CN113433417B - Power distribution network fault positioning method and system based on measured voltage difference - Google Patents
Power distribution network fault positioning method and system based on measured voltage difference Download PDFInfo
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- CN113433417B CN113433417B CN202110501581.7A CN202110501581A CN113433417B CN 113433417 B CN113433417 B CN 113433417B CN 202110501581 A CN202110501581 A CN 202110501581A CN 113433417 B CN113433417 B CN 113433417B
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- G—PHYSICS
- G01—MEASURING; TESTING
- 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
- G01R31/086—Locating faults in cables, transmission lines, or networks according to type of conductors in power transmission or distribution networks, i.e. with interconnected conductors
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- G—PHYSICS
- G01—MEASURING; TESTING
- 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
- G01R31/088—Aspects of digital computing
Abstract
The embodiment of the invention provides a power distribution network fault positioning method and system based on measured voltage difference, which are used for collecting voltage and current data before and after a power distribution network line fault by utilizing synchronous measuring devices arranged at a bus outlet and at a line tail end. And constructing a fault branch identification principle according to the measured voltage difference value and the calculated voltage difference value of the node of the synchronous measurement device before and after the fault. Furthermore, accurate positioning of a line fault point is achieved by combining voltage and current measurement data of a bus outlet and the tail end of a fault branch. The positioning method does not need to consider the global observability of the synchronous measuring device in the power distribution network, only needs to install the measuring devices at the bus outlet and the tail end of the line, and can realize the accurate fault positioning of the fault point. The fault positioning method has the advantages that the number of the power distribution network measuring devices is reduced, the fault positioning accuracy of the power distribution network is improved, and the fault positioning method is simple, practical and high in operability.
Description
Technical Field
The embodiment of the invention relates to the technical field of power distribution networks, in particular to a power distribution network fault positioning method and system based on measured voltage difference values.
Background
The power distribution network is used as a key part for directly connecting a power system and users, the circuit structure of the power distribution network is complex, and once a fault occurs, serious influence is caused on production and life of people. Therefore, how to accurately find the fault point and realize the quick positioning of the fault point have important significance.
At present, the common power distribution network fault positioning methods can be mainly divided into an impedance method, a traveling wave method and a method based on synchronous measurement data. The impedance method is simple and convenient, but is easily influenced by line parameters and the running state of the power distribution network. The traveling wave method utilizes fault traveling wave information generated by a line fault point, realizes the positioning of the fault point by analyzing refraction or reflection traveling waves collected by a line end, but needs to install a fault traveling wave collecting device at the tail end of the line, and the economical efficiency needs to be improved. Based on a synchronous data measurement method, fault location is carried out by utilizing voltage and current data acquired by a synchronous measurement device such as a mu PMU (phasor measurement unit), but the global observability of the measurement device in a power distribution network needs to be considered in the conventional method, and the fault location precision needs to be improved.
Disclosure of Invention
The embodiment of the invention provides a power distribution network fault positioning method and system based on measured voltage difference values, and aims to solve the problems that in the prior art, the positioning of a fault point needs a fault traveling wave acquisition device installed at the tail end of a line, so that the cost is high, and the fault positioning precision is low.
In a first aspect, an embodiment of the present invention provides a power distribution network fault location method based on a measured voltage difference, including:
determining power parameters at preset nodes on a power distribution network; the preset nodes comprise bus outlets and tail end nodes of all branches, and the electric parameters at least comprise measured voltage values;
determining the characteristic indexes of any preset node based on the calculated voltage values and the measured voltage values of the preset node before and after the fault and a preset characteristic index evaluation algorithm;
and determining the preset node with the maximum characteristic index, and judging the branch where the fault occurs at the preset node with the maximum characteristic index.
Preferably, the power parameter further includes a measurement current value and a measurement phase.
