CN117233542B - Power distribution network single-phase earth fault section positioning method and system - Google Patents
Power distribution network single-phase earth fault section positioning method and system Download PDFInfo
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Abstract
The invention provides a method and a system for locating a single-phase earth fault section of a power distribution network, wherein the method comprises the following steps: when detecting a single-phase earth fault of a neutral point indirect grounding system, the master station selects a fault route and acquires fault wave recording information of the substation from near to far according to the fault route topology; judging whether the faults are positioned in the current substation section or not in sequence according to the fault wave recording information of the substation and the master station; and according to the fault wave recording information of the substation and the main station, calculating the current first peak value of the main station, the current first peak value of the substation, the fundamental wave amplitude of the zero sequence current of the main station, the fundamental wave amplitude of the zero sequence current of the substation and the waveform correlation of the zero sequence current of the main station respectively, and judging that the fault is positioned at the upstream of the current substation when the first peak value, the fundamental wave amplitude and the waveform correlation of the main station and the substation meet the preset conditions, otherwise, judging that the fault is positioned at the downstream of the current substation. According to the scheme, the positioning accuracy of the single-phase grounding fault section can be improved, and the single-phase grounding fault section is high in reliability and high in anti-interference performance.
Description
Technical Field
The invention belongs to the field of power fault detection, and particularly relates to a method and a system for locating a single-phase earth fault section of a power distribution network.
Background
Most of 10kV power distribution networks adopt a neutral point indirect grounding mode, and the proportion of single-phase grounding faults generated by a neutral point indirect grounding system in the total faults exceeds 80%. The single-phase earth fault of the power distribution network can bring about fire, electric shock and other safety accidents and large-area power failure risks, so that rapid processing of the single-phase earth fault of the power distribution network is more and more important, and section positioning of the single-phase earth fault of the power distribution network is of great significance for precisely isolating the fault and reducing power failure loss.
Currently, a single-phase earth fault processing device of a power distribution network is provided with an earth line selection device in a transformer substation and a power distribution network automation terminal outside the transformer substation. The grounding line selection device in the transformer substation only has the function of selecting a grounding fault line and does not have the function of positioning a fault line section; although the distribution network automation terminal has a single-phase earth fault section positioning function, the distribution network automation terminal action information of the whole network is collected by the distribution network automation master station depending on the distribution network automation master station and remote communication with the distribution master station, and the single-phase earth fault section positioning accuracy is affected under the condition that any distribution terminal in the distribution network is misjudged or missed.
Disclosure of Invention
In view of the above, the embodiment of the invention provides a method and a system for locating a single-phase grounding fault section of a power distribution network, which are used for solving the problems that the existing single-phase grounding fault section is easily affected by a power distribution terminal and the locating accuracy is not high.
In a first aspect of the embodiment of the present invention, a method for locating a single-phase earth fault section of a power distribution network is provided, including:
when detecting a single-phase earth fault of a neutral point indirect grounding system, the master station selects a fault route and acquires fault wave recording information of the substation from near to far according to the fault route topology;
judging whether the fault is positioned in the current substation section or not according to the fault wave recording information of the substation and the fault wave recording information of the master station;
according to fault wave recording information of the substation and the main station, respectively calculating a main station current first peak value, a substation current first peak value, a main station zero sequence current fundamental wave amplitude, a substation zero sequence current fundamental wave amplitude and waveform correlation of the main station zero sequence current and the substation zero sequence current;
when the waveform correlation of the primary station current first peak value, the secondary station current first peak value, the primary station zero-sequence current fundamental wave amplitude, the secondary station zero-sequence current fundamental wave amplitude and the primary station zero-sequence current and secondary station zero-sequence current meets the preset conditions, judging that the fault is positioned at the upstream of the current secondary station, and when the preset conditions are not met, judging that the fault is positioned at the downstream of the current secondary station;
wherein, the current head peak value of the substation is delta I Sub-peak I and the current head peak value I delta I of the main station Major peak I comparing the zero sequence current fundamental wave amplitude I of the substation Sub-peak Fundamental wave amplitude I of zero sequence current of main station Major peak Comparing the zero sequence current waveform correlation sigma of the master station and the slave station Son Comparing with a predetermined value, it is determined that the fault is located upstream of the first substation when the following condition is satisfied:
s|△I major peak |<|△I Sub-peak |<t/>|△I Major peak |；
sI Major peak <I Sub-peak <t/>I Major peak ；
|σ Son |>Q；
In the formula, s, t and Q are threshold values set according to actual requirements.
