using a single-end method, and the first distances may be obtained by using other methods, so long as the first distances do not depart from the concept of the present invention, the first distances can be regarded as the protection scope of the present invention.
Step S104: for each monitoring point: and 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 failure branch set comprises a suspected failure branch and the distance from a failure point to nodes at two ends of the suspected failure branch.
It should be noted that the suspected fault branch is a branch where a fault point may exist, for example, a monitoring point O is calculated1First distance to failure point 300m, branch O1O2And branch O1O3Are all 500m, then branch O1O2And branch O1O3Is a suspected faulty branch.
In particular, the first faulty branch setThe elements in the synthesis can be represented as [ O ]1O2,300m,200m]，O1O2For indicating a suspected faulty branch, O1And O2Is the two-end node of two suspected fault branches, and 300m is from fault point to O1200m is the point of failure to O2The distance of (c).
Step S105: screening and recombining each first fault branch set to obtain a second fault branch set; at least one element in each first failure branch set is recombined into a second failure branch set, suspected failure branches of each element in the second failure branch set comprise the same node, and the node is called a first node.
Specifically, if the first fault branch set is set 1, set 2, and set 3, and set 1, set 2, and set 3 respectively are:
{[O1O2,300m,200m],[O3O4,75m,120m],[O3O5,75m,220m]}
{[O6O7,100m,70m],[O8O9,65m,220m],[O1O3,35m,120m]}
{[O10O11,100m,70m],[O10O12,65m,220m],[O1O4,295m,220m]}
screening out the three sets which all comprise the same node O1By recombination, i.e. the element [ O ]1O2,300m,200m]，[O1O3,35m,120m]And [ O1O4,295m,220m]And obtaining a second fault branch set: { [ O ]1O2,300m,200m],[O1O3,35m,120m],[O1O4,295m,220m]}。
In the above set, there are generally no other nodes between nodes at both ends of all branches, but there are exceptions, as follows:
such as O1As a first node, leave O in the faulty branch1The longest node distance is 300m, where O1With no other node but a first failureIn the set of branches, e.g., { [ O ]2O3,50m,200m],[O3O4,75m,120m],[O3O5,75m,220m]Is not provided with node O1Element and also O1O2Is 200m, then 200+50<300, then can be regarded as O2O3Is also within the error range, the first fault branch is aggregated to { [ O ]1O3,250m,200m],[O3O4,75m,120m],[O3O5,75m,220m]}. It is worth mentioning that the method can be simplified if the first faulty branch set contains the first node.
Step S106: adding distances from fault points 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 in the judgment distances as a main judgment distance, and taking the rest judgment distances as secondary judgment distances.
For example, the second set of fault branches is:
{[O1O2,300m,200m],[O1O3,35m,120m],[O1O4,15m,220m],[O1O3,38m,118m],,[O1O2,298m,202m],}
is known to be O1In the first node, the primary determination distance is 300+298 m, 598m, and the secondary determination distances are 35+38, 73m, and 15m, respectively.
Step S107: according to
Obtaining a fault distance; wherein S is the fault distance, LmaxMainly determines the distance, LiThe distance is judged in a secondary mode, 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 is the number of the fault points corresponding to the primary judgment distancesiThe number of the distances from the fault point corresponding to the distance to the first node is judged in the next time.
It should be noted that the fault distance is obtained by comprehensively calculating a plurality of data, and has the characteristics of small error and high accuracy.
It should be noted that, in a specific application, an error needs to be prevented, the heating error prevention constant z, z is greater than 0, and the value range of the fault distance is [ S-z, S + z ].
Step S108: and acquiring the specific position of a 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 existing branch;
and confirming the position of the fault existing branch extending from the first node to the fault existing branch center for the fault distance 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, injecting a first traveling wave signal into the head end of the power distribution network, and recording a first time point;
collecting the time when other monitoring points except the head end receive the first traveling wave signal, and recording the time as a plurality of second time points;
and acquiring 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, 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, includes:
according to
Obtaining the propagation speed of the traveling wave in the power distribution network; wherein v is the propagation speed of the traveling wave in the power distribution network, T1At a first point in time, TbIs the second time point, b is the number of the second time point and b > 0, a is the number of the second time point, LbAnd the actual line distance from the monitoring point corresponding to the second time to the head end.
The following description is made with reference to 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 distribution network head end, F is a distribution network tail end, B, C, D and E are branch tail ends respectively, T1, T2, T3 and T4 are distribution network nodes, and each branch length is: AT1 is 300m, T1T2 is 300m, T2T3 is 300m, T3F is 300m, BT1 is 600m, CT2 is 600m, T3T4 is 300m, DT4 is 300m, and ET4 is 300 m.
The first distance from the fault point to monitor point a is 605m, then as shown in fig. 3, H in fig. 3 represents the fault point, H may exist in three branches BT1, CT2 and T2T3, and the first set of fault branches of monitor point a is { [ BT1, 305m, 295m ], [ CT2, 595m, 5m ], [ T2T3, 5m, 295m ] }.
