CN109975663A - Direct current arc fault detection method, device and system - Google Patents

Direct current arc fault detection method, device and system Download PDF

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Publication number
CN109975663A
CN109975663A CN201711464045.4A CN201711464045A CN109975663A CN 109975663 A CN109975663 A CN 109975663A CN 201711464045 A CN201711464045 A CN 201711464045A CN 109975663 A CN109975663 A CN 109975663A
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China
Prior art keywords
time period
difference
predetermined threshold
arc fault
current signal
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Chinese (zh)
Inventor
刘臻
陈维刚
杜峰
卓越
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Siemens AG
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Siemens AG
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    • GPHYSICS
    • G01MEASURING; TESTING
    • G01RMEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/12Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing
    • G01R31/1227Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing of components, parts or materials
    • G01R31/1263Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing of components, parts or materials of solid or fluid materials, e.g. insulation films, bulk material; of semiconductors or LV electronic components or parts; of cable, line or wire insulation
    • G01R31/1272Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing of components, parts or materials of solid or fluid materials, e.g. insulation films, bulk material; of semiconductors or LV electronic components or parts; of cable, line or wire insulation of cable, line or wire insulation, e.g. using partial discharge measurements

Abstract

Embodiment of the present invention discloses direct current arc fault detection method, device and system.Method includes: that the electric current high fdrequency component of DC current signal is detected in first time period;When the number of the electric current high fdrequency component detected in the first time period is greater than the first predetermined threshold, the electric current high fdrequency component of the detection DC current signal in second time period after the first time period;When the number of the electric current high fdrequency component detected in the second time period is greater than the second predetermined threshold, direct current arc fault is determined.Embodiment of the present invention is starting the arc stage and stabilization sub stage the threshold value counted for electric current high fdrequency component to be respectively set, and determine whether to detect arc fault solve the problems, such as to refuse when tripped tripping or should not unnecessary tripping when tripped to integrate based on the judgement result of two threshold values.

Description

Direct current arc fault detection method, device and system
Technical field
The present invention relates to arc fault (Arc Fault, AF) technical fields, more particularly to direct current arc fault detection side Method, device and system.
Background technique
Arc fault is that occur a kind of electric fault of non-human wish electric arc between conductor or between conductor and ground.According to Arc fault, can be divided into series arc faults, parallel arc fault, connect by electric arc and circuit connecting relation when arc fault occurs Ground arc fault and composite arc failure, etc..Once occur arc fault, due to arc current be generally in Thermal protection area it Outside, existing thermal circuit beraker is difficult to find this failure, can not occur protecting route when early stage is not also out of control in failure. Therefore, a kind of reliable method for detecting arc is needed to detect arc fault.
Currently, nearly all there is unnecessary trip problem in existing direct current arc fault testing product.Unnecessary jump Lock will lead to many disadvantages, such as power-off and additional maintenance.In addition, when overcoming unnecessary tripping, it is also necessary to guarantee when out It can trip when existing direct current arc fault.
Summary of the invention
Embodiment of the present invention proposes direct current arc fault detection methods, device and system.
The technical solution of embodiment of the present invention is as follows:
Direct current arc fault detection method, comprising:
The electric current high fdrequency component of DC current signal is detected in first time period;
When the number of the electric current high fdrequency component detected in the first time period is greater than the first predetermined threshold, in institute The electric current high fdrequency component of the detection DC current signal in second time period after stating first time period;
When the number of the electric current high fdrequency component detected in the second time period is greater than the second predetermined threshold, determine Direct current arc fault.
As it can be seen that embodiment of the present invention is starting the arc stage and stabilization sub stage to be respectively set and count for electric current high fdrequency component Independent threshold, and integrated based on the judgement result of the two independent thresholds and determine whether to detect arc fault solve and answer When tripped refusal tripping or should not when tripped unnecessary tripping the problem of.
In one embodiment, this method further include:
When the number of the electric current high fdrequency component detected in the first time period is less than or equal to the first predetermined threshold, Determine no direct current arc fault;Or
When the number of the electric current high fdrequency component detected in the second time period is less than or equal to the second predetermined threshold, Determine no direct current arc fault.
