CN114647921A - Method for simulating latent fault of medium-voltage distribution cable - Google Patents

Method for simulating latent fault of medium-voltage distribution cable Download PDF

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CN114647921A
CN114647921A CN202111424958.XA CN202111424958A CN114647921A CN 114647921 A CN114647921 A CN 114647921A CN 202111424958 A CN202111424958 A CN 202111424958A CN 114647921 A CN114647921 A CN 114647921A
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arc
medium
fault
voltage distribution
latent
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刘朝章
刘建
孙锐
王聪
田怀源
韩丙光
张文山
毛忠浩
高俊营
张小虎
张付东
徐京睿
韩立群
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State Grid Corp of China SGCC
Dezhou Power Supply Co of State Grid Shandong Electric Power Co Ltd
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State Grid Corp of China SGCC
Dezhou Power Supply Co of State Grid Shandong Electric Power Co Ltd
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    • G06—COMPUTING; CALCULATING OR COUNTING
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    • G06F30/00—Computer-aided design [CAD]
    • G06F30/20—Design optimisation, verification or simulation
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06Q—INFORMATION AND COMMUNICATION TECHNOLOGY [ICT] SPECIALLY ADAPTED FOR ADMINISTRATIVE, COMMERCIAL, FINANCIAL, MANAGERIAL OR SUPERVISORY PURPOSES; SYSTEMS OR METHODS SPECIALLY ADAPTED FOR ADMINISTRATIVE, COMMERCIAL, FINANCIAL, MANAGERIAL OR SUPERVISORY PURPOSES, NOT OTHERWISE PROVIDED FOR
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    • G06Q50/06—Electricity, gas or water supply
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    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F2113/00—Details relating to the application field
    • G06F2113/16—Cables, cable trees or wire harnesses

Abstract

The invention provides a method for simulating latent faults of a medium-voltage distribution cable, which comprises the following steps: establishing a mathematical equivalent model of the latent fault of the medium-voltage distribution cable based on a Kizilcay dynamic arc model; based on a mathematical equivalent model of the latent fault of the medium-voltage distribution cable, a typical small-resistance medium-voltage cable distribution system and a latent fault equivalent simulation model of the medium-voltage distribution cable are set up in PSCAD electromagnetic simulation software, and simulation of the latent fault of the medium-voltage distribution cable is carried out to obtain and observe an equivalent simulation waveform of the latent fault; on the basis of an equivalent simulation model, the influence of main three parameters, namely arc characteristic voltage, characteristic resistance and time constant, on fault characteristics is researched and analyzed, and simulation of medium-voltage distribution cable latent faults is realized.

Description

Method for simulating latent fault of medium-voltage distribution cable
Technical Field
The invention relates to the technical field of cable fault modeling, in particular to a method for simulating latent faults of medium-voltage distribution cables.
Background
The statements in this section merely provide background information related to the present disclosure and may not necessarily constitute prior art.
The power cable is used as key equipment for power transmission and distribution, is largely used in the construction of power transmission and distribution networks in cities due to the characteristics of attractive appearance, small occupied area, high power supply safety and the like, and meanwhile, the power supply of coastal islands, the grid connection between islands or continents, offshore oil and gas exploitation, the construction of offshore working platforms and the electric energy transmission of wind power plants also need to use the cable for power transmission;
at present, due to the influence of various factors such as cable design and production, actual operation and maintenance, operating environment and the like, cable faults occur frequently, and cables become one of potential safety hazards in the actual operation of a power grid.
Before a permanent fault occurs in a medium-voltage cable, a transient and self-recovery arc grounding fault can occur at the same position, the fault duration is short, and the fault energy is small, so that when the fault occurs, the traditional protection device cannot be started; and such faults can disappear in a short time (1/4-4 cycles), and generally do not affect the normal power transmission and distribution of the cable. Most of the faults can be developed into permanent ground faults finally, and have the characteristic of latent faults, so that the small-energy arc faults with self-recovery property occurring at the same position of the cable are called as cable latent faults, the research on the cable latent faults is beneficial to the development of cable line state maintenance, and the cable fault.
The inventors have found that when a cable has a latent fault, the conventional protection and fault indicator does not activate; and the waveform of the latent fault current has high consistency with the initial waveform of other overcurrent (such as motor starting, load transient, permanent ground fault and the like), so that difficulty is brought to the prevention, identification and protection of the latent fault.