In a second aspect of the embodiment of the present invention, there is provided a single-phase earth fault section positioning system for a power distribution network, including:
the wave recording information acquisition module is used for acquiring fault wave recording information of the substation from near to far according to fault line topology after the main station selects a fault route when detecting single-phase earth fault of the neutral point indirect grounding system, and acquiring the fault wave recording information of the main station;
the fault section positioning module is used for sequentially judging whether the fault is positioned in the current substation section according to the fault wave recording information of the substation and the fault wave recording information of the master station;
according to fault wave recording information of the substation and the main station, respectively calculating a main station current first peak value, a substation current first peak value, a main station zero sequence current fundamental wave amplitude, a substation zero sequence current fundamental wave amplitude and waveform correlation of the main station zero sequence current and the substation zero sequence current;
when the waveform correlation of the primary station current first peak value, the secondary station current first peak value, the primary station zero-sequence current fundamental wave amplitude, the secondary station zero-sequence current fundamental wave amplitude and the primary station zero-sequence current and secondary station zero-sequence current meets the preset conditions, judging that the fault is positioned at the upstream of the current secondary station, and when the preset conditions are not met, judging that the fault is positioned at the downstream of the current secondary station;
wherein, the current head peak value of the substation is delta I Sub-peak I and the current head peak value I delta I of the main station Major peak I comparing the zero sequence current fundamental wave amplitude I of the substation Sub-peak Fundamental wave amplitude I of zero sequence current of main station Major peak Comparing the zero sequence current waveform correlation sigma of the master station and the slave station Son Comparing with a predetermined value, it is determined that the fault is located upstream of the first substation when the following condition is satisfied:
s|△I major peak |<|△I Sub-peak |<t/>|△I Major peak |；
sI Major peak <I Sub-peak <t/>I Major peak ；
|σ Son |>Q；
In the formula, s, t and Q are threshold values set according to actual requirements.
In a third aspect of the embodiments of the present invention, there is provided an electronic device comprising a memory, a processor and a computer program stored in the memory and executable on the processor, the processor implementing the steps of the method according to the first aspect of the embodiments of the present invention when the computer program is executed by the processor.
In a fourth aspect of the embodiments of the present invention, there is provided a computer readable storage medium storing a computer program which, when executed by a processor, implements the steps of the method provided by the first aspect of the embodiments of the present invention.
In the embodiment of the invention, the fault wave recording information of the sub-station is acquired step by step from near to far according to the fault line electrical topology, and the fault wave recording information of the main station is combined, so that the accurate fault section positioning can be realized, the communication reliability is high, and the influence of the non-fault line sub-station is avoided. Meanwhile, the master station and the substation can adopt uniform starting fixed values and starting criteria, failure detection sensitivity is not accompanied, the current peak value is subjected to variable quantity processing, unbalanced current and sampling zero drift values before failure can be filtered, and the system has strong anti-interference performance.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following description will briefly explain the drawings used in the embodiments or the description of the prior art, and it is obvious that the drawings described below are only some embodiments of the present invention, and other drawings may be obtained according to these drawings without inventive effort to a person skilled in the art.
Fig. 1 is a schematic structural diagram of a neutral point indirect grounding system according to an embodiment of the present invention;
fig. 2 is a schematic flow chart of a method for locating a single-phase earth fault section of a power distribution network according to an embodiment of the present invention;
FIG. 3 is a schematic structural diagram of a single-phase earth fault section positioning system for a power distribution network according to an embodiment of the present invention;
fig. 4 is a schematic structural diagram of an electronic device according to an embodiment of the present invention.
Detailed Description
In order to make the objects, features and advantages of the present invention more comprehensible, the technical solutions in the embodiments of the present invention are described in detail below with reference to the accompanying drawings, and it is apparent that the embodiments described below are only some embodiments of the present invention, but not all embodiments of the present invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
It should be understood that the term "comprising" and other similar meaning in the description of the invention or the claims and the above-mentioned figures is intended to cover a non-exclusive inclusion, such as a process, method or system, apparatus comprising a series of steps or elements, without limitation to the listed steps or elements. Furthermore, "first" and "second" are used to distinguish between different objects and are not used to describe a particular order.