Therefore, when the number of the electric current high fdrequency component detected in first time period is less than or equal to the first predetermined threshold When, there is no the starting the arc for embodiment of the present invention identification, and thus determine that there is no direct current arc faults.Moreover, when the When the number of the electric current high fdrequency component detected in two periods is less than or equal to the second predetermined threshold, embodiment of the present invention identification There is no electric arc not enter into the stabilization sub stage, and thus determines that there is no direct current arc faults.
In one embodiment, this method further include:
DC current signal in the first time period is analyzed, point based on DC current signal in the first time period It analyses result and adjusts second predetermined threshold.
Therefore, embodiment of the present invention adaptively adjusts based on the analysis result of DC current signal in first time period Two predetermined thresholds, can further avoid refusing when tripped tripping or should not unnecessary tripping when tripped.
In one embodiment, DC current signal in the analysis first time period is based on the first time period The analysis result of interior DC current signal adjusts second predetermined threshold
Determine difference of the power spectral density of current signal in the first time period between detection cycle;
When the difference is lower than scheduled difference threshold, increase by second predetermined threshold.
In one embodiment, DC current signal in the analysis first time period is based on the first time period The analysis result of interior DC current signal adjusts second predetermined threshold
Determine difference of the power spectral density of DC current signal in the first time period between detection cycle;
When the difference is optionally greater than scheduled difference threshold, second predetermined threshold is reduced.
As it can be seen that embodiment of the present invention, which is realized, adaptively adjusts the second predetermined threshold, Ke Yizhun based on power spectral density Ambient noise and direct current arc fault are really distinguished, avoids that tripping should be refused when tripped or should not unnecessary tripping when tripped.
In one embodiment,
Difference of the power spectral density of DC current signal between detection cycle in the determination first time period Comprise determining that difference of the virtual value of current signal in the first time period between detection cycle.
Therefore, the virtual value expression that the present invention can use the current signal for being easy to determining is generally difficult to determining power spectrum Density reduces realization difficulty.
In one embodiment, DC current signal in the analysis first time period is based on the first time period The analysis result of interior DC current signal adjusts second predetermined threshold
Determine difference of the frequency domain character of DC current signal in the first time period between detection cycle;
When the difference is lower than scheduled difference threshold, increase by second predetermined threshold.
In one embodiment, DC current signal in the analysis first time period is based on the first time period The analysis result of interior DC current signal adjusts second predetermined threshold
Determine difference of the frequency domain character of DC current signal in the first time period between detection cycle;
When the difference is optionally greater than scheduled difference threshold, second predetermined threshold is reduced.
It, can be to avoid as it can be seen that embodiment of the present invention, which is realized, adaptively adjusts the second predetermined threshold based on frequency domain character Should refuse when tripped tripping or should not unnecessary tripping when tripped.
Direct current arc fault detection device, comprising:
First detection module detects the electric current high fdrequency component of DC current signal in first time period;
Second detection module, when the high frequency division of electric current that the first detection module detects in the first time period When the number of amount is greater than the first predetermined threshold, the detection DC current letter in second time period after the first time period Number electric current high fdrequency component;
Breakdown judge module, when the high frequency division of electric current that second detection module detects in the second time period When the number of amount is greater than the second predetermined threshold, direct current arc fault is determined.
As it can be seen that embodiment of the present invention is starting the arc stage and stabilization sub stage to be respectively set and count for electric current high fdrequency component Independent threshold, and integrated based on the judgement result of the two independent thresholds and determine whether to detect arc fault solve and answer When tripped refusal tripping or should not when tripped unnecessary tripping the problem of.
In one embodiment,
The breakdown judge module, when the high frequency division of electric current that first detection module detects in the first time period When the number of amount is less than or equal to the first predetermined threshold, no direct current arc fault is determined;Or
It is less than or equal to when the number for the electric current high fdrequency component that the second detection module detects in the second time period When the second predetermined threshold, no direct current arc fault is determined.