Disclosure of Invention
In order to solve the problems, the invention provides a simulation method of the latent fault of the medium-voltage distribution cable based on an arc theory, and a medium-voltage distribution cable latent fault equivalent model is established based on a Kizilcay arc model of energy balance and control theory. And a typical low-resistance medium-voltage cable power distribution system and a medium-voltage power distribution cable latent fault equivalent simulation model are built in the PSCAD, cable latent faults are simulated, the influence of different fault parameters on latent fault arc characteristics is compared, and accurate simulation of the medium-voltage power distribution cable latent faults is achieved.
In order to realize the purpose, the invention is realized by the following technical scheme:
a method of simulating a latent fault in a medium voltage distribution cable comprising the steps of:
s1, establishing a mathematical equivalent model of the latent fault of the medium-voltage distribution cable based on the Kizilcay dynamic arc model;
s2, building a typical small-resistance medium-voltage cable power distribution system and a medium-voltage distribution cable latent fault equivalent simulation model in PSCAD electromagnetic simulation software based on a mathematical equivalent model of the medium-voltage distribution cable latent fault, and performing simulation on the medium-voltage distribution cable latent fault to obtain and observe an equivalent simulation waveform of the latent fault;
and S3, on the basis of the equivalent simulation model, researching and analyzing the influence of the main three parameters, namely arc characteristic voltage, characteristic resistance and time constant, on the fault characteristics, and realizing the simulation of the latent fault of the medium-voltage distribution cable.
In the method for simulating a latent fault of a medium voltage distribution cable, the mathematical expression of the Kizilcay dynamic arc model in step S1 is as follows:
Figure RE-GDA0003510668800000031
wherein τ is a time characteristic constant; g is the static equivalent conductance of the arc; g is the arc transient conductance and the arc transient resistance RarcThe following quantitative relationships are satisfied:
Figure RE-GDA0003510668800000032
the static equivalent conductance G of the electric arc is the electric arc homeotropic current ifAnd a static arc voltage ust(t) correlation function:
Figure RE-GDA0003510668800000033
ust(t)＝u0+r0|if(t)|
wherein u is0Is specially designed for electric arcCharacterizing a voltage; r is0Is the arc characteristic resistance;
the complete formula of the Kizilcay dynamic arc model obtained by processing the formula is as follows:
Figure RE-GDA0003510668800000034
in the method for simulating the latent fault of the medium-voltage distribution cable, in the process of establishing the mathematical equivalent model for obtaining the latent fault of the medium-voltage distribution cable based on the Kizilcay dynamic arc model, the parts, which do not generate arc discharge, in the water tree and the electric tree channel are equivalent to the constant resistance R0。
A method of simulating a latent fault in a medium voltage distribution cable as described above, the constant resistance R being applied0In series with the Kizilcay dynamic arc model, the mathematical equivalent model of the latent fault of the medium voltage distribution cable is taken as the arc transient resistance RarcThe constant resistance R equivalent to the defective channel0Get the expression as:
uf(t)＝if(t)(R0+Rarc(t))
wherein u isfVoltage for a latent fault of the medium voltage distribution cablefIs the current of a latent fault of the medium voltage distribution cable.
In the method for simulating latent faults of medium-voltage distribution cables, in step S2, a medium-voltage cable distribution system of a small-resistance system is built in the PSCAD electromagnetic simulation software by using a Bergeron cable model, and the tail end of the medium-voltage cable distribution system is connected with n cable feeders.
According to the method for simulating the latent fault of the medium-voltage distribution cable, the equivalent simulation model of the latent fault of the medium-voltage distribution cable is built on an EMTDC platform in PSCAD electromagnetic simulation software according to the parameters of the power distribution cable with the actual fault on site, and simulation is carried out.
According to the method for simulating the latent fault of the medium-voltage distribution cable, based on the single variable principle, the influence of the arc characteristic voltage on the latent fault characteristic is obtained by changing the arc characteristic voltage parameter setting, and the arc characteristic voltage and the arc size are in a negative correlation relationship.
According to the method for simulating the latent fault of the medium-voltage distribution cable, based on the single variable principle, the influence of the time characteristic constant on the latent fault characteristic is obtained by changing the parameter setting of the time characteristic constant, and the time constant is only in a negative correlation with the development trend of the first half period of the arc.