It should be noted that, as shown in fig. 1, a neutral point indirect grounding system of a power distribution network is formed by a main station in a substation and a substation (such as a substation A, B, C, D, E, F) outside the substation. The master station can be a low-current grounding line selection device or an independent system master station deployed in the station. The substation is typically deployed at a sectionalizer and a tie switch of a distribution line, and may be a distribution automation terminal (FTU or DTU) or a dedicated terminal device.
When a single-phase earth fault occurs in the system, the master station firstly completes a fault line selection function and a fault wave recording function; the substation is provided with the same wave recording starting criterion as the master station, can record 3 cycles before starting at each sectional switch, and 1 week after starting, and is used for assisting the fault location of the master station by the analog quantity data of the zero sequence voltage and the zero sequence current of 4 cycles. Wherein, the fault record sampling rate of the system is not lower than 4000 point/s.
After the main station device finishes fault line selection, calling the fault wave recording information of the substation step by step from near to far according to the fault line topology. Judging the section fault of the substation after completing the information calling of one substation, stopping the information calling of the substation and outputting the positioning result of the fault section when the fault is positioned in the section; otherwise, calling the fault information of the next adjacent substation. And if all substation information calling and fault section research on the fault line are finished and fault section positioning is not finished, reporting the fault of the distribution line end.
Referring to fig. 2, a flow chart of a method for locating a single-phase earth fault section of a power distribution network according to an embodiment of the present invention includes:
s201, when detecting a single-phase earth fault of a neutral point indirect grounding system, a master station selects a fault route and acquires fault wave recording information of a substation from near to far according to fault route topology;
the master station is positioned in the power distribution station, and can realize a fault line selection function and a fault wave recording function after a single-phase earth fault occurs. The substation is located outside the power distribution station, can record fault waves when single-phase earth faults occur, and can upload fault wave recording information according to the main station instructions.
The fault wave recording information at least comprises zero sequence current sampling information.
S202, judging whether the fault is located in the current substation section or not according to the fault wave recording information of the substation and the fault wave recording information of the master station;
and sequentially acquiring fault wave recording information of the substation according to the distance between the substation and the main station, judging whether the fault is positioned in the current substation section by combining the fault wave recording information of the main station, if so, stopping acquiring the fault wave recording information of the substation, otherwise, continuously acquiring the fault wave recording information of the next substation.
According to fault wave recording information of the substation and the main station, respectively calculating a main station current first peak value, a substation current first peak value, a main station zero sequence current fundamental wave amplitude, a substation zero sequence current fundamental wave amplitude and waveform correlation of the main station zero sequence current and the substation zero sequence current;
when the waveform correlation of the primary station current first peak value, the secondary station current first peak value, the primary station zero-sequence current fundamental wave amplitude, the secondary station zero-sequence current fundamental wave amplitude and the primary station zero-sequence current and the secondary station zero-sequence current meets the preset condition, the fault is judged to be located at the upstream of the current secondary station, and when the preset condition is not met, the fault is judged to be located at the downstream of the current secondary station.
Specifically, the primary station current first peak value and the secondary station current first peak value calculation process comprises the following steps:
when the absolute value of the change amount of n continuous sampling points in the main station or the substation is smaller than the absolute value of the change amount of a first sampling point, and the absolute value of the change amount of the first sampling point is larger than K times of the absolute value of the change amount of n to 2n sampling points before the first sampling point, the absolute value of the first sampling point is larger than the absolute value of the change amount of n sampling points after the first sampling point, the current value corresponding to the first sampling point is taken as a current head peak value;
the variation of the sampling point is the absolute value of the current sampling point value minus the sampling point value before a power frequency period, n and K are adjustable threshold values, the value of n can be in the range of [5,20] and the value of K can be in the range of [2,10], and the variation of the sampling point can be generally set according to actual application scenes or requirements.
