CN113295966A

CN113295966A - Early failure type identification method and device

Info

Publication number: CN113295966A
Application number: CN202110572570.8A
Authority: CN
Inventors: 张文海; 楚恬歆; 陈琳; 韦凌霄; 刘庆时; 张宏宇; 席嫣娜; 瞿科; 肖先勇
Original assignee: Sichuan University; State Grid Beijing Electric Power Co Ltd
Current assignee: Sichuan University; State Grid Beijing Electric Power Co Ltd
Priority date: 2021-05-25
Filing date: 2021-05-25
Publication date: 2021-08-24
Anticipated expiration: 2041-05-25
Also published as: CN113295966B

Abstract

The invention discloses a method and a device for identifying early fault types, wherein the method comprises the following steps: collecting disturbance waveform data of a disturbance event; judging whether the early fault disturbance duration is within the early fault time range, if so, judging whether the fault initial phase angle of the voltage is within the margin range of the voltage peak value; when judging whether the initial fault phase angle of the voltage is within the margin range of the voltage peak value, if so, judging whether the load current variation is less than or equal to a set current threshold value; when judging whether the load current variation is smaller than or equal to a set current threshold value, if so, executing a first group of criteria, and if not, executing a second group of criteria; the early failure type of the disturbance event is identified based on either the first set of criteria or the second set of criteria. The invention solves the technical problem of how to identify the single-phase grounding type early fault and the different-name phase two-point grounding type early fault in the low-current grounding system.

Description

Early failure type identification method and device

Technical Field

The invention relates to the technical field of power distribution network faults, in particular to an early fault type identification method and device.

Background

The early fault is an intermittent and transient fault which occurs before a permanent fault of equipment, has the characteristic of short duration, cannot cause the action of a relay protection device in a fault disturbance mode, and can repeatedly occur within a period of time and finally cause the permanent fault. Due to the operational characteristics of low current grounding systems, early faults occurring in such systems may appear as "single-phase grounding" and "heteronymous two-point grounding". Wherein, the early fault of the different-name phase two-point grounding type can occur on the same feeder line or different feeder lines.

At present, the research on early faults of a distribution line is mainly directed at an effective grounding system, a medium-voltage distribution network in China mainly adopts low-current grounding, the early faults in the system can be represented as a single-phase grounding type and a different-name phase two-point grounding type, and a small amount of research on the early faults of the low-current grounding system does not carry out system analysis on the expression mode and waveform characteristics of the early faults in the system.

An effective solution is not provided at present aiming at the problem of how to identify the single-phase grounding type early fault and the different-name phase two-point grounding type early fault in the low-current grounding system.

Disclosure of Invention

In view of the above-mentioned deficiencies in the prior art, the present invention provides a method and an apparatus for identifying an early fault type, so as to at least solve the technical problem of how to identify a single-phase grounding type early fault and a different-name phase two-point grounding type early fault in a low-current grounding system.

According to an aspect of the embodiments of the present invention, there is provided a method for identifying an early failure type, including: acquiring disturbance waveform data of a disturbance event, wherein the disturbance waveform data at least comprises: the disturbance duration of early fault, the initial fault phase angle of voltage and the load current variation; judging whether the early fault disturbance duration is within an early fault time range, if so, judging whether a fault initial phase angle of the voltage is within a margin range of a voltage peak value, and if not, continuously acquiring the disturbance waveform data of the disturbance event; when judging whether the initial fault phase angle of the voltage is in the margin range of the voltage peak value, if so, judging whether the load current variation is less than or equal to a set current threshold value, and if not, continuously acquiring the disturbance waveform data of the disturbance event; when judging whether the load current variation is smaller than or equal to a set current threshold value, if so, executing a first group of criteria, and if not, executing a second group of criteria; identifying an early failure type of the disturbance event based on the first set of criteria or the second set of criteria.

Optionally, the early failure time range is [5ms, 80ms ].

Optionally, the margin range of the voltage peak value is

Where k is a natural number and ε is the voltage peak margin.

Optionally, the set current threshold is σ₁I_N，σ₁＝5％，σ₁Is a first scale factor, I_NIs the nominal phase current of the line.

Optionally, performing the first set of criteria comprises: judging whether the half-wave effective value of the current of one phase is greater than mu I_NIf yes, judging whether the effective value of the zero sequence voltage of the first cycle before the disturbance starting moment and the zero sequence voltage of the first cycle after the disturbance ending moment are both larger than or equal to beta₁V_NAnd whether the effective value of the zero sequence current of the first cycle before the disturbance starting moment and the zero sequence current of the first cycle after the disturbance ending moment are both greater than or equal to beta₂I_NIf not, judging whether the effective value of the zero sequence voltage of the first cycle before the disturbance starting moment and the zero sequence voltage of the first cycle after the disturbance ending moment are both smaller than beta₁V_NAnd whether the effective value of the zero sequence current of the first cycle before the disturbance starting moment and the zero sequence current of the first cycle after the disturbance ending moment are both less than beta₂I_NWhere μ is the proportionality coefficient of the phase current, I_NIs the rated phase current of the line; judging whether the zero sequence voltage effective value of the first cycle before the disturbance starting moment and the zero sequence voltage of the first cycle after the disturbance ending moment are both greater than or equal to beta₁V_NAnd whether the effective value of the zero sequence current of the first cycle before the disturbance starting moment and the zero sequence current of the first cycle after the disturbance ending moment are both greater than or equal to beta₂I_NIf yes, judging whether the effective value of the zero sequence voltage of the first cycle before the disturbance starting moment and the zero sequence voltage of the first cycle after the disturbance ending moment meet a first voltage difference inequality, and whether the effective value of the zero sequence current of the first cycle before the disturbance starting moment and the zero sequence current of the first cycle after the disturbance ending moment meet a first current difference inequality, if not, continuously acquiring disturbance waveform data of the disturbance event, wherein beta is beta₁Is a first scale parameter, beta₂Is a first scale parameter, V_NIs the rated phase voltage of the line; when judging whether the effective value of the zero-sequence voltage of the first cycle before the disturbance starting moment and the zero-sequence voltage of the first cycle after the disturbance terminating moment meet a first voltage difference inequality, and whether the effective value of the zero-sequence current of the first cycle before the disturbance starting moment and the zero-sequence current of the first cycle after the disturbance terminating moment meet a first current difference inequality, if so, the early fault type of the disturbance event is a different-name-phase two-point grounding type early fault, and if not, the disturbance waveform data of the disturbance event is continuously acquired; at the moment of judging disturbanceWhether the effective value of the zero sequence voltage of the first cycle before the starting moment and the zero sequence voltage of the first cycle after the disturbance ending moment are both smaller than beta₁V_NAnd whether the effective value of the zero sequence current of the first cycle before the disturbance starting moment and the zero sequence current of the first cycle after the disturbance ending moment are both less than beta₂I_NIf yes, judging the effective value V of the full wave of the zero sequence voltage_0rmsWhether or not the maximum value of (b) is greater than lambdav_NIf not, continuing to acquire the disturbance waveform data of the disturbance event; after judging zero sequence voltage full wave effective value V_0rmsWhether or not the maximum value of (b) is greater than lambdav_NIf the single-phase grounding type early fault exists, the early fault type of the disturbance event is a single-phase grounding type early fault, and if the single-phase grounding type early fault does not exist, whether the half-wave effective value of the current of one phase is larger than mu I or not is continuously judged_NWherein, λ is a proportionality coefficient.