The first distance from the fault point to monitor point B is 895m, then as shown in fig. 4, H in fig. 4 represents the fault point, H may exist in both branches AT1 and T1T2, and the first set of fault branches for monitor point B is { [ AT1, 5m, 295m ], [ T1T2, 295m, 5m ] }.
The first distance from the fault point to the monitoring point C is 603m, then as shown in fig. 5, H in fig. 5 represents the fault point, H may exist in two branches T1T2 and T2T3, and the first set of fault branches of the monitoring point C is { [ T1T2, 297m, 3m ], [ T2T3, 3m, 297m ] }.
The first distance from the fault point to the monitoring point D is 898m, then as shown in fig. 6, H in fig. 6 represents the fault point, H may exist in two branches 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, then as shown in fig. 7, H in fig. 7 represents the fault point, H may exist in two branches T1T2 and CT2, and the first fault branch set of the monitoring point E is { [ T1T2, 297m, 3m ], [ CT2, 597m, 3m ] }.
The first distance from the fault point to the monitoring point F is 604m, then as shown in fig. 3, H in fig. 3 represents the fault point, H may exist in three branches T1T2, CT2, DT4 and ET4, and the first fault branch set of the monitoring point F is { [ T1T2, 296m, 4m ], [ CT2, 596m, 4m ], [ DT4, 296m, 4m ], [ ET4, 296m, 4m ] }.
According to the first embodiment, it is determined that each first set of faulty branches has an element containing node T2, and that T2 is determined as a first node, then there are second sets of faulty branches as { [ CT2, 595m, 5m ], [ T2T3, 5m, 295m ], [ T1T2, 295m, 5m ], [ T1T2, 297m, 3m ], [ T2T3, 3m, 297m ], [ T2T3, 2m, 298m ], [ T1T2, 297m, 3m ], [ CT2, 597m, 3m ], [ T1T2, 296m, 4m ], [ CT2, 596m, 4m ] }.
The distances from the fault point in the fault branch T1T2 to the first node are added, i.e. 5+3+3+4 equals 15 m. The distances from the fault point of the fault branch T2T3 to the first node are added, i.e. 5+3+2 equals 10 m. The distances from the fault point of the fault branch CT2 to the first node are added, i.e. 5+3+4 equals 12 m.
15m, 10m and 12m are obtained as judgment distances, 15m is a main judgment distance, and the rest judgment distances are secondary judgment distances.
According to
The failure distance S of the first embodiment was found to be 0.57 m.
The fault point of the first embodiment is located on branch T1T2 and is 0.57m from T2.
In specific application, error is also prevented, and 0.5m is taken as an error prevention parameter, so that the distance between the fault point and T2 is [0.07m, 1.07m ].
The embodiment of the invention monitors the traveling wave signal by respectively taking the head end and the tail end of the power distribution network and the tail end of each branch as monitoring points; for each monitoring point: taking the monitoring point as a root node, the power distribution network node as a branch node, the rest monitoring points as leaf nodes, and the actual line of the power distribution network as a branch connecting each node to construct a monitoring tree; collecting fault traveling wave signals received by each monitoring point in response to the occurrence of a power distribution network fault, and obtaining first distances from each monitoring point to the fault point respectively according to the fault traveling wave signals; for each monitoring point: substituting the first distance corresponding to the monitoring point into the monitoring tree of the monitoring point to obtain the eventA first fault branch set of the barrier point on the monitoring tree of the monitoring point; each element in the first failure branch set comprises a suspected failure branch and the distance from a failure point to nodes at two ends of the suspected failure branch. According to the embodiment of the invention, the monitoring tree is constructed 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 in the power distribution network, and the monitoring tree of the embodiment of the invention can be used for the power distribution network after being established. Compared with the prior art that calculation is performed by traversing each endpoint, the method and the device for monitoring and positioning the power distribution network fault can effectively improve the efficiency of monitoring and positioning the power distribution network fault. In addition, the monitoring tree of the embodiment of the invention can also intuitively embody the position of the fault point. Screening and recombining each first fault branch set to obtain a second fault branch set; adding distances from fault points 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; selecting the maximum value in the judgment distances as a main judgment distance, and taking the rest judgment distances as secondary judgment distances; according to
Obtaining a fault distance; and acquiring the specific position of a fault point in the power distribution network according to the suspected fault branch and the fault distance corresponding to the main judgment distance. In the embodiment of the invention, error reduction calculation is carried out on the fault distance by adopting all the elements of the second fault branch set, and compared with the prior art which only adopts two end points for calculation, the position of the fault point obtained by the embodiment of the invention cannot be greatly influenced by the deviation of one element, thereby ensuring that the position of the obtained fault point is more accurate. The embodiment of the invention reduces the actual line between the monitoring point in the power distribution network and the node of the power distribution network according to the preset proportion, and then the actual line is used as a branch connecting each node in the monitoring tree. According to the embodiment of the invention, the actual line is reduced according to the preset proportion and then is used as a branch for connecting each node in the monitoring tree, so that the position of the fault point of the monitoring tree can be ensured to be more visual and obvious. According to the embodiment of the invention, when the power distribution network has no fault, the first traveling wave signal is injected to the head end of the power distribution network, and the first time is recordedPoint; collecting the time when other monitoring points except the head end receive the first traveling wave signal, and recording the time as a plurality of second time points; and acquiring 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 self, so that inaccuracy caused by directly adopting the light speed is avoided, and the propagation speed accuracy is ensured by averaging the propagation speeds obtained at different monitoring ends. In summary, the embodiment of 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, and calculates the elements in the second fault branch set, thereby obtaining the specific position of the fault point in the power distribution network.