Preferably, the preset characteristic index evaluation algorithm is as follows:
Tt＝|(Utqc-Utfc)-(Utql-Utfl)|
wherein, TtIs a characteristic index of a preset node t, and t belongs to [1,2,3, …, n]N is the number of all preset nodes; u shapetqcAnd UtfcIndicating the calculated voltage value, U, of each of the preset nodes t before and after the faulttqlAnd UtflRepresenting the measured voltage values of the preset nodes t before and after the fault;
determining the preset node with the largest characteristic index, and judging the branch where the fault occurs at the preset node with the largest characteristic index, wherein the specific steps are as follows:
when the characteristic index T of the node m is presetmWhen the characteristic indexes of the nodes are larger than those of all other preset nodes, the following steps are carried out:
Tm/Tt＞1 t＝[1,2,3,...,n],t≠m
and judging that the fault occurs in the node branch where the preset node m is located.
Preferably, after determining the characteristic index of any preset node, the method further includes:
when the characteristic index T of the node m is presetmIs greater than the characteristic indexes of all the preset nodes at the upstream of the preset node m, and the characteristic indexes and T of the preset nodes exist at the downstream of the preset node mmWhen the node branches are equal, the node branches with the faults between the branch node corresponding to the preset node m and the branch node corresponding to the nearest upstream preset node are judged, namely:
where n represents the number of all preset nodes and δ represents an error factor.
Preferably, the calculated voltage values of the preset nodes t before and after the fault are respectively as follows:
[Utqc]＝[Zt][Iqt]
[Utfc]＝[Zt][Ift]
wherein Z istA node impedance matrix representing a predetermined node t during normal operation of the distribution network, i.e. a measured node impedance matrix, Iqt,IftAnd respectively representing the current data collected at the preset node t before and after the fault.
Preferably, after determining that the fault occurs in the branch where the preset node with the largest characteristic index is located, or determining that the fault occurs in the node branch between the branch node corresponding to the preset node m and the branch node corresponding to the nearest upstream preset node, the method further includes:
determining a head end node I and a tail end node j of a node branch with a fault, and based on the difference value of the voltage difference values measured before and after the fault of the tail end node j and the injection current IfcObtaining the node with the minimum voltage difference value in the line between the head end node i and the tail end node j, wherein the expression form is as follows:
wherein Q isj(t) represents the difference in voltage at different locations along the line between head end node i and tail end node j, Zji,ZjjRespectively representing element values I corresponding to a head end node I and a tail end node j in a measurement node impedance matrix during normal operation of the power distribution networkfcFor injecting current, Δ UjThe measured voltage difference value of the tail end node j before and after the fault, k represents the total dividing number of the circuit between the head end node i and the tail end node j, and l represents the dividing node number of the circuit;
obtaining the number L of divided nodes according to the node with the minimum voltage difference in the node branch with the fault, and calculating the fault distance L between the fault point f and the head end node ifComprises the following steps:
wherein L isijIndicating the length of the line between head end node i and end node j and k the total number of divisions of the line.
Preferably, the injection current expression is:
Ifc＝ΔIi+ΔIj
in the formula,. DELTA.Ii,ΔIjRespectively representing the current change values, U, of the head end node i and the tail end node j after the faulti,UfiRespectively representing measured voltage values, U, of head-end node i before and after a faultj,UfjRepresenting the measured voltage values, Z, of the end node j before and after the fault, respectivelyii,Zij,Zji,ZjjRespectively represents the pairs of a head end node i and a tail end node j in the impedance matrix of the measuring node in normal operationThe corresponding element value.
In a second aspect, an embodiment of the present invention provides a power distribution network fault location system based on a measured voltage difference, including:
the measuring module is used for determining power parameters at preset nodes on the power distribution network; the preset nodes comprise bus outlets and tail end nodes of all branches, and the electric power parameters at least comprise measured voltage values;
the index calculation module is used for determining the characteristic indexes of any preset node based on the calculated voltage values and the measured voltage values of the preset node before and after the fault and a preset characteristic index evaluation algorithm;
and the fault positioning module is used for determining the preset node with the maximum characteristic index and judging the branch where the fault occurs at the preset node with the maximum characteristic index.