Therefore, when the number of the electric current high fdrequency component detected in first time period is less than or equal to the first predetermined threshold When, there is no the starting the arc for embodiment of the present invention identification, and thus determine that there is no direct current arc faults.Moreover, when the When the number of the electric current high fdrequency component detected in two periods is less than or equal to the second predetermined threshold, embodiment of the present invention identification There is no electric arc not enter into the stabilization sub stage, and thus determines that there is no direct current arc faults.
In one embodiment, further includes:
Threshold adjustment module analyzes DC current signal in the first time period, based in the first time period The analysis result of DC current signal adjusts second predetermined threshold.
Therefore, embodiment of the present invention adaptively adjusts based on the analysis result of DC current signal in first time period Two predetermined thresholds, can further avoid refusing when tripped tripping or should not unnecessary tripping when tripped.
In one embodiment,
The threshold adjustment module determines that the power spectral density of DC current signal in the first time period is detecting Difference between period increases by second predetermined threshold when the difference is lower than scheduled difference threshold.
In one embodiment,
The threshold adjustment module determines that the power spectral density of DC current signal in the first time period is detecting Difference between period reduces by second predetermined threshold when the difference is optionally greater than scheduled difference threshold.
As it can be seen that embodiment of the present invention, which is realized, adaptively adjusts the second predetermined threshold, Ke Yizhun based on power spectral density Ambient noise and direct current arc fault are really distinguished, avoids that tripping should be refused when tripped or should not unnecessary tripping when tripped.
In one embodiment,
The threshold adjustment module determines the frequency domain character of DC current signal in the first time period in detection week Difference between phase increases by second predetermined threshold when the difference is lower than scheduled difference threshold.
In one embodiment, the threshold adjustment module determines DC current signal in the first time period Difference of the frequency domain character between detection cycle reduce described the when the difference is optionally greater than scheduled difference threshold Two predetermined thresholds.
It, can be to avoid as it can be seen that embodiment of the present invention, which is realized, adaptively adjusts the second predetermined threshold based on frequency domain character Should refuse when tripped tripping or should not unnecessary tripping when tripped.
Direct current arc fault detection system, comprising:
Current sensor detects DC current signal;
Analog front end processing device extracts electric current high fdrequency component from the DC current signal;
The electric current high fdrequency component is converted to number format by analog-digital commutator;
Direct current arc fault detection device detects the electric current high fdrequency component of the number format in first time period, When the number of the electric current high fdrequency component detected in the first time period is greater than the first predetermined threshold, at described first Between in second time period after section the detection DC current signal electric current high fdrequency component, examined when in the second time period When the number of the electric current high fdrequency component measured is greater than the second predetermined threshold, direct current arc fault is determined.
Embodiment of the present invention is starting the arc stage and stabilization sub stage the independence counted for electric current high fdrequency component to be respectively set Threshold value, and integrated based on the judgement result of the two independent thresholds and determine whether to detect arc fault, solving should jump When lock refusal tripping or should not when tripped unnecessary tripping the problem of.
In one embodiment,
The direct current arc fault detection device, is also used to analyze DC current signal in the first time period, is based on The analysis result of DC current signal adjusts second predetermined threshold in the first time period;
Wherein DC current signal in the analysis first time period, based on DC current signal in the first time period Analysis result adjust second predetermined threshold and comprise determining that the power spectral density of current signal in the first time period exists Difference between detection cycle increases by second predetermined threshold when the difference is lower than scheduled difference threshold, when described Difference reduces by second predetermined threshold when being optionally greater than scheduled difference threshold;Or, determining direct current in the first time period Difference of the frequency domain character of current signal between detection cycle, when the difference is lower than scheduled difference threshold described in increase Second predetermined threshold reduces by second predetermined threshold when the difference is optionally greater than scheduled difference threshold.
Therefore, embodiment of the present invention also achieves that adaptively to adjust second based on frequency domain character and power spectrum characteristic predetermined Threshold value can accurately distinguish ambient noise and direct current arc fault, avoid refusing when tripped tripping or should not be when tripped Unnecessary tripping.
Computer readable storage medium is stored thereon with computer program, when the computer program is executed by processor The step of realizing as above described in any item direct current arc fault detection methods.
Detailed description of the invention
Fig. 1 is the schematic diagram stage by stage of electric arc.