Optionally, the first voltage difference value inequality is: i V_0befo_re-V_0after|<σ₂V_NThe first current difference inequality is: i_0befo_re-I_0after|<σ₃V_NWherein V is_0beforeFor disturbing the zero-sequence voltage effective value, V, of the previous cycle at the start time_0afterZero sequence voltage of a cycle after the disturbance termination time, I_0beforeFor disturbing the zero-sequence current effective value of the previous cycle, I_0afterFor zero-sequence currents of a cycle after the termination of a disturbance₂Is the second proportionality coefficient, σ₃Is the third scaling factor.

Optionally, performing the second set of criteria comprises: judging whether the load current after the disturbance is reduced relative to the load current before the disturbance, if so, judging whether the half-wave effective value exceeding one-phase current is greater than mu I_NIf not, continuing to acquire the disturbance waveform data of the disturbance event; judging whether the half-wave effective value of the current exceeding one phase is greater than mu I_NIf yes, judging whether the effective value of the zero sequence voltage of the previous cycle at the disturbance starting moment is more than or equal to beta or not₁V_NAnd whether the zero sequence voltage of a cycle of wave after the disturbance termination moment is less than beta or not₁V_NAnd whether the effective value of the zero-sequence current of the first cycle wave before the disturbance starting moment is more than or equal to beta or not₂I_NAnd whether the zero sequence current of a cycle of wave after the disturbance termination moment is less than beta or not₂I_NIf not, continuing to acquire the disturbance waveform data of the disturbance event, wherein mu is a proportionality coefficient of rated phase current, and I_NIs the rated phase current of the line; judging whether the zero sequence voltage effective value of the previous cycle at the disturbance starting moment is more than or equal to beta₁V_NAnd whether the zero sequence voltage of a cycle of wave after the disturbance termination moment is less than beta or not₁V_NAnd whether the effective value of the zero-sequence current of the first cycle wave before the disturbance starting moment is more than or equal to beta or not₂I_NAnd whether the zero sequence current of a cycle of wave after the disturbance termination moment is less than beta or not₂I_NIf yes, judging whether the effective value of the zero sequence voltage of the first cycle before the disturbance starting moment and the zero sequence voltage of the first cycle after the disturbance ending moment meet a second voltage difference inequality, and whether the effective value of the zero sequence current of the first cycle before the disturbance starting moment and the zero sequence current of the first cycle after the disturbance ending moment meet a second current difference inequality, if not, continuously acquiring the disturbance waveform data of the disturbance event, wherein beta is beta₁Is a first scale parameter, beta₂Is a first scale parameter; and if the type of the early fault of the disturbance event is a different-name phase two-point grounding type early fault, if not, continuously acquiring the disturbance waveform data of the disturbance event.

Optionally, the second voltage difference value inequality is: i V_0befo_re-V_0after|≥σ₂V_NThe second current difference inequality is as follows: i_0befo_re-I_0after|≥σ₃V_NWherein V is_0befo_reTo be disturbedZero sequence voltage effective value, V, of the first cycle before the start time_0afterZero sequence voltage of a cycle after the disturbance termination time, I_0befo_reFor disturbing the zero-sequence current effective value of the previous cycle, I_0afterFor zero-sequence currents of a cycle after the termination of a disturbance₂Is the second proportionality coefficient, σ₃Is the third scaling factor.

According to another aspect of the embodiments of the present invention, there is also provided an early failure type identification apparatus, including: an acquisition module, configured to acquire disturbance waveform data of a disturbance event, where the disturbance waveform data at least includes: the disturbance duration of early fault, the initial fault phase angle of voltage and the load current variation; the first judgment module is used for judging whether the early fault disturbance duration is within an early fault time range, if so, judging whether a fault initial phase angle of the voltage is within a margin range of a voltage peak value, and if not, continuously acquiring the disturbance waveform data of the disturbance event; the second judgment module is used for judging whether the initial fault phase angle of the voltage is within the margin range of the voltage peak value, if so, judging whether the load current variation is smaller than or equal to a set current threshold value, and if not, continuously acquiring the disturbance waveform data of the disturbance event; the third judging module is used for executing the first group of criteria if the load current variation is judged to be less than or equal to the set current threshold, and executing the second group of criteria if the load current variation is not judged to be less than or equal to the set current threshold; an identification module configured to identify an early failure type of the disturbance event based on the first set of criteria or the second set of criteria.

According to another aspect of the embodiments of the present invention, there is also provided a computer-readable storage medium, where the computer-readable storage medium includes a stored program, where the program, when executed, controls an apparatus where the computer-readable storage medium is located to perform the method for identifying an early failure type described in any one of the above.

In the embodiment of the present invention, disturbance waveform data of a collected disturbance event is adopted, where the disturbance waveform data at least includes: the disturbance duration of early fault, the initial fault phase angle of voltage and the load current variation; judging whether the early fault disturbance duration is within the early fault time range, if so, judging whether the fault initial phase angle of the voltage is within the margin range of the voltage peak value, and if not, continuously acquiring disturbance waveform data of the disturbance event; when judging whether the initial fault phase angle of the voltage is in the margin range of the voltage peak value, if so, judging whether the load current variation is less than or equal to a set current threshold value, and if not, continuously acquiring disturbance waveform data of a disturbance event; when judging whether the load current variation is smaller than or equal to a set current threshold value, if so, executing a first group of criteria, and if not, executing a second group of criteria; according to the first group of criteria or the second group of criteria, the early fault type of the disturbance event is identified, the diversity of the expression forms of the early faults in the system is fully considered according to the operation characteristics of the low-current grounding system, and the early fault of the disturbance event is identified based on the composite criteria, so that the technical effect of accurately identifying the grounding type early fault of the low-current grounding system is achieved, and the technical problem of how to identify the single-phase grounding type early fault and the different-name phase two-point grounding type early fault in the low-current grounding system is solved.