Exemplary, the absolute value of the current head peak value variation of the n zero sequence current of the main station line and the fault record of the substation A is extracted Major peak |、|△I Sub A peak I, when a certain current is sampled to value I k And (k is a sampling sequence number) judging as a fault current first peak value when all the following conditions are met:
the absolute value of the change amount of the continuous 6 sampling points in front of any sampling point in the master station or the substation is smaller than that of the change amount of the sampling point: i delta I k |>max{|△I k-1 |，|△I k-2 |，|△I k-3 |，|△I k-4 |，|△I k-5 |，|△I k-6 The sampling point variation is the sampling value of the sampling point value minus the sampling value before a power frequency period (such as 20 ms): i.e. DeltaI k =△I k -△I k-N Setting N points in each power frequency period;
the absolute value of the variation of the sampling point is 5 times larger than that of the previous 7 th to 12 th sampling points, namely the absolute value of the variation of the sampling point is delta I k |>5max{|△I k-7 |，|△I k-8 |，|△I k-9 |，|△I k-10 |，|△I k-11 |，|△I k-12 |}；
The absolute value of the variation of the sampling point is larger than that of the variation of 6 continuous sampling points, namely the delta I k |>max{|△I k+1 |，|△I k+2 |，|△I k+3 |，|△I k+4 |，|△I k+5 |，|△I k+6 |}。
Specifically, according to the current first peak value of the master station and the substation and the sampling data window of the power frequency period after the current first peak value, calculating the fundamental wave amplitude of the zero-sequence current of the master station and the fundamental wave amplitude of the zero-sequence current of the substation, and calculating the waveform correlation of the zero-sequence current of the master station and the zero-sequence current of the substation:
；
wherein,the method is characterized in that the method is used for representing waveform correlation, N represents the length of a data window, and the value is the sampling point number of one power frequency period,/for the sampling point number of one power frequency period>Zero sequence current representing the ith sampling point in the master time window,/and>zero sequence current representing the ith sampling point in the substation time window, +.>Represents the average value of the zero sequence current of the sampling point of the main station, +.>Representing the average value of the sub-station sampling point zero sequence current.
In one embodiment, the substation current head peaks |ΔI are respectively calculated Sub-peak I and the current head peak value I delta I of the main station Major peak I comparing the zero sequence current fundamental wave amplitude I of the substation Sub-peak Fundamental wave amplitude I of zero sequence current of main station Major peak Comparing the zero sequence current waveform correlation sigma of the master station and the slave station Son Comparing with a predetermined value, it is determined that the fault is located upstream of the first substation when the following condition is satisfied:
s|△I major peak |<|△I Sub-peak |<t/>|△I Major peak |；
sI Major peak <I Sub-peak <t/>I Major peak ；
|σ Son |>Q；
Wherein s, t and Q are threshold values set according to actual requirements, the value range of s is [0.7,0.95], the value range of t is [1.05,1.3], and the value range of Q is [0.8,0.95].
Specifically, when the primary station current first peak value, the first substation current first peak value, the primary station zero-sequence current fundamental wave amplitude, the first substation zero-sequence current fundamental wave amplitude and the waveform correlation of the primary station zero-sequence current and the first substation zero-sequence current meet the preset conditions, determining that the fault is located between the transformer substation and the first substation;
otherwise, judging whether the second sub-station downstream of the first sub-station meets the preset condition, if so, judging that the fault is positioned between the first sub-station and the second sub-station, and if not, continuously judging whether the third sub-station downstream of the second sub-station meets the preset condition until the fault section is positioned on the current fault route.
Illustratively, as in the substation of FIG. 1, if the fault point is determined to be upstream of substation A, locating the fault point in substation-substation A section; if the fault point is judged to be upstream of the sub-station B and the sub-station E, the fault point is positioned in the sub-station A-sub-station B/E section, if the fault point is judged to be downstream of the sub-station B, the sub-station C downstream of the sub-station B is continuously judged, and if the fault point is judged to be downstream of the sub-station E, the sub-station F downstream of the sub-station E is continuously judged. The faulty section is thus searched sequentially until the end of the line.
If the fault section has not been located by the last substation, then a distribution line end fault may be determined.
In the embodiment, based on fault wave recording of the master station and the substation, fault section positioning is performed by acquiring fault wave recording information of the substation step by step after fault line selection, so that the fault positioning accuracy can be improved, and the section positioning is performed by adopting fault information of all nodes in the fault line station and outside the station, so that higher line selection accuracy can be achieved; the master station only gathers fault information of each substation of the fault line to conduct fault section research and judgment, and fault positioning accuracy is not affected by non-fault line substations; the master station and the substations of the fault line are communicated step by step from near to far according to the line electrical topology, so that communication congestion is avoided, and the system communication reliability is high; the master station and the substation adopt unified starting fixed values and starting criteria, and the situation that the fault detection sensitivity is not accompanied is avoided; the absolute values of the current first peak value variation and the current waveform correlation coefficient in the criterion are not influenced by the installation and the access polarity of the sectionalized switch CT; the first peak value of the current in the criterion is processed by the variable quantity, unbalanced current and sampling zero drift value before failure can be filtered, and the anti-interference performance is high.