Fig. 2 is high fdrequency component schematic diagram of the electric arc in different phase.
Fig. 3 is the flow chart according to the direct current arc fault detection method of embodiment of the present invention.
Fig. 4 is ambient noise and its power spectral density (power spectral density, PSD) and root mean square (Root Meam Square, RMS) value schematic diagram.
Fig. 5 is arc signal and its schematic diagram of PSD and RMS value.
Fig. 6 is the window enumeration method flow diagram according to embodiment of the present invention in the arc Starting Arc stage.
Fig. 7 is the window enumeration method flow diagram according to embodiment of the present invention in the arc stability stage.
Fig. 8 is the direct current arc fault detection method flow chart that dual thresholds are used according to embodiment of the present invention.
Fig. 9 is the ambient noise schematic diagram according to the embodiment of the present invention inverter startup stage, and wherein threshold value is without adaptive It should adjust.
Figure 10 is the ambient noise schematic diagram according to the embodiment of the present invention inverter startup stage, and wherein threshold value has adaptive It should adjust.
Figure 11 is the schematic diagram that the arc signal of ambient noise is mixed with according to embodiment of the present invention inverter, wherein threshold Value has adaptive adjustment.
Figure 12 is the structure chart according to embodiment of the present invention direct current arc fault detection device.
Figure 13 is the structure chart according to embodiment of the present invention direct current arc fault detection system.
Wherein, appended drawing reference is as follows:
Specific embodiment
In order to which technical solution of the present invention and advantage is more clearly understood, below in conjunction with drawings and the embodiments, to this Invention is further elaborated.It should be appreciated that the specific embodiments described herein are only used to illustrative illustrate originally Invention, is not intended to limit the scope of protection of the present invention.
It is succinct and intuitive in order to what is described, hereafter by describing several representative embodiments come to side of the invention Case is illustrated.A large amount of details is only used for helping to understand the solution of the present invention in embodiment.However, it will be apparent that of the invention Technical solution can be not limited to these details when realizing.In order to avoid unnecessarily having obscured the solution of the present invention, Yi Xieshi It applies mode not described meticulously, but only gives frame.Hereinafter, " comprising " refers to " including but not limited to ", " root According to ... " refer to " according at least to ..., but be not limited to according only to ... ".Due to the speech habits of Chinese, hereinafter without spy When not pointing out the quantity of an ingredient, it is meant that the ingredient is either one or more, or can be regarded as at least one.
Applicant researchs and analyses electric arc, it is found that the time-continuing process of electric arc includes two stages, respectively starting the arc rank Section and stabilization sub stage.The starting the arc stage is the unstable stage.In the starting the arc stage, pass through the electricity of normal non-conductive medium (such as air) The raw plasma of miscarriage.If can be with continuous discharge, electric arc be from the starting the arc transition stage to stabilization sub stage.
Fig. 1 is the schematic diagram stage by stage of electric arc.In Fig. 1, horizontal axis is the time, and the longitudinal axis is current value.As it can be seen that in starting the arc rank Section 11, current value fluctuating range is larger, and unstable.After entering the stabilization sub stage 12, current value becomes relatively stable.
Fig. 2 is high fdrequency component schematic diagram of the electric arc in different phase.In Fig. 2, horizontal axis is frequency, and the longitudinal axis is current value. The upper area of Fig. 2 is the starting the arc stage 11, and the lower area of Fig. 2 is the stabilization sub stage 12.The frequency spectrum shown in Fig. 2 can be seen that The current value in arc stage 11 is apparently higher than the current value of stabilization sub stage 12.
After detecting arc fault, it usually needs execute trip operation to protect electrical equipment.It is found by the applicant that: if According only to electric arc a stage and the threshold value for detecting arc fault is set, then may cause should refuse to trip when tripped Or should not when tripped unnecessary tripping (i.e. mistrip) the technical issues of.For example, being examined if being provided with higher arc fault Threshold value is surveyed, then may refuse tripping when there is direct current arc fault;If being provided with lower arc fault detection threshold value, It may mistrip when there is no direct current arc fault.