In a third aspect, an embodiment of the present invention provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, where the processor executes the computer program to implement the steps of the power distribution network fault location method based on measured voltage difference values according to the embodiment of the first aspect of the present invention.
In a fourth aspect, an embodiment of the present invention provides a non-transitory computer-readable storage medium, on which a computer program is stored, where the computer program, when executed by a processor, implements the steps of the method for fault location of a power distribution network based on measured voltage difference according to an embodiment of the first aspect of the present invention.
According to the power distribution network fault positioning method and system based on the measured voltage difference, voltage and current data before and after a power distribution network line fault are acquired by using synchronous measuring devices installed at a bus outlet and at a line tail end. And constructing a fault branch identification principle according to the measured voltage difference value and the calculated voltage difference value of the node of the synchronous measurement device before and after the fault. Furthermore, accurate positioning of a line fault point is achieved by combining voltage and current measurement data of a bus outlet and the tail end of a fault branch. The positioning method of the invention does not need to consider the global observability of the synchronous measuring device in the power distribution network, only needs to install the measuring devices at the bus outlet and the line tail end, and can realize the accurate fault positioning of the fault point. The fault positioning method has the advantages that the number of the power distribution network measuring devices is reduced, the fault positioning accuracy of the power distribution network is improved, and the fault positioning method is simple, practical and high in operability.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and those skilled in the art can also obtain other drawings according to the drawings without creative efforts.
FIG. 1 is a block diagram of a fault location process according to an embodiment of the invention;
fig. 2 is a topology diagram of a power distribution network structure according to an embodiment of the present invention;
fig. 3 is a schematic physical structure diagram according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In the embodiment of the present application, the term "and/or" is only one kind of association relationship describing an associated object, and means that three relationships may exist, for example, a and/or B may mean: a exists alone, A and B exist simultaneously, and B exists alone.
The terms "first" and "second" in the embodiments of the present application are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present application, the terms "comprise" and "have", as well as any variations thereof, are intended to cover a non-exclusive inclusion. For example, a system, product or apparatus that comprises a list of elements or components is not limited to only those elements or components but may alternatively include other elements or components not expressly listed or inherent to such product or apparatus. In the description of the present application, "plurality" means at least two, e.g., two, three, etc., unless explicitly specifically limited otherwise.
Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearances of the phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. It is explicitly and implicitly understood by one skilled in the art that the embodiments described herein can be combined with other embodiments.
At present, the common power distribution network fault positioning methods can be mainly divided into an impedance method, a traveling wave method and a method based on synchronous measurement data. The impedance method is simple and convenient, but is easily influenced by line parameters and the running state of the power distribution network. The traveling wave method utilizes fault traveling wave information generated by a line fault point, realizes the positioning of the fault point by analyzing refraction or reflection traveling waves collected by a line end, but needs to install a fault traveling wave collecting device at the tail end of the line, and the economical efficiency needs to be improved. The method based on synchronous measurement data carries out fault location by utilizing voltage and current data acquired by a synchronous measurement device such as a mu PMU (phasor measurement Unit), but the current method needs to consider the global observability of the measurement device in the power distribution network, and the fault location precision needs to be improved.
Therefore, the embodiment of the invention provides a power distribution network fault positioning method and system based on measured voltage difference, wherein voltage and current synchronous measuring devices are installed at a bus outlet and a line tail end node of a power distribution network, a fault branch judgment principle is established by utilizing data collected by each synchronous measuring device before and after a fault, and a fault point is accurately positioned according to the measured data of the fault branch tail end measuring device and the bus outlet. The following description and description will proceed with reference being made to various embodiments.
Fig. 1 to fig. 2 provide a distribution network fault location method based on measured voltage difference values according to an embodiment of the present invention, including:
determining power parameters at preset nodes on a power distribution network; the preset nodes comprise bus outlets and tail end nodes of all branches, and the electric power parameters at least comprise measured voltage values;
determining the characteristic indexes of any preset node based on the calculated voltage values and the measured voltage values of the preset node before and after the fault and a preset characteristic index evaluation algorithm;
and determining the preset node with the maximum characteristic index, and judging the branch where the fault occurs at the preset node with the maximum characteristic index.