According to the method for simulating the latent fault of the medium-voltage distribution cable, the influence of the arc characteristic resistance on an arc model is not large by changing the parameter setting of the arc characteristic resistance on the basis of a single variable principle.
According to the method for simulating the latent fault of the medium-voltage distribution cable, three main parameter settings are obtained by combining different parameter sizes, and the parameter combination condition with the best fault simulation effect is as follows: the characteristic voltage u of the arc02kV, the time characteristic constant τ is 0.2ms, and the fault characteristic resistor r0＝0.005Ω。
The beneficial effects of the invention are as follows:
the invention establishes a mathematical equivalent model of the latent fault of the medium-voltage distribution cable through a Kizilcay arc model based on energy balance and control theory, a small-resistance system medium-voltage cable distribution system is established by using a Bergeron cable model in PSCAD electromagnetic simulation software, the tail end of the small-resistance system medium-voltage cable distribution system is connected with n cable feeders, the medium-voltage distribution cable latent fault equivalent simulation model is built on an EMTDC platform in PSCAD electromagnetic simulation software according to the cable parameters of the field actual fault distribution network, and performing simulation, observing simulation waveforms, researching and analyzing the influence of the main three parameters, namely arc characteristic voltage, characteristic resistance and time constant, on fault characteristics, realizing simulation of latent faults of the medium-voltage distribution cable, and finally obtaining a parameter combination with the optimal fault simulation effect of the three main parameter settings by combining different parameter sizes.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the invention and together with the description serve to explain the invention and not to limit the invention.
Fig. 1 is a diagram of phase current waveforms for different degrees of latent faults in a press-fit cable according to the present invention.
Fig. 2 is a schematic diagram of an equivalent model of the cable latent fault of the invention.
Fig. 3 is a diagram of a medium voltage cable distribution system according to the present invention in a classical low resistance system built using Bergeron cable models in PSCAD electromagnetic simulation software.
Figure 4 is a schematic view of the structure of a medium voltage distribution cable studied by the present invention.
FIG. 5 is a cable latent fault simulation model constructed by using PSACD/EMTD in the invention.
Fig. 6 is a simulation waveform of a latent fault of a medium voltage distribution cable obtained by operating a simulation model of a latent fault of a medium voltage distribution cable according to the present invention.
Fig. 7(a) is a half-cycle latent simulated fault waveform obtained by changing ten sets of fault parameters with characteristic voltage varying between 0.30-4kV, with arc characteristic resistance of 0.005 Ω and arc time constant of 0.20ms kept constant according to the present invention.
Fig. 7(b) is a period latent simulated fault waveform obtained by changing ten sets of fault parameters with characteristic voltage varying between 0.30-4kV, with arc characteristic resistance of 0.005 Ω and arc time constant of 0.20ms kept unchanged by the present invention.
Fig. 7(c) is a multi-period latent simulated fault waveform obtained by changing ten sets of fault parameters with characteristic voltage varying between 0.30-4kV, with arc characteristic resistance of 0.005 Ω and arc time constant of 0.20ms kept constant according to the present invention.
Fig. 8(a) is a half-cycle latent simulated fault waveform obtained by changing ten sets of fault parameters of which the arc characteristic resistance varies between 0.005 Ω -0.015 Ω while keeping the arc characteristic voltage at 2kV and the arc time characteristic constant at 0.20ms according to the present invention.
Fig. 8(b) is a period latent simulated fault waveform obtained by changing ten sets of fault parameters of which the arc characteristic resistance varies between 0.005 Ω -0.015 Ω while keeping the arc characteristic voltage at 2kV and the arc time characteristic constant at 0.20ms according to the invention.
Fig. 8(c) is a multi-period latent simulated fault waveform obtained by changing ten sets of fault parameters of which the arc characteristic resistance varies between 0.005 Ω -0.015 Ω while keeping the arc characteristic voltage at 2kV and the arc time characteristic constant at 0.20ms according to the present invention.
Fig. 9(a) is a half-cycle latent simulated fault waveform obtained by changing ten sets of fault parameters with an arc time characteristic constant τ varying between 0.20ms and 0.40ms, while keeping the arc characteristic voltage at 2kV and the arc characteristic resistance at 0.005 Ω according to the present invention.