It should be understood that the sequence number of each step in the above embodiment does not mean the sequence of execution, and the execution sequence of each process should be determined by its function and internal logic, and should not be construed as limiting the implementation process of the embodiment of the present invention.
Fig. 3 is a schematic structural diagram of a single-phase earth fault section positioning system of a power distribution network according to an embodiment of the present invention, where the system includes:
the wave recording information obtaining module 310 is configured to obtain fault wave recording information of the substation from near to far according to the fault line topology after the main station selects a fault route when detecting a single-phase earth fault of the neutral point indirect earth system, and obtain fault wave recording information of the main station;
the fault section positioning module 320 is configured to sequentially determine whether the fault is located in the current substation section according to the fault record information of the substation and the fault record information of the master station;
according to fault wave recording information of the substation and the main station, respectively calculating a main station current first peak value, a substation current first peak value, a main station zero sequence current fundamental wave amplitude, a substation zero sequence current fundamental wave amplitude and waveform correlation of the main station zero sequence current and the substation zero sequence current;
when the waveform correlation of the primary station current first peak value, the secondary station current first peak value, the primary station zero-sequence current fundamental wave amplitude, the secondary station zero-sequence current fundamental wave amplitude and the primary station zero-sequence current and secondary station zero-sequence current meets the preset condition, the fault is judged to be positioned at the upstream of the current secondary station, and when the preset condition is not met, the fault is judged to be positioned at the downstream of the current secondary station.
Specifically, when the absolute value of the variation of n continuous sampling points in the master station or the substation is smaller than the absolute value of the variation of a first sampling point, and the absolute value of the variation of the first sampling point is larger than K times of the absolute value of the variation of n-2n sampling points before the first sampling point, the absolute value of the first sampling point is larger than the absolute value of the variation of n sampling points after the first sampling point, the current value corresponding to the first sampling point is taken as a current head peak value;
the sampling point variation is the absolute value of the current sampling point value minus the sampling point value before one power frequency period, and n and K are adjustable threshold values.
Specifically, according to the current first peak value of the master station and the substation and the sampling data window of the power frequency period after the current first peak value, calculating the fundamental wave amplitude of the zero-sequence current of the master station and the fundamental wave amplitude of the zero-sequence current of the substation, and calculating the waveform correlation of the zero-sequence current of the master station and the zero-sequence current of the substation:
；
wherein,the method is characterized in that the method is used for representing waveform correlation, N represents the length of a data window, and the value is the sampling point number of one power frequency period,/for the sampling point number of one power frequency period>Zero sequence current representing the i-th sampling point of the master station,/->Zero sequence current representing the ith sampling point of the substation,/->Represents the average value of the zero sequence current of the sampling point of the main station, +.>Representing the average value of the sub-station sampling point zero sequence current.
Specifically, the current head peak value of the substation is delta I Sub-peak I and the current head peak value I delta I of the main station Major peak I comparing the zero sequence current fundamental wave amplitude I of the substation Sub-peak Fundamental wave amplitude I of zero sequence current of main station Major peak Comparing the zero sequence current waveform correlation sigma of the master station and the slave station Son Comparing with a predetermined value, determining that the following condition is satisfiedThe fault is located upstream of the first substation:
s|△I major peak |<|△I Sub-peak |<t/>|△I Major peak |；
sI Major peak <I Sub-peak <t/>I Major peak ；
|σ Son |>Q；
In the formula, s, t and Q are threshold values set according to actual requirements.
Optionally, when the primary station current first peak value, the first substation current first peak value, the primary station zero-sequence current fundamental wave amplitude, the first substation zero-sequence current fundamental wave amplitude and the waveform correlation of the primary station zero-sequence current and the first substation zero-sequence current meet the preset conditions, determining that the fault is located between the transformer substation and the first substation;
otherwise, judging whether the second sub-station downstream of the first sub-station meets the preset condition, if so, judging that the fault is positioned between the first sub-station and the second sub-station, and if not, continuously judging whether the third sub-station downstream of the second sub-station meets the preset condition until the fault section is positioned on the current fault route.