Specifically, voltage and current synchronous measuring devices are installed at a bus outlet and a line tail end node of the power distribution network, a fault branch judgment principle is established by utilizing data collected by each synchronous measuring device before and after a fault, and a fault point is accurately positioned according to the measuring data of the tail end measuring device of a fault branch and the bus outlet. In this embodiment, the branch circuit is a circuit between the end node of the circuit including the measurement device and the branch node of the circuit; the node branch is a branch between branch nodes of the line, and a branch between a measuring device node and a branch node at a bus outlet.
The method realizes the recording of the amplitude and phase data of the voltage and the current at the nodes of the power distribution network, and is not limited to a micro synchronous vector measurement unit (mu PMU).
On the basis of the above embodiment, as a preferred implementation, the preset feature index evaluation algorithm is:
Tt＝|(Utqc-Utfc)-(Utql-Utfl)|
wherein, TtIs a characteristic index of a preset node t, and t belongs to [1,2,3, …, n]N is the number of all preset nodesAn amount; u shapetqcAnd UtfcIndicating the calculated voltage value, U, of each of the preset nodes t before and after the faulttqlAnd UtflRepresenting the measured voltage values of the preset nodes t before and after the fault;
determining the preset node with the largest characteristic index, and judging the branch where the fault occurs at the preset node with the largest characteristic index, wherein the specific steps are as follows:
when the characteristic index T of the node m is presetmWhen the characteristic indexes of the nodes are larger than those of all other preset nodes, the following steps are carried out:
Tm/Tt＞1 t＝[1,2,3,...,n],t≠m
and judging that the fault occurs in the node branch where the preset node m is located.
Fig. 1 shows a fault location process of the present invention, and fig. 2 is a topology diagram of a power distribution network structure. In fig. 2, the node 1, the node 18, the node 22, the node 25 and the node 33 are provided with synchronous measuring devices for collecting voltage and current data at the nodes. The branch branches in the system are respectively M2M22，M3M25， M6M18And M6M33The node branches are respectively M1M2，M2M3And M3M6。
When line M between node 23 and node 2423M24When single-phase earth fault occurs, the distance between the fault point f and the node 3 occupies the branch M3M25Length L3-2550% of (i), i.e. df＝50％L3-25And the ground resistance is 200 omega. Firstly, calculating the characteristic index of each node as T by using a node characteristic index expression1，T18，T22，T25And T33Then comparing the sizes of the indexes of the characteristic values of different nodes to know the characteristic index T of the node 2525Maximum, greater than the characteristic indexes of the node 1, the node 18, the node 22 and the node 33, and meets the condition that the fault occurs in the branch M3M25Under the conditions of
T25/Tt＞1 t＝[1,18,22,33]
Therefore, it is determined that the fault occurs in the branch circuit M3M25。
On the basis of the foregoing embodiment, as a preferred implementation, after determining the characteristic index of any preset node, the method further includes:
when the characteristic index T of the node m is presetmIs greater than the characteristic indexes of all the preset nodes at the upstream of the preset node m, and the characteristic indexes and T of the preset nodes exist at the downstream of the preset node mmWhen the node branch is equal, the fault is judged to occur in the node branch between the branch node corresponding to the preset node m and the branch node corresponding to the nearest upstream preset node, namely:
where n represents the number of all preset nodes and δ represents an error factor.
On the basis of the above embodiment, as a preferred implementation manner, the calculated voltage values of the preset nodes t before and after the fault are respectively:
[Utqc]＝[Zt][Iqt]
[Utfc]＝[Zt][Ift]
wherein Z istNode impedance matrix representing preset nodes t during normal operation of the distribution network, i.e. measured node impedance matrix, Iqt,IftAnd respectively representing the current data collected at the preset node t before and after the fault.