Fig. 9(b) is a period latent simulated fault waveform obtained by changing ten sets of fault parameters with the arc time characteristic constant τ varying between 0.20ms and 0.40ms, while keeping the arc characteristic voltage at 2kV and the arc characteristic resistance at 0.005 Ω according to the present invention.
Fig. 9(c) is a multi-period latent simulated fault waveform obtained by changing ten sets of fault parameters of which the arc time characteristic constant τ is changed between 0.20ms and 0.40ms, while keeping the arc characteristic voltage at 2kV and the arc characteristic resistance at 0.005 Ω.
In the figure: the spacing or dimensions between each other are exaggerated to show the location of the various parts, and the schematic is shown only schematically.
Wherein: 1. conductor, 2, insulating layer, 3, armor, 4, shell, 5, cable insulation, 6, core wire.
The specific implementation mode is as follows:
the present disclosure is further described with reference to the following drawings and examples.
It is to be understood that the following detailed description is exemplary and is intended to provide further explanation of the invention as claimed. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments according to the invention. As used herein, the singular forms "a", "an", and/or "the" are intended to include the plural forms as well, unless the invention expressly state otherwise, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof;
as introduced by the background, conventional protection and fault indicators in the prior art do not activate when a cable has a latent fault; in addition, the latent fault current waveform has high consistency with the initial waveform of other overcurrent (such as motor starting, load transient, permanent ground fault and the like), difficulty is brought to the prevention, identification and protection of the latent fault, and in order to solve the technical problems, the invention provides a method for simulating the latent fault of the medium-voltage distribution cable.
Example one
The embodiment of the invention introduces a method for simulating latent faults of a medium-voltage distribution cable, which comprises the following steps:
s1, establishing a mathematical equivalent model of the latent fault of the medium-voltage distribution cable based on the Kizilcay dynamic arc model;
s2, building a typical small-resistance medium-voltage cable power distribution system and a medium-voltage distribution cable latent fault equivalent simulation model in PSCAD electromagnetic simulation software based on a mathematical equivalent model of the medium-voltage distribution cable latent fault, and performing simulation on the medium-voltage distribution cable latent fault to obtain and observe an equivalent simulation waveform of the latent fault;
and S3, on the basis of the equivalent simulation model, researching and analyzing the influence of the main three parameters, namely arc characteristic voltage, characteristic resistance and time constant, on the fault characteristics, and realizing the simulation of the latent fault of the medium-voltage distribution cable.
Fig. 1 is a phase current waveform diagram of a latent fault of different degrees in the medium voltage distribution cable according to the present embodiment, wherein the process of deriving the latent fault model of the medium voltage distribution cable based on step S1 is as follows:
the mathematical expression of the Kizilcay dynamic arc model is as follows:
Figure RE-GDA0003510668800000081
wherein τ is a time characteristic constant; g is the static equivalent conductance of the arc; g is the arc transient conductance and the arc transient resistance RarcThe following quantitative relationships are satisfied:
Figure RE-GDA0003510668800000082
the static equivalent conductance G of the arc is the arc-follow current ifAnd a static arc voltage ust(t) correlation function:
Figure RE-GDA0003510668800000083
ust(t)＝u0+r0|if(t)|
wherein u is0Is the characteristic voltage of the arc, r0Is the arc characteristic resistance;
the complete formula for obtaining the Kizilcay dynamic arc model by arranging the formulas is as follows:
Figure RE-GDA0003510668800000084
it can be understood that in the process of establishing and obtaining the mathematical equivalent model of the latent faults of the medium-voltage distribution cable based on the Kizilcay dynamic arc model, as most of the latent faults of the medium-voltage distribution cable are generated by the insulation development of a water tree, an electric tree and the like, the latent faults can not be accurately simulated only by using the dynamic arc model, and therefore, the parts which are not subjected to arc discharge in a water tree and an electric tree channel before breakdown are equivalent to a constant resistor R0。
As shown in fig. 2, a constant resistance R is applied0In series with the Kizilcay dynamic arc model to better describe latent faults,the mathematical equivalent model of the latent fault of the medium-voltage distribution cable is regarded as the arc instantaneous resistance RarcConstant resistance R equivalent to defect channel0The expression is obtained by the series connection of (1):
uf(t)＝if(t)(R0+Rarc(t))
fig. 2 is a schematic diagram of an equivalent model of a latent fault of a medium voltage distribution cable comprising a cable insulation 5 and a core wire 6, wherein ufVoltage for a latent fault of the medium voltage distribution cablefIs the current of a latent fault of the medium voltage distribution cable.