It will be clearly understood by those skilled in the art that, for convenience and brevity of description, the specific working process of the above-described system and module may refer to the corresponding process in the foregoing method embodiment, which is not repeated herein.
Fig. 4 is a schematic structural diagram of an electronic device according to an embodiment of the present invention. The electronic equipment is used for locating a single-phase grounding fault section of the power distribution network. As shown in fig. 4, the electronic apparatus 4 of this embodiment includes: memory 410, processor 420, and system bus 430, wherein memory 410 includes an executable program 4101 stored thereon, and those skilled in the art will appreciate that the electronic device structure shown in fig. 4 is not limiting of electronic devices and may include more or fewer components than shown, or may combine certain components, or a different arrangement of components.
The following describes the respective constituent elements of the electronic device in detail with reference to fig. 4:
the memory 410 may be used to store software programs and modules, and the processor 420 may execute various functional applications and data processing of the electronic device by executing the software programs and modules stored in the memory 410. The memory 410 may mainly include a storage program area and a storage data area, wherein the storage program area may store an operating system, an application program (such as a sound playing function, an image playing function, etc.) required for at least one function, and the like; the storage data area may store data created according to the use of the electronic device (such as cache data), and the like. In addition, memory 410 may include high-speed random access memory, and may also include non-volatile memory, such as at least one magnetic disk storage device, flash memory device, or other volatile solid-state storage device.
An executable program 4101 containing network request methods on the memory 410, the executable program 4101 may be partitioned into one or more modules/units that are stored in the memory 410 and executed by the processor 420 to implement single phase earth fault zone localization, etc., the one or more modules/units may be a series of computer program instruction segments capable of performing specific functions describing the execution of the executable program 4101 in the electronic device 4. For example, the executable program 4101 may be divided into functional modules such as a recording information acquisition module and a fault section locating module.
The processor 420 is a control center of the electronic device, connects various parts of the entire electronic device using various interfaces and lines, and performs various functions of the electronic device and processes data by running or executing software programs and/or modules stored in the memory 410, and invoking data stored in the memory 410, thereby performing overall state monitoring of the electronic device. Optionally, the processor 420 may include one or more processing units; preferably, the processor 420 may integrate an application processor that primarily handles operating systems, applications, etc., with a modem processor that primarily handles wireless communications. It will be appreciated that the modem processor described above may not be integrated into the processor 320.
The system bus 430 is used to connect various functional units inside the computer, and CAN transfer data information, address information, and control information, and its kind may be, for example, a PCI bus, an ISA bus, a CAN bus, and the like. Instructions from the processor 420 are transferred to the memory 410 via the bus, the memory 410 feeds back data to the processor 420, and the system bus 430 is responsible for data and instruction interaction between the processor 420 and the memory 410. Of course, the system bus 430 may also access other devices, such as a network interface, a display device, etc.
In an embodiment of the present invention, the executable program executed by the processor 420 included in the electronic device includes:
when detecting a single-phase earth fault of a neutral point indirect grounding system, the master station selects a fault route and acquires fault wave recording information of the substation from near to far according to the fault route topology;
judging whether the fault is positioned in the current substation section or not according to the fault wave recording information of the substation and the fault wave recording information of the master station;
according to fault wave recording information of the substation and the main station, respectively calculating a main station current first peak value, a substation current first peak value, a main station zero sequence current fundamental wave amplitude, a substation zero sequence current fundamental wave amplitude and waveform correlation of the main station zero sequence current and the substation zero sequence current;
when the waveform correlation of the primary station current first peak value, the secondary station current first peak value, the primary station zero-sequence current fundamental wave amplitude, the secondary station zero-sequence current fundamental wave amplitude and the primary station zero-sequence current and the secondary station zero-sequence current meets the preset condition, the fault is judged to be located at the upstream of the current secondary station, and when the preset condition is not met, the fault is judged to be located at the downstream of the current secondary station.
It will be clearly understood by those skilled in the art that, for convenience and brevity of description, specific working procedures of the above-described system, apparatus and module may refer to corresponding procedures in the foregoing method embodiments, which are not repeated herein.
In the foregoing embodiments, the descriptions of the embodiments are emphasized, and in part, not described or illustrated in any particular embodiment, reference is made to the related descriptions of other embodiments.
The above embodiments are only for illustrating the technical solution of the present invention, and not for limiting the same; although the 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 scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention.