Calculating the injection current I by using the data collected from the head end node 1 of the fault-containing line and the tail end node 25 of the branchfcComprises the following steps:
Ifc＝ΔI1+ΔI25
in the formula of U1,Uf1Respectively representing the voltage values of the node 1 before and after a fault，U25,Uf25Representing the voltage values, Z, of the node 25 before and after the fault, respectivelyM1M1，ZM1M25，ZM25M1，ZM25M25Respectively representing the corresponding element values of node 1 and node 25 in the measurement node impedance matrix in normal operation.
On the basis of the foregoing embodiment, as a preferred implementation manner, after determining that the fault occurs in the branch circuit where the preset node with the largest characteristic indicator is located, or determining that the fault occurs in the node branch circuit between the branch node corresponding to the preset node m and the branch node corresponding to the nearest upstream preset node, the method further includes:
determining a head end node I and a tail end node j of a node branch with a fault, and based on the difference value of the voltage difference values measured before and after the fault of the tail end node j and the injection current IfcObtaining the node with the minimum voltage difference value in the line between the head end node i and the tail end node j, wherein the expression form is as follows:
wherein Q isj(t) represents the difference in voltage at different locations of the line between head end node i and tail end node j, Zji,ZjjRespectively representing element values I corresponding to a head end node I and a tail end node j in a measurement node impedance matrix during normal operation of the power distribution networkfcFor injecting current, Δ UjThe measured voltage difference value of the tail end node j before and after the fault, k represents the total dividing number of the circuit between the head end node i and the tail end node j, and l represents the dividing node number of the circuit;
obtaining the number L of divided nodes according to the node with the minimum voltage difference in the node branch with the fault, and calculating the fault distance L between the fault point f and the head end node ifComprises the following steps:
wherein L isijRepresenting head end nodes i and endThe length of the line between end nodes j, k represents the total number of divisions of the line.
The node with the smallest voltage difference in the line between node 3 and node 25 is obtained as l-49%.
Calculating the fault distance L between the fault point f and the node 3fIs composed of
Lf＝48％L3-25
Thus, 50% L compared to the actual fault distance3-25The fault point positioning error is 2%, and the requirement of accurate positioning is met within the error allowable range.
Preferably, the injection current expression is:
Ifc＝ΔIi+ΔIj
in the formula,. DELTA.Ii,ΔIjRespectively representing the current change values, U, of the head end node i and the tail end node j after the faulti,UfiRespectively representing measured voltage values, U, of head-end node i before and after a faultj,UfjRepresenting the measured voltage values, Z, of the end node j before and after the fault, respectivelyii,Zij,Zji,ZjjAnd respectively representing element values corresponding to a head end node i and a tail end node j in the measurement node impedance matrix in normal operation.
When the line M between the node 4 and the node 54M5When two-phase earth fault occurs, the distance between the fault point f and the node 3 accounts for the branch M3M6Length L3-640% of (i), i.e. df＝40％L3-6And the ground resistance is 200 omega. Firstly, calculating the characteristic index of each node as T by using a node characteristic index expression1，T18，T22，T25And T33Then comparing the different node characteristic value indexes to know the characteristic index T of the node 3333Is greater than the characteristic indexes of the upstream node 1, the node 22 and the node 25 and equal to the characteristic index of the downstream node 18 of the node 33, and meets the requirementsThe fault occurs at the branch node M corresponding to the node 33 and the nearest upstream node 25 thereof6And M3Node branch M between3M6The conditions of (a) are as follows:
therefore, it is determined that the fault occurs in the branch circuit M3M6。
Calculating the injection current I by using the data collected from the head end node 1 of the fault-containing line and the tail end node 33 of the branchfcComprises the following steps:
Ifc＝ΔI1+ΔI33
in the formula of U1,Uf1Respectively representing the voltage values, U, of the node 1 before and after a fault33,Uf33Representing the voltage values, Z, of the nodes 33 before and after the fault, respectivelyM1M1，ZM1M33，ZM33M1，ZM33M33Respectively representing the corresponding element values of node 1 and node 33 in the measurement node impedance matrix in normal operation.