In step S2, as shown in fig. 3, a small-resistance system medium-voltage cable distribution system is established in a PSCAD electromagnetic simulation software by using a Bergeron cable model, the end is connected with n cable feeders, a medium-voltage distribution cable latent fault equivalent simulation model is established on an EMTDC platform in the PSCAD electromagnetic simulation software according to the field actual fault distribution network cable parameters, and simulation is performed, in this embodiment, a power supply voltage of 110kV is reduced to 10kV by a step-down transformer, and n cable feeders are connected at the end of the distribution system as an example, and the cable parameters are shown in table 1 below:
Figure RE-GDA0003510668800000091
fig. 4 is a schematic structural diagram of a medium-voltage distribution cable, which includes a conductor 1, an insulating layer 2, an armor layer 3, and a housing 4 in sequence from inside to outside, and fig. 5 is a cable latent fault simulation model built by using a psadc/EMTD according to this embodiment.
The cable latent fault simulation model constructed by using PSACD/EMTD is operated. The simulation waveform of the latent fault of the medium-voltage distribution cable can be obtained as shown in fig. 6, and the subsequent researches on analysis, feature extraction, fault identification and the like of the latent fault of the medium-voltage distribution cable can be carried out according to the simulation waveform obtained by operating the simulation model.
As shown in FIGS. 7(a) -7 (c), the present embodiment is based on a simulation model and based on a single variable principle by changing the arc characteristic voltage u0Parameter (c), time characteristic constant tau, arc characteristic resistance r0The parameter setting can be used for obtaining the influence of the parameter setting on the latent fault characteristics of the medium-voltage distribution cable as follows: keeping the arc characteristic resistance constant at 0.005 Ω and the arc time characteristic constant at 0.20ms, with the arc characteristic voltage u0The parameters of the voltage transformer are continuously increased between 0.30 kV and 4kV, the voltage transformer is divided into ten groups of parameter conditions, simulation is respectively carried out under the ten groups of parameter conditions to obtain fault waveforms under different parameter conditions, and the fault waveforms are analyzed to obtain: the peak value of the arc current waveform is gradually reduced, so that the arc characteristic voltage u is considered to be0Is inversely related to the arc size;
as shown in fig. 8(a) -8 (c), based on the single variable principle, the arc characteristic voltage is kept at 2kV and the arc time characteristic constant is kept at 0.20ms, ten sets of fault parameters with the arc characteristic resistance varying between 0.005 Ω -0.015 Ω are changed, simulation is respectively performed under the conditions of the ten sets of parameters, fault waveforms under different parameters are obtained, the fault waveforms can be analyzed, and the waveforms of the arc are basically kept unchanged, so that the characteristic resistance r is considered to be constant0The impact on the arc model is not significant.
As shown in fig. 9(a) -9 (c), ten sets of fault parameters were varied with an arc time characteristic constant τ varying between 0.20ms and 0.40ms, with the arc characteristic voltage kept at 2kV and the arc characteristic resistance kept at 0.005 Ω. And respectively simulating under the condition of the ten groups of parameters to obtain fault waveforms under the condition of different parameters. Analyzing the fault waveform to obtain that as the time characteristic constant tau is increased from 0.20ms to 0.40ms, the peak value of the arc current waveform is gradually reduced in the first half period of the arc fault, and the waveform of the arc is basically kept unchanged afterwards, so that the time characteristic constant is considered to be in a negative correlation relation with the development trend of the first half period of the arc;
in this embodiment, the combination of different parameters is used to obtain the parameter combination condition with the best failure simulation effect of three main parameter settings: characteristic voltage u of arc02kV, time characteristic constant tau 0.2ms, fault characteristic resistance r0＝0.005Ω。
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (10)

1. A method of simulating a latent fault in a medium voltage distribution cable, comprising the steps of:
s1, establishing a mathematical equivalent model of the latent fault of the medium-voltage distribution cable based on the Kizilcay dynamic arc model;
s2, building a typical small-resistance medium-voltage cable power distribution system and a medium-voltage distribution cable latent fault equivalent simulation model in PSCAD electromagnetic simulation software based on a mathematical equivalent model of the medium-voltage distribution cable latent fault, and performing simulation on the medium-voltage distribution cable latent fault to obtain and observe an equivalent simulation waveform of the latent fault;
and S3, on the basis of the equivalent simulation model, researching and analyzing the influence of the main three parameters, namely arc characteristic voltage, characteristic resistance and time constant, on the fault characteristics, and realizing the simulation of the latent fault of the medium-voltage distribution cable.