It is noted that, herein, relational terms such as first and second, and the like may be 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. Also, 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 an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
All the embodiments in the present specification are described in a related manner, and the same and similar parts among the embodiments may be referred to each other, and each embodiment focuses on the differences from the other embodiments. In particular, for the system embodiment, since it is substantially similar to the method embodiment, the description is simple, and for the relevant points, reference may be made to the partial description of the method embodiment.
The above description is only for the preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention shall fall within the protection scope of the present invention.
Claims (7)
1. A power distribution network fault monitoring method is characterized by comprising the following steps:
respectively taking the head end and the tail end of the power distribution network and the tail ends of all branches as monitoring points to monitor the traveling wave signals;
for each of the monitoring points: taking the monitoring point as a root node, taking the power distribution network node as a branch node, taking the other monitoring points as leaf nodes, and constructing a monitoring tree by taking an actual line of the power distribution network as a branch connecting each node;
collecting fault traveling wave signals received by each monitoring point in response to the occurrence of a power distribution network fault, and obtaining first distances from each monitoring point to the fault point respectively according to the fault traveling wave signals;
for each of the monitoring points: 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 failure branch set comprises a suspected failure branch and the distance from the failure point to the nodes at two ends of the suspected failure branch;
screening and recombining each first fault branch set to obtain a second fault branch set; at least one element in each first faulty branch set is regrouped into the second faulty branch set, the suspected faulty branch of each element in the second faulty branch set comprises a 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; selecting the maximum value in the judgment distances as a main judgment distance, and taking the rest judgment distances as secondary judgment distances;
according to
Obtaining a fault distance; wherein S is the fault distance, LmaxDetermine distance, L, for the mainiThe secondary judgment distance is determined, 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 is the number of the distances from the fault point corresponding to the primary judgment distance to the first nodeiDetermining the number of the distances from the fault points corresponding to the secondary judgment distance to the first node;
and acquiring the specific position of the fault point in the power distribution network according to the suspected fault branch corresponding to the main judgment distance and the fault 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 corresponding to the main judgment distance and the fault distance comprises:
determining the suspected fault branch corresponding to the main judgment distance as a fault existing branch;
and confirming the position of the fault existing branch extending the fault distance from the first node to the center of the fault existing branch as the specific position of the fault point on the power distribution network.
3. The method of claim 1, wherein said taking actual lines of said power distribution network as branches connecting nodes comprises:
and reducing the actual line between the monitoring point and the power distribution network node in the power distribution network according to a preset proportion, and then using the actual line as a branch connecting each node in the monitoring tree.
4. The method according to claim 1, wherein the received fault traveling wave signal of each monitoring point is collected, and before the first distance from each monitoring point to the fault point is obtained according to the fault traveling wave signal, the method further comprises:
and in response to the occurrence of the power distribution network fault, injecting the initial traveling wave signal from each monitoring point, wherein the initial traveling wave signal is an incident wave of the fault traveling wave signal.
5. The method of claim 1, further comprising:
when the power distribution network has no fault, injecting a first traveling wave signal into the head end of the power distribution network, and recording a first time point;
collecting the time when other monitoring points except the head end receive the first traveling wave signal, and recording the time as a plurality of second time points;
and acquiring 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 of claim 5, wherein said obtaining a propagation speed of a traveling wave in said power distribution network based on said first point in time, a plurality of said second points in time, and actual line distances from said head end to other of said monitoring points comprises:
according to
Obtaining the propagation speed of the traveling wave in the power distribution network; wherein v is the propagation speed of the traveling wave in the power distribution network, T1At a first point in time, TbIs the second time point, b is the number of the second time point and b > 0, a is the number of the second time point, LbAnd the actual line distance from the monitoring point corresponding to the second time to the head end.
7. The method of claim 1, further comprising:
and a traveling wave signal measuring and taking device for monitoring traveling wave signals is arranged at each monitoring point.
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