Further, the node where the voltage difference between the lines between the node 3 and the node 6 is the smallest is obtained as l 44%.
Further, a failure distance L between the failure point f and the node 3 is calculatedfComprises the following steps:
Lf＝43％L3-6
thus, 43% L compared to the actual fault distance3-6The fault point positioning error is 3%, and the requirement of accurate positioning is met within the error allowable range.
In a second aspect, an embodiment of the present invention provides a power distribution network fault location system based on measured voltage difference values, where the power distribution network fault location method based on measured voltage difference values in the above embodiments includes:
the measuring module is used for determining power parameters at preset nodes on the power distribution network; the preset nodes comprise bus outlets and tail end nodes of all branches, and the electric power parameters at least comprise measured voltage values;
the index calculation module is used for determining the characteristic indexes of any preset node based on the calculated voltage values and the measured voltage values of the preset node before and after the fault and a preset characteristic index evaluation algorithm;
and the fault positioning module is used for determining the preset node with the maximum characteristic index and judging the branch where the fault occurs at the preset node with the maximum characteristic index.
Based on the same concept, an embodiment of the present invention further provides an entity structure schematic diagram, as shown in fig. 3, the server may include: a processor (processor)810, a communication Interface 820, a memory 830 and a communication bus 840, wherein the processor 810, the communication Interface 820 and the memory 830 communicate with each other via the communication bus 840. The processor 810 may invoke logic instructions in the memory 830 to perform the steps of the method for power distribution network fault location based on measured voltage difference values as described in the various embodiments above. Examples include:
determining power parameters at preset nodes on a power distribution network; the preset nodes comprise bus outlets and tail end nodes of all branches, and the electric power parameters at least comprise measured voltage values;
determining the characteristic indexes of any preset node based on the calculated voltage values and the measured voltage values of the preset node before and after the fault and a preset characteristic index evaluation algorithm;
and determining the preset node with the maximum characteristic index, and judging the branch where the fault occurs at the preset node with the maximum characteristic index.
In addition, the logic instructions in the memory 830 may be implemented in software functional units and stored in a computer readable storage medium when the logic instructions are sold or used as independent products. Based on such understanding, the technical solution of the present invention may be embodied in the form of a software product, which is stored in a storage medium and includes instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the method according to the embodiments of the present invention. And the aforementioned storage medium includes: a U-disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and other various media capable of storing program codes.
Based on the same concept, embodiments of the present invention further provide a non-transitory computer-readable storage medium, where a computer program is stored, where the computer program includes at least one code, and the at least one code is executable by a master control device to control the master control device to implement the steps of the distribution network fault location method based on measured voltage difference according to the embodiments. Examples include:
determining power parameters at preset nodes on a power distribution network; the preset nodes comprise bus outlets and tail end nodes of all branches, and the electric power parameters at least comprise measured voltage values;
determining the characteristic indexes of any preset node based on the calculated voltage values and the measured voltage values of the preset node before and after the fault and a preset characteristic index evaluation algorithm;
and determining the preset node with the maximum characteristic index, and judging the branch where the fault occurs at the preset node with the maximum characteristic index.
Based on the same technical concept, the embodiment of the present application further provides a computer program, which is used to implement the above method embodiment when the computer program is executed by the main control device.
The program may be stored in whole or in part on a storage medium packaged with the processor, or in part or in whole on a memory not packaged with the processor.
Based on the same technical concept, the embodiment of the present application further provides a processor, and the processor is configured to implement the above method embodiment. The processor may be a chip.