For solve the problems, such as to refuse when tripped tripping or should not unnecessary tripping when tripped, the application be starting the arc rank The threshold value counted for electric current high fdrequency component is respectively set in section and stabilization sub stage, and is integrated based on the judgement result of two threshold values Determine whether to detect arc fault.
Fig. 3 is the flow chart according to the direct current arc fault detection method of embodiment of the present invention.
As shown in figure 3, this method comprises:
Step 301: the electric current high fdrequency component of DC current signal is detected in first time period.
Step 302: when the number of the electric current high fdrequency component detected in first time period is greater than the first predetermined threshold, The electric current high fdrequency component of DC current signal is detected in second time period after first time period.
Step 303: when the number of the electric current high fdrequency component detected in second time period is greater than the second predetermined threshold, Determine direct current arc fault.
Wherein, first time period corresponds to the starting the arc stage of electric arc, and second time period corresponds to the stabilization sub stage of electric arc.And And the judgment basis of electric current high fdrequency component is judged whether it is in first time period and judges whether it is electricity in second time period The judgment basis for flowing high fdrequency component can be common judgment basis or different judgment basis.
Preferably, the judgment basis that electric current high fdrequency component is judged whether it is in first time period is higher than in second time period Inside judge whether it is the judgment basis of electric current high fdrequency component.Such as, it is assumed that electric current high frequency is judged whether it is in first time period The judgment basis of component is 10 milliamperes (mA), i.e., regards as electric current high frequency when the current component in first time period is higher than 10mA Component.Judge moreover, the judgment basis for judging whether it is electric current high fdrequency component in second time period is less than in first time period Whether be electric current high fdrequency component judgment basis, i.e., less than 10 milliamperes (mA), for example electric current is judged whether it is in second time period The judgment basis of high fdrequency component is 8mA, i.e., regards as the high frequency division of electric current when the current component in second time period is higher than 8mA Amount.
In embodiments of the present invention, when the number of the electric current high fdrequency component detected in first time period is greater than first When predetermined threshold, and remarkable identification has been detected by direct current arc fault, but further detects in second time period straight The electric current high fdrequency component of current signal is flowed, and when the number of the electric current high fdrequency component detected in second time period is greater than second When predetermined threshold, direct current arc fault is just determined.
As it can be seen that embodiment of the present invention uses the direct current arc fault testing mechanism of dual thresholds, due to the two threshold values Two arcing phases with different high fdrequency components are respectively suitable for, therefore help avoid refusing when tripped tripping or not Answer unnecessary tripping when tripped.
In one embodiment, this method further include: when the electric current high fdrequency component detected in first time period When number is less than or equal to the first predetermined threshold, no direct current arc fault is determined.
Herein, when the number of the electric current high fdrequency component detected in first time period is less than or equal to the first predetermined threshold When, it can be assumed that there is no the starting the arc, therefore, it is determined that there is no direct current arc faults.
In one embodiment, this method further include: when the electric current high fdrequency component detected in second time period When number is less than or equal to the second predetermined threshold, no direct current arc fault is determined.
Herein, when the number of the electric current high fdrequency component detected in second time period is less than or equal to the second predetermined threshold When, it can be assumed that no electric arc does not enter into the stabilization sub stage, therefore, it is determined that there is no direct current arc faults.
Applicant further found that if the analysis result based on DC current signal in first time period adaptively adjusts second Predetermined threshold, can further avoid refusing when tripped tripping or should not unnecessary tripping when tripped.
In one embodiment, this method further includes step 304: DC current signal in analysis first time period, base The second predetermined threshold is adjusted in the analysis result of DC current signal in first time period.Wherein it is possible to have after step 303 Body implementation steps 304, can also between step 302 and step 303 specific implementation step 304.
Below to how the analysis result based on DC current signal in first time period and adjust the second predetermined threshold into Row illustrates.
The main reason for high frequency background noise of current signal is unnecessary tripping.Its main feature is that working as no arc fault When, the power spectral density (power spectral density, PSD) of ambient noise is almost the same in each period.Based on Machine signal analysis and processing is theoretical, and PSD is the energy of per unit frequency.PSD is stochastic variable (E [x2(t)] and RMS value it is flat Side) mean-square value measurement, wherein E [x2It (t)] is the area defined by PSD-f curve.