Drawings

FIG. 1 is a flow chart of a method of identifying early failure types according to an embodiment of the invention;

FIG. 2(a) is a schematic of a three-phase voltage waveform in a single phase ground version according to an alternative embodiment of the present invention;

FIG. 2(b) is a schematic illustration of three-phase current waveforms in a single phase ground version according to an alternative embodiment of the present invention;

fig. 2(c) is a schematic diagram of a zero sequence voltage waveform in a single phase ground version according to an alternative embodiment of the invention;

fig. 2(d) is a schematic diagram of a zero sequence current waveform in a single phase ground type according to an alternative embodiment of the present invention;

fig. 3(a) is a schematic diagram of a three-phase voltage waveform for a same-feeder opposite-name phase two-point ground type according to an alternative embodiment of the present invention;

fig. 3(b) is a schematic diagram of a three-phase current waveform in a homonymous phase two-point ground type according to an alternative embodiment of the present invention;

fig. 3(c) is a schematic diagram of a zero sequence voltage waveform in a same feeder line different phase two-point grounding type according to an alternative embodiment of the present invention;

fig. 3(d) is a schematic diagram of a zero sequence current waveform when the same feeder line is different in name and two-point grounded according to an alternative embodiment of the present invention;

FIG. 4(a) is a schematic of a three-phase voltage waveform for different feeder alias phase two-point grounding types according to an alternative embodiment of the present invention;

FIG. 4(b) is a schematic diagram of the three-phase current waveforms of an early fault line when different feeder synonym phase two-point grounding types are used according to an alternative embodiment of the present invention;

fig. 4(c) is a schematic diagram of a three-phase current waveform of an initial fault line in different feeder line different phase two-point grounding types according to an alternative embodiment of the present invention;

fig. 4(d) is a schematic diagram of a zero sequence current waveform when different feeder line different phase two-point grounding types according to an alternative embodiment of the present invention;

fig. 4(e) is a schematic diagram of a zero sequence current waveform of an early fault line when different feeder lines are of different phase two-point grounding type according to an alternative embodiment of the present invention;

fig. 4(f) is a schematic diagram of a zero sequence current waveform of an initial fault line when different feeder lines are different in name phase two-point grounding type according to an alternative embodiment of the present invention;

FIG. 5 is a schematic illustration of the duration of a perturbation according to an alternative embodiment of the present invention;

FIG. 6 is a flow chart of a low current grounding system ground type early fault identification method in accordance with an alternative embodiment of the present invention;

FIG. 7 is a critical curve for identification of different types of early faults, according to an alternative embodiment of the present invention.

Fig. 8 is a schematic diagram of an early failure type identification apparatus according to an embodiment of the present invention.

Detailed Description

The following description of the embodiments of the present invention is provided to facilitate the understanding of the present invention by those skilled in the art, but it should be understood that the present invention is not limited to the scope of the embodiments, and it will be apparent to those skilled in the art that various changes may be made without departing from the spirit and scope of the invention as defined and defined in the appended claims, and all matters produced by the invention using the inventive concept are protected.

It should be noted that the terms "first," "second," and the like in the description and claims of the present invention and in the drawings described above are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the invention described herein are capable of operation in sequences other than those illustrated or described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.

Example 1

In accordance with an embodiment of the present invention, there is provided an embodiment of a method for early failure type identification, it being noted that the steps illustrated in the flowchart of the drawings may be performed in a computer system such as a set of computer-executable instructions and that, although a logical order is illustrated in the flowchart, in some cases the steps illustrated or described may be performed in an order different than presented herein.

Fig. 1 is a flowchart of an early failure type identification method according to an embodiment of the present invention, as shown in fig. 1, the method includes the following steps:

step S102, disturbance waveform data of a disturbance event are collected, wherein the disturbance waveform data at least comprise: the disturbance duration of early fault, the initial fault phase angle of voltage and the load current variation;

in an optional implementation manner, disturbance waveform data can be collected by the station-side disturbance waveform recording device, so that the early fault disturbance duration of a disturbance event, the fault initial phase angle of a voltage and the load current variation are obtained.

Step S104, judging whether the early fault disturbance duration is within the early fault time range, if so, judging whether the fault initial phase angle of the voltage is within the margin range of the voltage peak value, and if not, continuously acquiring disturbance waveform data of a disturbance event;

step S106, when judging whether the initial fault phase angle of the voltage is in the margin range of the voltage peak value, if so, judging whether the load current variation is less than or equal to a set current threshold value, and if not, continuously acquiring disturbance waveform data of a disturbance event;

step S108, when judging whether the load current variation is less than or equal to the set current threshold, if so, executing a first group of criteria, and if not, executing a second group of criteria;

step S110, according to the first group of criteria or the second group of criteria, the early failure type of the disturbance event is identified.

In an alternative embodiment, the early failure time range, the margin range of the voltage peak value, and the set current threshold value may be set according to the requirements of the actual application scenario.

In an alternative embodiment, the early fault type of the disturbance event is identified according to the first group of criteria or the second group of criteria, and whether the disturbance event is a single-phase grounding type or a different-name two-point grounding type early fault can be accurately judged through the embodiment.

It should be noted that the method in the above-mentioned implementation steps S102 to S110 can be applied to the identification of the early fault of the low-current grounding system.

Through the steps, the diversity of early fault expression forms in the system can be fully considered aiming at the operation characteristics of the small current grounding system, and the early fault of the disturbance event is identified based on the composite criterion, so that the technical effect of accurately identifying the grounding type early fault of the small current grounding system is realized, and the technical problem of how to identify the single-phase grounding type early fault and the different-name two-point grounding type early fault in the small current grounding system is solved.

Optionally, the early failure time range is [5ms, 80ms ].

Optionally, the margin range of the voltage peak is

Wherein k is a natural number, epsilon is a voltage peak margin, and epsilon belongs to [5-10 DEG ]]。

Optionally, the current threshold is set to σ₁I_N，σ₁＝5％，σ₁Is a first scale factor, I_NIs the nominal phase current of the line.