Claims (9)
1. A method for locating a single-phase earth fault section of a power distribution network, comprising the steps of:
when detecting a single-phase earth fault of a neutral point indirect grounding system, the master station selects a fault route and acquires fault wave recording information of the substation from near to far according to the fault route topology;
judging whether the fault is positioned in the current substation section or not according to the fault wave recording information of the substation and the fault wave recording information of the master station;
according to fault wave recording information of the substation and the main station, respectively calculating a main station current first peak value, a substation current first peak value, a main station zero sequence current fundamental wave amplitude, a substation zero sequence current fundamental wave amplitude and waveform correlation of the main station zero sequence current and the substation zero sequence current;
when the waveform correlation of the primary station current first peak value, the secondary station current first peak value, the primary station zero-sequence current fundamental wave amplitude, the secondary station zero-sequence current fundamental wave amplitude and the primary station zero-sequence current and secondary station zero-sequence current meets the preset conditions, judging that the fault is positioned at the upstream of the current secondary station, and when the preset conditions are not met, judging that the fault is positioned at the downstream of the current secondary station;
wherein, the current head peak value of the substation is delta I Sub-peak I and the current head peak value I delta I of the main station Major peak I comparing the zero sequence current fundamental wave amplitude I of the substation Sub-peak Fundamental wave amplitude I of zero sequence current of main station Major peak Comparing the zero sequence current waveform correlation sigma of the master station and the slave station Son Comparing with a predetermined value, it is determined that the fault is located upstream of the current substation when the following condition is satisfied:
s|△I major peak |<|△I Sub-peak |<t/>|△I Major peak |；
sI Major peak <I Sub-peak <t/>I Major peak ；
|σ Son |>Q；
In the formula, s, t and Q are threshold values set according to actual requirements.
2. The method of claim 1, wherein calculating the waveform correlation of the master station current first peak value, the substation current first peak value, the master station zero sequence current fundamental amplitude, the substation zero sequence current fundamental amplitude, and the master station zero sequence current and the substation zero sequence current, respectively, comprises:
when the absolute value of the variation of n continuous sampling points in the main station or the substation is smaller than the absolute value of the variation of the first sampling point, the absolute value of the variation of the first sampling point is larger than K times of the absolute value of the variation of n sampling points before the first sampling point and the absolute value of the first sampling point is larger than the absolute value of the variation of n sampling points after the first sampling point, the current value corresponding to the first sampling point is taken as a current head peak value;
the sampling point variation is the absolute value of the current sampling point value minus the sampling point value before one power frequency period, and n and K are adjustable threshold values.
3. The method of claim 1, wherein calculating the waveform correlation of the master station current first peak value, the substation current first peak value, the master station zero sequence current fundamental amplitude, the substation zero sequence current fundamental amplitude, and the master station zero sequence current and the substation zero sequence current, respectively, comprises:
according to the current first peak value of the master station and the substation and the sampling data window of the power frequency period after the current first peak value, calculating the fundamental wave amplitude of the zero sequence current of the master station and the fundamental wave amplitude of the zero sequence current of the substation, and calculating the waveform correlation of the zero sequence current of the master station and the zero sequence current of the substation:
；
wherein,representing waveform correlation, N represents data window length, sampling point number of one power frequency period is taken, and +.>Zero sequence current representing the ith sampling point in the master time window,/and>zero sequence current representing the ith sampling point in the substation time window, +.>Represents the average value of the zero sequence current of the sampling point of the main station, +.>Representing the average value of the sub-station sampling point zero sequence current.
4. The method of claim 1, wherein determining that the fault is upstream of the current substation when the primary station current first peak value, the secondary station current first peak value, the primary station zero sequence current fundamental wave amplitude, the secondary station zero sequence current fundamental wave amplitude, and the waveform correlation of the primary station zero sequence current and the secondary station zero sequence current satisfy predetermined conditions, and determining that the fault is downstream of the current substation when the predetermined conditions are not satisfied further comprises:
when the waveform correlation of the primary station current first peak value, the first substation current first peak value, the primary station zero-sequence current fundamental wave amplitude, the first substation zero-sequence current fundamental wave amplitude and the primary station zero-sequence current and the first substation zero-sequence current meets the preset condition, judging that the fault is located between the transformer substation and the first substation;
otherwise, judging whether a second sub-station downstream of the first sub-station meets the preset condition, if so, judging that the fault is positioned between the first sub-station and the second sub-station, and if not, continuously judging whether a third sub-station downstream of the second sub-station meets the preset condition until the fault section is positioned on the current fault route;
the master station is located in the transformer substation, and the first substation is the substation closest to the transformer substation.