Situation 1: the stationary random process for being zero for average value:
According to Paasche Wa Er (Parseval) theorem, the integrated square of quadractically integrable function becomes equal to its fast Flourier Change the quadratic sum of (FFT) coefficient X (w).This shows to be equal to the signal energy calculated in a frequency domain in the signal energy of time-domain calculation. Moreover, the square value of RMS can represent PSD according to the definition of PSD.
Situation 2: for the stationary random process of Non-zero Mean:
Based on wiener-Qin Qin (Wiener-Khinchin) theorem, PSD can pass through the Fourier transformation of auto-correlation function It provides.
If τ is equal to 0, auto-correlation function is equal to signal energy,Wherein RxIt (0) is auto-correlation The maximum value of function.
So,Therefore the square value of RMS indicates the integral of PSD-f.
In short, random process stable for one, RMS value can represent PSD.Background as stationary random process is made an uproar The PSD of sound can be indicated with the RMS value of current signal.
Fig. 4 is the schematic diagram of ambient noise and its RMS value, and wherein RMS value is current effective value.In Fig. 4, topmost Coordinate system horizontal axis be the time, the longitudinal axis is ambient noise;The horizontal axis of middle coordinate system is time, longitudinal axis PSD;It is nethermost The horizontal axis of coordinate system is the time, and the longitudinal axis is RMS value.The detection window of each detection cycle is 5ms.From fig. 4, it can be seen that in each inspection It is all almost the same to survey PSD in window, and the RMS value of electric current is almost the same.That is, in the case where no arc fault When ambient noise (only have), the difference of the current RMS value of continuous two detection windows is close to zero.
Fig. 5 is arc signal and its schematic diagram of PSD and RMS value.In Fig. 5, when the horizontal axis of uppermost coordinate system is Between, the longitudinal axis is arc signal;The horizontal axis of middle coordinate system is time, longitudinal axis PSD;When the horizontal axis of nethermost coordinate system is Between, the longitudinal axis is RMS value.The detection window of each detection cycle is 5ms.As seen from Figure 5, when arc fault occurs, Mei Gejian The PSD for surveying window is different, and the RMS value of time domain is not also identical.That is, (i.e. in the case where arc fault occurs Not only have powerful connections noise when), the difference of the current RMS value of continuous two detection windows is not zero.
Based on above-mentioned analysis, the RMS value of electric current can be used as second that boundary condition comes in adaptively set-up procedure 303 Predetermined threshold.
If the difference of the RMS value between continuous detection window is zero or close to zero, which reflects arc faults Possibility is smaller, therefore can increase by the second predetermined threshold to avoid unnecessary tripping.If between continuous detection window RMS value it is widely different, a possibility that illustrating arc fault, is very big, then should reduce the second predetermined threshold to avoid should Refuse tripping when tripping.
In addition, frequency-domain analysis result also can be used as the boundary condition of the second predetermined threshold of adjustment.If the frequency in starting the arc stage A possibility that domain characteristic is not obvious, and which reflects arc faults is smaller, then should increase by the second predetermined threshold to avoid unnecessary Tripping.If a possibility that frequency domain characteristic in starting the arc stage is clearly, shows arc fault is very big, then should be reduced Two predetermined thresholds to avoid should refuse to trip when tripped.
Therefore, in one embodiment, DC current signal in first time period is analyzed, based on straight in first time period The analysis result of stream current signal adjusts the second predetermined threshold and comprises determining that the PSD of current signal in first time period is being detected Difference between period;When difference is lower than scheduled difference threshold, increase by the second predetermined threshold.
Preferably, difference of the RMS value of current signal in first time period between detection cycle is determined;When difference is lower than When scheduled difference threshold, increase by the second predetermined threshold.
Preferably, difference of the RMS value of current signal in first time period between detection cycle is determined, when difference is higher than When equal to scheduled difference threshold, the second predetermined threshold is reduced.