Optionally, performing the first set of criteria comprises the sub-steps of: judging whether the half-wave effective value of the current of one phase is greater than mu I_NIf yes, judging whether the effective value of the zero sequence voltage of the first cycle before the disturbance starting moment and the zero sequence voltage of the first cycle after the disturbance ending moment are both larger than or equal to beta₁V_NAnd whether the effective value of the zero sequence current of the first cycle before the disturbance starting moment and the zero sequence current of the first cycle after the disturbance ending moment are both greater than or equal to beta₂I_NIf not, judging whether the effective value of the zero sequence voltage of the first cycle before the disturbance starting moment and the zero sequence voltage of the first cycle after the disturbance ending moment are both smaller than beta₁V_NAnd whether the effective value of the zero sequence current of the first cycle before the disturbance starting moment and the zero sequence current of the first cycle after the disturbance ending moment are both less than beta₂I_NWhere μ is the proportionality coefficient of the phase current, I_NIs the rated phase current of the line; judging whether the zero sequence voltage effective value of the first cycle before the disturbance starting moment and the zero sequence voltage of the first cycle after the disturbance ending moment are both greater than or equal to beta₁V_NAnd whether the effective value of the zero sequence current of the first cycle before the disturbance starting moment and the zero sequence current of the first cycle after the disturbance ending moment are both greater than or equal to beta₂I_NIf so, judging whether the effective value of the zero sequence voltage of the first cycle before the disturbance starting moment and the zero sequence voltage of the first cycle after the disturbance ending moment meet a first voltage difference inequality, and judging whether the zero sequence voltage of the first cycle before the disturbance starting moment meets the first voltage difference inequality or notWhether the current effective value and the zero sequence current of the first cycle after the disturbance termination time meet a first current difference inequality or not, if not, continuously acquiring disturbance waveform data of a disturbance event, wherein beta is beta₁Is a first scale parameter, beta₂Is a first scale parameter, V_NIs the rated phase voltage of the line; when judging whether the effective value of the zero-sequence voltage of the first cycle before the disturbance starting moment and the zero-sequence voltage of the first cycle after the disturbance terminating moment meet a first voltage difference inequality, and whether the effective value of the zero-sequence current of the first cycle before the disturbance starting moment and the zero-sequence current of the first cycle after the disturbance terminating moment meet a first current difference inequality, if so, the early fault type of the disturbance event is a different-name-phase two-point grounding type early fault, and if not, the disturbance waveform data of the disturbance event is continuously acquired; judging whether the zero sequence voltage effective value of the first cycle before the disturbance starting moment and the zero sequence voltage of the second cycle after the disturbance ending moment are both less than beta₁V_NAnd whether the effective value of the zero sequence current of the first cycle before the disturbance starting moment and the zero sequence current of the first cycle after the disturbance ending moment are both less than beta₂I_NIf yes, judging the effective value V of the full wave of the zero sequence voltage_0rmsWhether or not the maximum value of (b) is greater than lambdav_NIf not, continuing to acquire disturbance waveform data of the disturbance event; after judging zero sequence voltage full wave effective value V_0rmsWhether or not the maximum value of (b) is greater than lambdav_NIf the single-phase grounding type early fault exists, the early fault type of the disturbance event is the single-phase grounding type early fault, and if the single-phase grounding type early fault does not exist, whether the half-wave effective value of the current of one phase is larger than mu I or not is continuously judged_NWherein, λ is a proportionality coefficient.

Optionally, the first voltage difference inequality is: i V_0before-V_0after|<σ₂V_NThe first current difference inequality is: i_0before-I_0after|<σ₃V_NWherein V is_0beforeFor disturbing the zero-sequence voltage effective value, V, of the previous cycle at the start time_0afterZero sequence voltage of a cycle after the disturbance termination time, I_0beforeFor disturbing the zero-sequence current effective value of the previous cycle, I_0afterAfter the disturbance termination momentZero sequence current of one cycle, σ₂Is the second proportionality coefficient, σ₃Is the third scaling factor.

Through the implementation mode, the early-stage fault can be accurately identified, and the type of the early-stage fault can be further identified, namely the early-stage fault of the single-row grounding type or the different-name two-point grounding type is judged to be disturbed.

Optionally, performing the second set of criteria comprises the sub-steps of: judging whether the load current after the disturbance is reduced relative to the load current before the disturbance, if so, judging whether the half-wave effective value exceeding one-phase current is greater than mu I_NIf not, continuing to acquire disturbance waveform data of the disturbance event; judging whether the half-wave effective value of the current exceeding one phase is greater than mu I_NIf yes, judging whether the effective value of the zero sequence voltage of the previous cycle at the disturbance starting moment is more than or equal to beta or not₁V_NAnd whether the zero sequence voltage of a cycle of wave after the disturbance termination moment is less than beta or not₁V_NAnd whether the effective value of the zero-sequence current of the first cycle wave before the disturbance starting moment is more than or equal to beta or not₂I_NAnd whether the zero sequence current of a cycle of wave after the disturbance termination moment is less than beta or not₂I_NIf not, continuing to acquire disturbance waveform data of the disturbance event, wherein mu is a proportionality coefficient of rated phase current, and I_NIs the rated phase current of the line; judging whether the zero sequence voltage effective value of the previous cycle at the disturbance starting moment is more than or equal to beta₁V_NAnd whether the zero sequence voltage of a cycle of wave after the disturbance termination moment is less than beta or not₁V_NAnd whether the effective value of the zero-sequence current of the first cycle wave before the disturbance starting moment is more than or equal to beta or not₂I_NAnd whether the zero sequence current of a cycle of wave after the disturbance termination moment is less than beta or not₂I_NIf so, judging whether the effective value of the zero sequence voltage of the first cycle before the disturbance starting moment and the zero sequence voltage of the first cycle after the disturbance ending moment meet a second voltage difference inequality, and whether the effective value of the zero sequence current of the first cycle before the disturbance starting moment and the zero sequence current of the first cycle after the disturbance ending moment meet a second current difference inequality, if not, continuously acquiring the disturbance event of the disturbance eventWaveform data of, wherein₁Is a first scale parameter, beta₂Is a first scale parameter; and if the type of the early fault of the disturbance event is the different-name phase two-point grounding type early fault, if not, continuously acquiring disturbance waveform data of the disturbance event.

Optionally, the second voltage difference inequality is: i V_0before-V_0after|≥σ₂V_NThe second current difference inequality is: i_0before-I_0after|≥σ₃V_NWherein V is_0beforeFor disturbing the zero-sequence voltage effective value, V, of the previous cycle at the start time_0afterZero sequence voltage of a cycle after the disturbance termination time, I_0beforeFor disturbing the zero-sequence current effective value of the previous cycle, I_0afterFor zero-sequence currents of a cycle after the termination of a disturbance₂Is the second proportionality coefficient, σ₃Is the third scaling factor.

It should be noted that a different-name two-point grounding type early failure may have a special case where the initial failure and the early failure occur at the same location, in which case the system is restored to a normal state when the failure is cleared. With the above embodiment, it is possible to accurately identify a special case of a different-name two-point grounding type early failure.

An alternative embodiment of the invention is described in detail below.

1. Analysis of grounding type early fault expression mode in small current grounding system:

the medium-voltage distribution network mainly adopts low-current grounding (including neutral point grounding and arc suppression coil grounding), the single-phase grounding fault current of the system is low, the system is allowed to continue to operate for 2 hours after the single-phase grounding fault, and the non-fault phase voltage is increased to the line voltage (1.732 times of the rated phase voltage). Thus, there may be two cases of early failure of a low current grounding system:

(1) during normal operation of the system, transient single-phase grounding occurring at the time of peak of the phase voltage may be referred to as "single-phase grounding type early fault", and its disturbance waveform is shown in fig. 2.

(2) When a permanent single-phase earth fault exists in the system, during 2 hours of continuous operation of the system, the non-fault phase voltage is increased, so that the insulation weak point is broken down at the moment of voltage peak, and the fault point is represented as an earth fault of a certain phase, and the fault point is represented as a two-point earth fault of a different-name phase at the system level. When the fault is a transient breakdown (early fault), this type of fault perturbation may be referred to as a "heteronymous two-point grounded early fault". Depending on the location of the initial fault and the second transient breakdown, such early faults may occur on the same feeder or on different feeders, with the disturbance waveforms shown in fig. 3 and 4.