In summary, the power distribution network fault location method and system based on voltage difference measurement provided by the embodiments of the present invention collect voltage and current data before and after a power distribution network line fault by using synchronous measurement devices installed at a bus outlet and a line end. And constructing a fault branch identification principle according to the measured voltage difference value and the calculated voltage difference value of the node of the synchronous measurement device before and after the fault. Furthermore, accurate positioning of a line fault point is achieved by combining voltage and current measurement data of a bus outlet and the tail end of a fault branch. The positioning method of the invention does not need to consider the global observability of the synchronous measuring device in the power distribution network, only needs to install the measuring devices at the bus outlet and the line tail end, and can realize the accurate fault positioning of the fault point. The fault positioning method has the advantages that the number of the power distribution network measuring devices is reduced, the fault positioning accuracy of the power distribution network is improved, and the fault positioning method is simple, practical and high in operability.
The embodiments of the present invention can be arbitrarily combined to achieve different technical effects.
In the above embodiments, all or part of the implementation may be realized by software, hardware, firmware, or any combination thereof. When implemented in software, may be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the processes or functions described in the present application are generated in whole or in part. The computer may be a general purpose computer, a special purpose computer, a network of computers, or other programmable device. The computer instructions may be stored in a computer readable storage medium or transmitted from one computer readable storage medium to another, for example, the computer instructions may be transmitted from one website, computer, server, or data center to another website, computer, server, or data center by wire (e.g., coaxial cable, fiber optic, digital subscriber line) or wirelessly (e.g., infrared, wireless, microwave, etc.). The computer-readable storage medium can be any available medium that can be accessed by a computer or a data storage device, such as a server, a data center, etc., that incorporates one or more of the available media. The usable medium may be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium (e.g., Solid state disk), among others.
One of ordinary skill in the art will appreciate that all or part of the processes in the methods of the above embodiments may be implemented by hardware related to instructions of a computer program, which may be stored in a computer-readable storage medium, and when executed, may include the processes of the above method embodiments. And the aforementioned storage medium includes: various media capable of storing program codes, such as ROM or RAM, magnetic or optical disks, etc.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (9)
1. A power distribution network fault positioning method based on measured voltage difference is characterized by comprising the following steps:
determining power parameters at preset nodes on a power distribution network; the preset nodes comprise bus outlets and tail end nodes of all branches, and the electric power parameters at least comprise measured voltage values;
determining the characteristic indexes of any preset node based on the calculated voltage values and the measured voltage values of the preset node before and after the fault and a preset characteristic index evaluation algorithm; the preset characteristic index evaluation algorithm comprises the following steps:
Tt＝|(Utqc-Utfc)-(Utql-Utfl)|
wherein, TtFor presetting the characteristic index of the node t, t belongs to [1,2,3, …, n]N is the number of all preset nodes; u shapetqcAnd UtfcIndicating the calculated voltage value, U, of each of the preset nodes t before and after the faulttqlAnd UtflRepresenting the measured voltage values of the preset nodes t before and after the fault;
determining the preset node with the largest characteristic index, and judging the branch where the fault occurs at the preset node with the largest characteristic index, wherein the specific steps are as follows:
when the characteristic index T of the node m is presetmWhen the characteristic indexes of the nodes are larger than those of all other preset nodes, the following steps are carried out:
Tm/Tt＞1 t＝[1,2,3,...,n],t≠m
it is determined that the fault occurs in the node branch where the preset node m is located.
2. The method of claim 1, wherein the power parameters further comprise a measured current value and a measured phase.
3. The method of claim 1, wherein after determining the characteristic indicators of any of the predetermined nodes, the method further comprises:
when the characteristic index T of the node m is presetmIs greater than the characteristic indexes of all the preset nodes at the upstream of the preset node m, and the characteristic indexes and T of the preset nodes exist at the downstream of the preset node mmWhen the node branch is equal, the fault is judged to occur in the node branch between the branch node corresponding to the preset node m and the branch node corresponding to the nearest upstream preset node, namely:
where n represents the number of all preset nodes and δ represents an error factor.