2. A method for simulating latent faults in medium voltage distribution cables according to claim 1, characterized in that the mathematical expression of the Kizilcay dynamic arc model in step S1 is:
Figure RE-FDA0003510668790000011
wherein τ is a time characteristic constant; g is the static equivalent conductance of the arc; g is the arc transient conductance and the arc transient resistance RarcThe following quantitative relationships are satisfied:
Figure RE-FDA0003510668790000012
the static equivalent conductance G of the electric arc is the electric arc homeotropic current ifAnd a static arc voltage ust(t) correlation function:
Figure RE-FDA0003510668790000013
ust(t)＝u0+r0|if(t)|
wherein u is0Is the arc characteristic voltage; r is0Is the arc characteristic resistance;
the complete formula of the Kizilcay dynamic arc model obtained by processing the formula is as follows:
Figure RE-FDA0003510668790000021
3. the method for simulating the latent fault of the medium voltage distribution cable according to claim 2, wherein the mathematical equivalent model for the latent fault of the medium voltage distribution cable is established based on the Kizilcay dynamic arc model, and the parts of the water tree and the electric tree channels where the arc discharge does not occur are equivalent to the constant resistance R0。
4. A method for simulating a latent fault in a medium voltage distribution cable according to claim 3, characterized in that the constant resistance R is applied0Connected in series with the Kizilcay dynamic arc model, the mathematical equivalent model of the latent fault of the medium voltage distribution cable being regarded as the arc transient resistance RarcThe constant resistance R equivalent to the defective channel0Get the expression as:
uf(t)＝if(t)(R0+Rarc(t))
wherein u isfVoltage for a latent fault of the medium voltage distribution cablefFor the medium voltage distributionCurrent of latent fault of electric cable.
5. The method for simulating latent faults of medium voltage distribution cables according to claim 1, wherein in step S2, a low resistance system medium voltage cable distribution system is established in the PSCAD electromagnetic simulation software using a Bergeron cable model, and ends of the medium voltage cable distribution system are connected with n cable feeders.
6. The method for simulating the latent fault of the medium-voltage distribution cable according to claim 5, wherein an equivalent simulation model of the latent fault of the medium-voltage distribution cable is built on an EMTDC platform in the PSCAD electromagnetic simulation software according to the parameters of the field actual fault distribution cable, and simulation is performed.
7. A method of modelling a latent fault in a medium voltage distribution cable according to claim 6 wherein the effect of the arc characteristic voltage on the latent fault signature is derived by varying the arc characteristic voltage parameter settings on a single variable basis such that the arc characteristic voltage is inversely related to arc size.
8. A method for simulating a latent fault in a medium voltage distribution cable according to claim 6, characterized in that the influence of the time characteristic constant on the latent fault characteristic is derived by changing the parameter setting of the time characteristic constant on the basis of a univariate principle, in such a way that the time constant is only inversely related to the trend of the first half cycle of the arc.
9. A method of simulating a latent fault in a medium voltage distribution cable according to claim 6, characterized in that the arc characteristic resistance is derived to have little effect on the arc model by changing the arc characteristic resistance parameter settings on a univariate basis.
10. A method according to any one of claims 7 to 9, for simulating medium voltage distribution cable latencyThe fault method is characterized in that three main parameter settings are obtained by combining different parameters, and the parameter combination condition with the best fault simulation effect is as follows: the characteristic voltage u of the arc02kV, the time characteristic constant τ is 0.2ms, and the fault characteristic resistor r0＝0.005Ω。
CN202111424958.XA 2021-11-26 2021-11-26 Method for simulating latent fault of medium-voltage distribution cable Pending CN114647921A (en)

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