Wherein, the initial state of the single-phase grounding type early fault is a healthy state; the initial state of the different-name phase two-point grounding type early fault is a single-phase grounding fault state. Because the early fault has self-clearing property, the system recovers to a normal state after the single-phase grounding type early fault is self-cleared; the system generally recovers the single-phase earth fault state after the different-name two-point earth type early fault is self-cleared, but may also recover to the normal state when the initial fault and the early fault are located at the same position.

2. An alternative embodiment of the present invention relates to the extraction of feature quantities:

due to the particularity of the operation of the low-current grounding system, the early failure of the system is divided into a single-phase grounding type and a synonym phase two-point grounding type.

The optional implementation mode of the invention is to provide a small current grounding system grounding type early fault identification method based on composite criterion according to early fault disturbance waveform characteristic analysis and considering phase voltage/current and zero sequence voltage/current at the same time.

The calculation process of the criterion relating to the feature quantity is explained below.

According to station-side disturbance waveformExtracting disturbance characteristic vector from disturbance waveform data collected by recording device

Where at is the perturbation duration,

for the initial phase angle of failure, Δ I, of the voltage_loadAs a change amount of load current, I_rmsA，I_rmsB，I_rmsCRespectively, the effective value of half-wave of each phase current, V_rms0、I_rms0The zero sequence voltage and the current half-wave effective value are respectively.

1) Respectively calculating the half-wave effective value I of each phase current_rmsA，I_rmsB，I_rmsC：

Wherein N is_halfThe number of sampling points per half cycle is shown, x is the phase (x: A, B, C), i_xRepresenting the instantaneous sample values of the phase current, n representing the sequence of sample points, and m representing the current sequence of sample points.

2) Respectively calculating half-wave effective values V of zero-sequence voltage and current_rms0、I_rms0。

Zero sequence voltage and current are respectively equal to one third of the sum of instantaneous values, and half-wave effective value calculation process and calculation I_rmsxThe formula of (m) is the same. The zero sequence voltage and current effective values of the previous cycle at the disturbance starting moment are respectively V_0before、I_0beforeThe zero sequence voltage and current of one cycle after the disturbance termination time are respectively V_0after、I_0after。

3) Calculating the disturbance starting and stopping time t₁、t₂And a perturbation duration Δ t. As shown in fig. 5, the effective value of the half-wave of the voltage or current (determined by the triggering criterion, such as when the disturbance is triggered by a sudden change in voltage, the effective value of the voltage is selected here) is found to be equal to the threshold value λ₀Time of day t₁And t₂Respectively, respectivelyAs the disturbance start-stop time, the disturbance duration Δ t is t₂-t₁。

4) Calculating the initial phase angle of voltage fault

The formula of (1) is:

wherein v (x) is a voltage sampling signal, r is a natural number, a_r、b_rThe amplitudes of the cosine and sine terms of each harmonic, respectively, a when r is 1₁、b₁The cosine term and sine term amplitudes of the fundamental component, respectively. Considering omega₁t is 2k pi/N, N is the number of sampling points in one period, a₁、b₁Can be expressed as:

wherein v is_kFor the kth sampled value of the voltage signal, at which time the fault initial phase angle of the voltage

Can be expressed as:

it is noted that for a₁、b₁The sampling data calculated by the formula (2) is N sampling points before the disturbance starting moment, namely the sampling signal of the cycle before the fault occurs.

5) Calculating load current variation delta I_load. According to a₁、b₁The fundamental current signal is calculated in the same way, and the sudden change quantity of the fundamental current in adjacent periods is calculated to maximize the sudden change quantityAs a perturbation phase. According to I_rmsA，I_rmsB，I_rmsCThe effective value of the half-wave of the fundamental wave current signal in the period before the disturbance starting moment and the period after the disturbance ending moment is calculated, and the absolute value of the difference between the two is the load current variation delta I_load。

Wherein n is₁Representing the corresponding sample point at the start of the disturbance, n₂Representing a sampling point corresponding to the disturbance ending moment; n is the number of sampling points in a period; k is a radical of₁For disturbing the sampling point of the previous cycle, k₁∈(n₁-N，n₁)，k₂For sampling points, k, of a period after the end of the disturbance₂∈(n₂，n₂+N)；

To perturb the current sample signal transient during the previous cycle,

and sampling the instantaneous value of the signal for the current in a period after the disturbance is finished.

3. The specific implementation steps of the optional implementation mode of the invention are as follows:

as shown in fig. 6, a method for identifying a ground-type early fault of a low-current grounding system includes the following steps:

s1, acquiring disturbance waveform data through a station end disturbance waveform recording device to obtain the early fault disturbance duration of a disturbance event, the fault initial phase angle of voltage and the load current variation;

in the step S2, the early fault time range is [5ms, 80ms ], the early fault disturbance duration is 1/4-4 cycles, and therefore, the Δ t needs to satisfy that the Δ t is more than or equal to 5ms and less than or equal to 80 ms.

S2, judging whether the early fault disturbance duration of the disturbance event is within the early fault time range, if so, jumping to S3, and if not, jumping to S1;

s3, judging whether the fault initial phase angle of the voltage of the disturbance event is within the margin range of the voltage peak value, if so, jumping to the step S4, and if not, jumping to the step S1;

the margin range of the voltage peak in step S3 is

Wherein k is a natural number, epsilon is a voltage peak margin, and epsilon belongs to [5-10 DEG ]]The early fault is determined to occur near the moment of the voltage peak.

Early fault disturbance is self-clearing and does not cause traditional overcurrent protection action, so that the load current generally does not change before and after disturbance occurs.

S4, judging whether the load current variation is less than or equal to the set current threshold, if so, executing a first group of criteria, if not, judging whether the disturbance is a different-name phase two-point grounding type early fault occurring at the same position, executing a second group of criteria, and identifying the early fault type of the disturbance event, namely judging whether the disturbance event is a single-phase grounding type or a different-name phase two-point grounding type early fault.

In step S4, the current threshold is set to σ₁I_N，σ₁＝5％，σ₁Is a first scale factor, I_NThe nominal phase current for that line.