5. A single-phase earth fault section location system for a power distribution network, comprising:
the wave recording information acquisition module is used for acquiring fault wave recording information of the substation from near to far according to fault line topology after the main station selects a fault route when detecting single-phase earth fault of the neutral point indirect grounding system, and acquiring the fault wave recording information of the main station;
the fault section positioning module is used for sequentially judging whether the fault is positioned in the current substation section according to the fault wave recording information of the substation and the fault wave recording information of the master station;
according to fault wave recording information of the substation and the main station, respectively calculating a main station current first peak value, a substation current first peak value, a main station zero sequence current fundamental wave amplitude, a substation zero sequence current fundamental wave amplitude and waveform correlation of the main station zero sequence current and the substation zero sequence current;
when the waveform correlation of the primary station current first peak value, the secondary station current first peak value, the primary station zero-sequence current fundamental wave amplitude, the secondary station zero-sequence current fundamental wave amplitude and the primary station zero-sequence current and secondary station zero-sequence current meets the preset conditions, judging that the fault is positioned at the upstream of the current secondary station, and when the preset conditions are not met, judging that the fault is positioned at the downstream of the current secondary station;
wherein, the current head peak value of the substation is delta I Sub-peak I and the current head peak value I delta I of the main station Major peak I comparing the zero sequence current fundamental wave amplitude I of the substation Sub-peak Fundamental wave amplitude I of zero sequence current of main station Major peak Comparing the zero sequence current waveform correlation sigma of the master station and the slave station Son Comparing with a predetermined value, it is determined that the fault is located upstream of the current substation when the following condition is satisfied:
s|△I major peak |<|△I Sub-peak |<t/>|△I Major peak |；
sI Major peak <I Sub-peak <t/>I Major peak ；
|σ Son |>Q；
In the formula, s, t and Q are threshold values set according to actual requirements.
6. The system of claim 5, wherein the calculating of the waveform correlation of the primary station current first peak value, the secondary station current first peak value, the primary station zero sequence current fundamental amplitude, the secondary station zero sequence current fundamental amplitude, and the primary station zero sequence current and the secondary station zero sequence current, respectively, comprises:
when the absolute value of the change amount of n continuous sampling points in the main station or the substation is smaller than the absolute value of the change amount of a first sampling point, and the absolute value of the change amount of the first sampling point is larger than K times of the absolute value of the change amount of n to 2n sampling points before the first sampling point, the absolute value of the first sampling point is larger than the absolute value of the change amount of n sampling points after the first sampling point, the current value corresponding to the first sampling point is taken as a current head peak value;
the sampling point variation is the absolute value of the current sampling point value minus the sampling point value before one power frequency period, and n and K are adjustable threshold values.
7. The system of claim 5, wherein the calculating of the waveform correlation of the primary station current first peak value, the secondary station current first peak value, the primary station zero sequence current fundamental amplitude, the secondary station zero sequence current fundamental amplitude, and the primary station zero sequence current and the secondary station zero sequence current, respectively, comprises:
according to the current first peak value of the master station and the substation and the sampling data window of the power frequency period after the current first peak value, calculating the fundamental wave amplitude of the zero sequence current of the master station and the fundamental wave amplitude of the zero sequence current of the substation, and calculating the waveform correlation of the zero sequence current of the master station and the zero sequence current of the substation:
；
wherein,representing waveform correlation, N represents data window length, sampling point number of one power frequency period is taken, and +.>Zero sequence current representing the ith sampling point in the master time window,/and>zero sequence current representing the ith sampling point in the substation time window, +.>Represents the average value of the zero sequence current of the sampling point of the main station, +.>Representing the average value of the sub-station sampling point zero sequence current.
8. An electronic device comprising a memory, a processor and a computer program stored in the memory and executable on the processor, wherein the processor, when executing the computer program, implements the steps of a method for locating single phase earth fault sections of a power distribution network as claimed in any one of claims 1 to 4.
9. A computer readable storage medium storing a computer program, wherein the computer program when executed implements the steps of a method for locating single phase earth fault sections of a power distribution network according to any one of claims 1 to 4.
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