4. The distribution network fault location method based on measured voltage difference values according to claim 3, wherein the calculated voltage values of each preset node t before and after the fault are respectively:
[Utqc]＝[Zt][Iqt]
[Utfc]＝[Zt][Ift]
wherein Z istA node impedance matrix representing a predetermined node t during normal operation of the distribution network, i.e. a measured node impedance matrix, Iqt,IftAnd respectively representing the current data collected at the preset node t before and after the fault.
5. The method according to claim 4, wherein after determining that the fault occurs in the branch circuit where the preset node with the largest characteristic index is located, or determining that the fault occurs in the node branch circuit between the branch node corresponding to the preset node m and the branch node corresponding to the nearest upstream preset node, the method further comprises:
determining a head end node I and a tail end node j of a node branch with a fault, and based on the difference value of the voltage difference values measured before and after the fault of the tail end node j and the injection current IfcObtaining the node with the minimum voltage difference value in the line between the head end node i and the tail end node j, wherein the expression form is as follows:
wherein Q isj(t) represents the difference in voltage at different locations of the line between head end node i and tail end node j, Zji,ZjjRespectively representing element values I corresponding to a head end node I and a tail end node j in a measurement node impedance matrix during normal operation of the power distribution networkfcFor injecting current, Δ UjThe measured voltage difference value of a tail end node j before and after the fault, k represents a line between a head end node i and the tail end node jThe total number of the divided lines, wherein l represents the number of the divided nodes of the line;
obtaining the number L of the divided nodes according to the node with the minimum voltage difference in the node branch with the fault, and calculating the fault distance L between the fault point f and the head end node ifComprises the following steps:
wherein L isijIndicating the length of the line between head end node i and end node j and k the total number of divisions of the line.
6. The method of claim 5, wherein the injection current expression is:
Ifc＝ΔIi+ΔIj
in the formula,. DELTA.Ii,ΔIjRespectively representing the current change values, U, of the head end node i and the tail end node j after the faulti,UfiRespectively representing measured voltage values, U, of head-end node i before and after a faultj,UfjRepresenting the measured voltage values, Z, of the end node j before and after the fault, respectivelyii,Zij,Zji,ZjjAnd respectively representing element values corresponding to a head end node i and a tail end node j in the measurement node impedance matrix in normal operation.
7. The utility model provides a distribution network fault location system based on measure voltage difference value which characterized in that includes:
the measuring module is used for determining power parameters at preset nodes on the power distribution network; the preset nodes comprise bus outlets and tail end nodes of all branches, and the electric power parameters at least comprise measured voltage values;
the index calculation module is used for determining the characteristic indexes of any preset node based on the calculated voltage values and the measured voltage values of the preset node before and after the fault and a preset characteristic index evaluation algorithm;
the preset characteristic index evaluation algorithm comprises the following steps:
Tt＝|(Utqc-Utfc)-(Utql-Utfl)|
wherein, TtIs a characteristic index of a preset node t, and t belongs to [1,2,3, …, n]N is the number of all preset nodes; u shapetqcAnd UtfcIndicating the calculated voltage value, U, of each of the preset nodes t before and after the faulttqlAnd UtflRepresenting the measured voltage values of the preset nodes t before and after the fault;
the fault positioning module is used for determining the preset node with the largest characteristic index and judging the branch where the fault occurs at the preset node with the largest characteristic index, and specifically comprises the following steps:
when the characteristic index T of the node m is presetmWhen the characteristic indexes of the nodes are larger than those of all other preset nodes, the following steps are carried out:
Tm/Tt＞1 t＝[1,2,3,...,n],t≠m
and judging that the fault occurs in the node branch where the preset node m is located.
8. An electronic device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, wherein the processor when executing the program performs the steps of the method for fault location of a power distribution network based on measured voltage difference as claimed in any one of claims 1 to 6.
9. A non-transitory computer-readable storage medium, having stored thereon a computer program, wherein the computer program, when being executed by a processor, is adapted to carry out the steps of the method for fault location of a power distribution network based on measured voltage difference values according to any of claims 1 to 6.
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