The method of performing the first set of criteria in step S4 includes the sub-steps of:

a1, judging whether the half-wave effective value of the current of one phase is larger than mu I_NIf yes, jumping to step A2, otherwise, jumping to step A4, where mu is the proportionality coefficient of phase current, I_NThe rated phase current of the line;

a2, judging whether the effective value of the zero sequence voltage of the first cycle before the disturbance starting moment and the zero sequence voltage of the first cycle after the disturbance ending moment are both more than or equal to beta₁V_NAnd whether the effective value of the zero sequence current of the first cycle before the disturbance starting moment and the zero sequence current of the first cycle after the disturbance ending moment are both larger than equalIn beta₂I_NIf yes, go to step A3, if no, go to step S1, wherein β₁Is a first scale parameter, beta₂Is a first scale parameter, V_NThe rated phase voltage of the line;

a3, judging whether the effective value of the zero sequence voltage of the first cycle before the disturbance starting moment and the zero sequence voltage of the first cycle after the disturbance ending moment meet a first voltage difference inequality, and whether the effective value of the zero sequence current of the first cycle before the disturbance starting moment and the zero sequence current of the first cycle after the disturbance ending moment meet a first current difference inequality, if yes, the early fault type of the disturbance event is a different-name-phase two-point grounding type early fault, ending the substep, and if not, jumping to the step S1;

a4, judging whether the effective value of the zero sequence voltage of the first cycle before the disturbance starting moment and the zero sequence voltage of the first cycle after the disturbance ending moment are both less than beta₁V_NAnd whether the effective value of the zero sequence current of the first cycle before the disturbance starting moment and the zero sequence current of the first cycle after the disturbance ending moment are both less than beta₂I_NIf yes, jumping to step A5, if no, jumping to step S1;

a5, judging zero sequence voltage full wave effective value V_0rmsWhether or not the maximum value of (b) is greater than lambdav_NIf yes, the early fault type of the disturbance event is a single-phase grounding type early fault, the substep is ended, and if not, the step is skipped to step S1, wherein λ is a proportionality coefficient.

The first voltage difference inequality in step a3 is: i V_0before-V_0after|<σ₂V_NThe first current difference inequality is: i_0before-I_0after|<σ₃V_N；

Wherein, V_0beforeFor disturbing the zero-sequence voltage effective value, V, of the previous cycle at the start time_0afterZero sequence voltage of a cycle after the disturbance termination time, I_0beforeFor disturbing the zero-sequence current effective value of the previous cycle, I_0afterFor zero-sequence currents of a cycle after the termination of a disturbance₂Is the second proportionality coefficient, σ₃Is the third scaling factor.

Further, the method for executing the second set of criteria in step S4 includes the sub-steps of:

b1, judging whether the load current after the disturbance is reduced relative to the load current before the disturbance, if so, jumping to the step B2, and if not, jumping to the step S1;

b2, judging whether the half-wave effective value of the more than one phase current is larger than mu I_NIf yes, go to step B3, otherwise, go to step S1, where mu is the proportionality coefficient of the rated phase current, I_NThe rated phase current of the line;

b3, judging whether the zero sequence voltage effective value of the previous cycle of the disturbance starting moment is more than or equal to beta or not₁V_NAnd whether the zero sequence voltage of a cycle of wave after the disturbance termination moment is less than beta or not₁V_NAnd whether the effective value of the zero-sequence current of the first cycle wave before the disturbance starting moment is more than or equal to beta or not₂I_NAnd whether the zero sequence current of a cycle of wave after the disturbance termination moment is less than beta or not₂I_NIf yes, go to step B4, if no, go to step S1, wherein β₁Is a first scale parameter, beta₂Is a first scale parameter;

b4, judging whether the effective value of the zero-sequence voltage of the first cycle before the disturbance starting moment and the zero-sequence voltage of the first cycle after the disturbance ending moment meet a second voltage difference inequality, judging whether the effective value of the zero-sequence current of the first cycle before the disturbance starting moment and the zero-sequence current of the first cycle after the disturbance ending moment meet the second current difference inequality, if so, judging that the early fault type of the disturbance event is a different-name-phase two-point grounding type early fault, ending the substep, and if not, jumping to the step S1.

The second voltage difference inequality in step B4 is: i V_0before-V_0after|≥σ₂V_NThe second current difference inequality is: i_0before-I_0after|≥σ₃V_N；

Wherein, V_0beforeFor disturbing zero sequence voltage effective value of one cycle before starting time，V_0afterZero sequence voltage of a cycle after the disturbance termination time, I_0beforeFor disturbing the zero-sequence current effective value of the previous cycle, I_0afterFor zero-sequence currents of a cycle after the termination of a disturbance₂Is the second proportionality coefficient, σ₃Is the third scaling factor.

In this embodiment, μ ═ 118%, β₁＝3.5％，β₂＝4％，λ＝8.9％，σ₂＝25％，σ₃＝10％。

The correctness of the method is verified according to the measured data, the influence of system parameters and fault parameters on the method is considered, and the sensitivity of the method is verified. Fig. 7 is a critical curve for identifying different types of early faults, and it can be seen from fig. 7 that the fault resistance has a large influence on the algorithm, and the algorithm has different detection capabilities for different types of early faults under the same fault resistance condition. The method has stronger detection capability on different-name phase two-point grounding type early faults of different feeder lines, and the initial fault phase current is more obvious when the faults occur. In addition, the different types of ground type early fault identification critical curves are less affected by the fault distance. The method can accurately identify the early fault with the fault resistance smaller than 800 omega according to the actual measurement result, and meets the actual requirement, thereby proving the effectiveness of the method.

Example 2

According to another aspect of the embodiments of the present invention, there is also provided an early failure type identification apparatus, and fig. 8 is a schematic diagram of the early failure type identification apparatus according to the embodiments of the present invention, as shown in fig. 8, the early failure type identification apparatus includes: an acquisition module 802, a first judgment module 804, a second judgment module 806, a third judgment module 808, and an identification module 810. The early failure type identification means will be described in detail below.

An acquisition module 802, configured to acquire disturbance waveform data of a disturbance event, where the disturbance waveform data at least includes: the disturbance duration of early fault, the initial fault phase angle of voltage and the load current variation; a first determining module 804, connected to the acquiring module 802, for determining whether the early-stage fault disturbance duration is within an early-stage fault time range, if so, determining whether a fault initial phase angle of the voltage is within a margin range of a voltage peak, and if not, continuing to acquire disturbance waveform data of the disturbance event; a second determining module 806, connected to the first determining module 804, configured to, when determining whether the fault initial phase angle of the voltage is within a margin range of a voltage peak, if so, determine whether a load current variation is less than or equal to a set current threshold, and if not, continue to acquire disturbance waveform data of the disturbance event; a third determining module 808, connected to the second determining module 806, configured to execute the first set of criteria if the load current variation is smaller than or equal to the set current threshold, and execute the second set of criteria if the load current variation is not smaller than the set current threshold; an identification module 810, coupled to the third determination module 808, is configured to identify an early failure type of the disturbance event according to the first set of criteria or the second set of criteria.

In the above embodiment, the early fault type identification device can fully consider the diversity of the early fault expression forms in the system by aiming at the operating characteristics of the low-current grounding system, and identify the early fault of the disturbance event based on the composite criterion, thereby realizing the technical effect of accurately identifying the grounding type early fault of the low-current grounding system, and further solving the technical problem of how to identify the single-phase grounding type early fault and the different-name-phase two-point grounding type early fault in the low-current grounding system.

It should be noted that the above modules may be implemented by software or hardware, for example, for the latter, the following may be implemented: the modules can be located in the same processor; and/or the modules are located in different processors in any combination.

It should be noted here that the above-mentioned acquisition module 802, first judgment module 804, second judgment module 806, third judgment module 808 and identification module 810 correspond to steps S102 to S110 in embodiment 1, and the above-mentioned modules are the same as the corresponding steps in the implementation example and application scenario, but are not limited to the content disclosed in embodiment 1.

Example 3

According to another aspect of the embodiments of the present invention, there is also provided a computer-readable storage medium, which includes a stored program, wherein when the program runs, an apparatus in which the computer-readable storage medium is located is controlled to execute the method for identifying an early failure type in any one of the above.

Optionally, in this embodiment, the computer-readable storage medium may be located in any one of a group of computer terminals in a computer network and/or in any one of a group of mobile terminals, and the computer-readable storage medium includes a stored program.

Optionally, the program when executed controls an apparatus in which the computer-readable storage medium is located to perform the following functions: acquiring disturbance waveform data of a disturbance event, wherein the disturbance waveform data at least comprises: the disturbance duration of early fault, the initial fault phase angle of voltage and the load current variation; judging whether the early fault disturbance duration is within the early fault time range, if so, judging whether the fault initial phase angle of the voltage is within the margin range of the voltage peak value, and if not, continuously acquiring disturbance waveform data of the disturbance event; when judging whether the initial fault phase angle of the voltage is in the margin range of the voltage peak value, if so, judging whether the load current variation is less than or equal to a set current threshold value, and if not, continuously acquiring disturbance waveform data of a disturbance event; when judging whether the load current variation is smaller than or equal to a set current threshold value, if so, executing a first group of criteria, and if not, executing a second group of criteria; the early failure type of the disturbance event is identified based on either the first set of criteria or the second set of criteria.

Example 4

According to another aspect of the embodiments of the present invention, there is also provided a processor, configured to execute a program, where the program executes the method for identifying the early failure type in any one of the above.

The embodiment of the invention provides equipment, which comprises a processor, a memory and a program which is stored on the memory and can run on the processor, wherein the processor executes the program and realizes the following steps: acquiring disturbance waveform data of a disturbance event, wherein the disturbance waveform data at least comprises: the disturbance duration of early fault, the initial fault phase angle of voltage and the load current variation; judging whether the early fault disturbance duration is within the early fault time range, if so, judging whether the fault initial phase angle of the voltage is within the margin range of the voltage peak value, and if not, continuously acquiring disturbance waveform data of the disturbance event; when judging whether the initial fault phase angle of the voltage is in the margin range of the voltage peak value, if so, judging whether the load current variation is less than or equal to a set current threshold value, and if not, continuously acquiring disturbance waveform data of a disturbance event; when judging whether the load current variation is smaller than or equal to a set current threshold value, if so, executing a first group of criteria, and if not, executing a second group of criteria; the early failure type of the disturbance event is identified based on either the first set of criteria or the second set of criteria.

The invention also provides a computer program product adapted to perform a program for initializing the following method steps when executed on a data processing device: acquiring disturbance waveform data of a disturbance event, wherein the disturbance waveform data at least comprises: the disturbance duration of early fault, the initial fault phase angle of voltage and the load current variation; judging whether the early fault disturbance duration is within the early fault time range, if so, judging whether the fault initial phase angle of the voltage is within the margin range of the voltage peak value, and if not, continuously acquiring disturbance waveform data of the disturbance event; when judging whether the initial fault phase angle of the voltage is in the margin range of the voltage peak value, if so, judging whether the load current variation is less than or equal to a set current threshold value, and if not, continuously acquiring disturbance waveform data of a disturbance event; when judging whether the load current variation is smaller than or equal to a set current threshold value, if so, executing a first group of criteria, and if not, executing a second group of criteria; the early failure type of the disturbance event is identified based on either the first set of criteria or the second set of criteria.

The above-mentioned serial numbers of the embodiments of the present invention are merely for description and do not represent the merits of the embodiments.

In the above embodiments of the present invention, the descriptions of the respective embodiments have respective emphasis, and for parts that are not described in detail in a certain embodiment, reference may be made to related descriptions of other embodiments.

In the embodiments provided in the present application, it should be understood that the disclosed technology can be implemented in other ways. The above-described embodiments of the apparatus are merely illustrative, and for example, the division of the units may be a logical division, and in actual implementation, there may be another division, for example, multiple units or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, units or modules, and may be in an electrical or other form.

The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.

In addition, functional units in the embodiments of the present invention may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit. The integrated unit can be realized in a form of hardware, and can also be realized in a form of a software functional unit.

The integrated unit, if implemented in the form of a software functional unit and sold or used as a stand-alone product, may be stored in a computer readable storage medium. 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 Read-Only Memory (ROM), a Random Access Memory (RAM), a removable hard disk, a magnetic or optical disk, and other various media capable of storing program codes.

Claims

1. A method for identifying an early failure type, comprising:

acquiring disturbance waveform data of a disturbance event, wherein the disturbance waveform data at least comprises: the disturbance duration of early fault, the initial fault phase angle of voltage and the load current variation;

judging whether the early fault disturbance duration is within an early fault time range, if so, judging whether a fault initial phase angle of the voltage is within a margin range of a voltage peak value, and if not, continuously acquiring the disturbance waveform data of the disturbance event;

when judging whether the initial fault phase angle of the voltage is in the margin range of the voltage peak value, if so, judging whether the load current variation is less than or equal to a set current threshold value, and if not, continuously acquiring the disturbance waveform data of the disturbance event;

when judging whether the load current variation is smaller than or equal to a set current threshold value, if so, executing a first group of criteria, and if not, executing a second group of criteria;

identifying an early failure type of the disturbance event based on the first set of criteria or the second set of criteria.

2. The method of claim 1, wherein the early failure time range is [5ms, 80ms ].

3. The method of claim 1, wherein the voltage peak has a margin in the range of

Where k is a natural number and ε is the voltage peak margin.

4. The method of claim 1, wherein the set current threshold is σ₁I_N，σ₁＝5％，σ₁Is a first scale factor, I_NIs the nominal phase current of the line.

5. The method of any of claims 1-4, wherein performing a first set of criteria comprises:

judging whether the half-wave effective value of the current of one phase is greater than mu I_NIf yes, judging whether the effective value of the zero sequence voltage of the first cycle before the disturbance starting moment and the zero sequence voltage of the first cycle after the disturbance ending moment are both larger than or equal to beta₁V_NAnd whether the effective value of the zero sequence current of the first cycle before the disturbance starting moment and the zero sequence current of the first cycle after the disturbance ending moment are both greater than or equal to beta₂I_NIf not, judging whether the effective value of the zero sequence voltage of the first cycle before the disturbance starting moment and the zero sequence voltage of the first cycle after the disturbance ending moment are both smaller than beta₁V_NAnd whether the effective value of the zero sequence current of the first cycle before the disturbance starting moment and the zero sequence current of the first cycle after the disturbance ending moment are both less than beta₂I_NWhere μ is the proportionality coefficient of the phase current, I_NIs the rated phase current of the line;

judging whether the zero sequence voltage effective value of the first cycle before the disturbance starting moment and the zero sequence voltage of the first cycle after the disturbance ending moment are both greater than or equal to beta₁V_NAnd whether the effective value of the zero sequence current of the first cycle before the disturbance starting moment and the zero sequence current of the first cycle after the disturbance ending moment are both greater than or equal to beta₂I_NIf so, judging whether the effective value of the zero sequence voltage of the first cycle before the disturbance starting moment and the zero sequence voltage of the first cycle after the disturbance ending moment meet a first voltage difference inequality, and judging whether the effective value of the zero sequence current of the first cycle before the disturbance starting moment and the disturbance of the zero sequence current of the first cycle before the disturbance ending moment meet the first voltage difference inequalityWhether the zero sequence current of the first cycle after the dynamic termination moment meets a first current difference inequality or not is judged, if not, the disturbance waveform data of the disturbance event are continuously acquired, wherein beta is beta₁Is a first scale parameter, beta₂Is a first scale parameter, V_NIs the rated phase voltage of the line;

when judging whether the effective value of the zero-sequence voltage of the first cycle before the disturbance starting moment and the zero-sequence voltage of the first cycle after the disturbance terminating moment meet a first voltage difference inequality, and whether the effective value of the zero-sequence current of the first cycle before the disturbance starting moment and the zero-sequence current of the first cycle after the disturbance terminating moment meet a first current difference inequality, if so, the early fault type of the disturbance event is a different-name-phase two-point grounding type early fault, and if not, the disturbance waveform data of the disturbance event is continuously acquired;

judging whether the zero sequence voltage effective value of the first cycle before the disturbance starting moment and the zero sequence voltage of the second cycle after the disturbance ending moment are both less than beta₁V_NAnd whether the effective value of the zero sequence current of the first cycle before the disturbance starting moment and the zero sequence current of the first cycle after the disturbance ending moment are both less than beta₂I_NIf yes, judging the effective value V of the full wave of the zero sequence voltage_0rmsWhether or not the maximum value of (b) is greater than lambdav_NIf not, continuing to acquire the disturbance waveform data of the disturbance event;

after judging zero sequence voltage full wave effective value V_0rmsWhether or not the maximum value of (b) is greater than lambdav_NIf the single-phase grounding type early fault exists, the early fault type of the disturbance event is a single-phase grounding type early fault, and if the single-phase grounding type early fault does not exist, whether the half-wave effective value of the current of one phase is larger than mu I or not is continuously judged_NWherein, λ is a proportionality coefficient.

6. The method of claim 5, wherein the first voltage difference value inequality is: i V_0before-V_0after|<σ₂V_NThe first current difference inequality is: i_0before-I_0after|<σ₃V_NWherein V is_0beforeFor the start of disturbanceZero sequence voltage effective value, V, of a cycle before a moment_0afterZero sequence voltage of a cycle after the disturbance termination time, I_0beforeFor disturbing the zero-sequence current effective value of the previous cycle, I_0afterFor zero-sequence currents of a cycle after the termination of a disturbance₂Is the second proportionality coefficient, σ₃Is the third scaling factor.

7. The method of any of claims 1-4, wherein performing a second set of criteria comprises:

judging whether the load current after the disturbance is reduced relative to the load current before the disturbance, if so, judging whether the half-wave effective value exceeding one-phase current is greater than mu I_NIf not, continuing to acquire the disturbance waveform data of the disturbance event;

judging whether the half-wave effective value of the current exceeding one phase is greater than mu I_NIf yes, judging whether the effective value of the zero sequence voltage of the previous cycle at the disturbance starting moment is more than or equal to beta or not₁V_NAnd whether the zero sequence voltage of a cycle of wave after the disturbance termination moment is less than beta or not₁V_NAnd whether the effective value of the zero-sequence current of the first cycle wave before the disturbance starting moment is more than or equal to beta or not₂I_NAnd whether the zero sequence current of a cycle of wave after the disturbance termination moment is less than beta or not₂I_NIf not, continuing to acquire the disturbance waveform data of the disturbance event, wherein mu is a proportionality coefficient of rated phase current, and I_NIs the rated phase current of the line;

judging whether the zero sequence voltage effective value of the previous cycle at the disturbance starting moment is more than or equal to beta₁V_NAnd whether the zero sequence voltage of a cycle of wave after the disturbance termination moment is less than beta or not₁V_NAnd whether the effective value of the zero-sequence current of the first cycle wave before the disturbance starting moment is more than or equal to beta or not₂I_NAnd whether the zero sequence current of a cycle of wave after the disturbance termination moment is less than beta or not₂I_NIf so, judging the effective value of the zero sequence voltage of the first cycle before the disturbance starting moment and the zero sequence voltage of the first cycle after the disturbance ending momentWhether the voltage meets a second voltage difference inequality, whether the effective value of the zero-sequence current of the first cycle before the disturbance starting moment and the zero-sequence current of the first cycle after the disturbance ending moment meet the second current difference inequality, and if not, continuing to acquire the disturbance waveform data of the disturbance event, wherein beta is beta₁Is a first scale parameter, beta₂Is a first scale parameter;

and if the type of the early fault of the disturbance event is a different-name phase two-point grounding type early fault, if not, continuously acquiring the disturbance waveform data of the disturbance event.

8. The method of claim 7, wherein the second voltage difference value inequality is: i V_0before-V_0after|≥σ₂V_NThe second current difference inequality is as follows: i_0before-I_0after|≥σ₃V_NWherein V is_0beforeFor disturbing the zero-sequence voltage effective value, V, of the previous cycle at the start time_0afterZero sequence voltage of a cycle after the disturbance termination time, I_0beforeFor disturbing the zero-sequence current effective value of the previous cycle, I_0afterFor zero-sequence currents of a cycle after the termination of a disturbance₂Is the second proportionality coefficient, σ₃Is the third scaling factor.

9. An early failure type identification device, comprising:

an acquisition module, configured to acquire disturbance waveform data of a disturbance event, where the disturbance waveform data at least includes: the disturbance duration of early fault, the initial fault phase angle of voltage and the load current variation;

the first judgment module is used for judging whether the early fault disturbance duration is within an early fault time range, if so, judging whether a fault initial phase angle of the voltage is within a margin range of a voltage peak value, and if not, continuously acquiring the disturbance waveform data of the disturbance event;

the second judgment module is used for judging whether the initial fault phase angle of the voltage is within the margin range of the voltage peak value, if so, judging whether the load current variation is smaller than or equal to a set current threshold value, and if not, continuously acquiring the disturbance waveform data of the disturbance event;

the third judging module is used for executing the first group of criteria if the load current variation is judged to be less than or equal to the set current threshold, and executing the second group of criteria if the load current variation is not judged to be less than or equal to the set current threshold;

an identification module configured to identify an early failure type of the disturbance event based on the first set of criteria or the second set of criteria.

10. A computer-readable storage medium, comprising a stored program, wherein when the program runs, the apparatus in which the computer-readable storage medium is located is controlled to execute the method for identifying an early failure type according to any one of claims 1 to 8.