Wherein, the above-mentioned predetermined difference value threshold value for RMS value may be embodied as zero.Those skilled in the art will be appreciated that Arrive, the above-mentioned predetermined difference value threshold value for RMS value can also be embodied as other empirical values, embodiment of the present invention to this and it is unlimited It is fixed.
Indicate that PSD is described in detail embodiment of the present invention as example using RMS value above, those skilled in the art can With, it is realized that this representation is only the specific example of embodiment of the present invention, embodiment of the present invention is to this and is not limited.
In one embodiment, DC current signal in first time period is analyzed, based on direct current in first time period The analysis result of stream signal adjusts the second predetermined threshold and comprises determining that the frequency domain character of DC current signal in first time period exists Difference between detection cycle;When difference is lower than scheduled difference threshold, increase by the second predetermined threshold;When difference is optionally greater than When scheduled difference threshold, the second predetermined threshold is reduced.
Similarly, the above-mentioned predetermined difference value threshold value for frequency domain character may be embodied as zero.Those skilled in the art can be with , it is realized that the above-mentioned predetermined difference value threshold value for frequency domain character can also be embodied as other empirical values, embodiment of the present invention pair This is simultaneously not limited.
In embodiments of the present invention, the specific value of the second predetermined threshold can be directly adjusted, it can also be by adjusting The judgment basis that electric current high fdrequency component is judged whether it is in second time period carrys out the second predetermined threshold of Indirect method.
Below to by adjusting whether be the judgment basis of electric current high fdrequency component and the direct-current arc detection method realized into Row detailed description.
Fig. 6 is the window enumeration method flow diagram according to embodiment of the present invention in the arc Starting Arc stage.Wherein, multiple The individual window of 5ms executes processing to current signal.Fast Fourier transform (the Fast for being 200Hz for frequency resolution Fourier Transformation, FFT), in each 5ms window, there are 350 frequency points from 30KHz to 100KHz.Each window The high frequency characteristics of mouth can be indicated by count value, wherein successively judging according to from the sequence of the 1st frequency point to the 350th frequency point: If the amplitude of any frequency point (In) is more than the first predetermined amplitude threshold value (for example, first predetermined amplitude threshold value is embodied as no electricity When arc failure from 30KHz to 100KHz Frequency point amplitude average value), then count is incremented 0, otherwise counts and subtracts 2;Then, it obtains each The total count value of a window.
As shown in fig. 6, this method comprises:
Step 601: counting starts.
Step 602: judge whether bin magnitudes are greater than the first predetermined amplitude threshold value, if it is then follow the steps 603 and its Subsequent step, it is no to then follow the steps 604 and its subsequent step.
Step 603: count is incremented 0, and executes step 605.
Step 604: counting subtracts 2, and executes step 605.
Step 605: judging whether frequency point number reaches 350, if so, thening follow the steps 606, otherwise return to step 602。
Step 606: counting terminates.
After above-mentioned process, final count value can be with the number of the electric current high fdrequency component of the quantization means windows.
Can determine whether that starting the arc rank occurs based on process shown in the first predetermined amplitude threshold value, the first predetermined threshold and Fig. 6 Section.For example, setting first time period includes 5 continuous windows.The electricity of each continuous window can be determined based on process shown in Fig. 6 Flow the number of high fdrequency component.Presetting window of the count number greater than 1750 is 1 starting the arc window, and the first predetermined threshold is arranged Value is 3, i.e., assert when having in this 5 continuous windows greater than 3 starting the arc windows and the starting the arc stage occurs.
Fig. 7 is the window enumeration method flow diagram according to embodiment of the present invention in the arc stability stage.Wherein, multiple The individual window of 5ms executes processing to current signal.The FFT for being 200Hz for frequency resolution, in every 5ms window, from 30KHz to 100KHz has 350 frequency points.The high frequency characteristics of each window can indicate by count value, wherein according to from the 1st frequency O'clock successively judge to the sequence of the 350th frequency point: if the amplitude of any frequency point (In) is more than the second predetermined amplitude threshold value, counting Otherwise number plus 10 counts and subtracts 2;Then, the total count value of each window is obtained.When the second predetermined amplitude threshold value is nonadjustable When fixed value, the second predetermined amplitude threshold value is preferably shorter than the first predetermined amplitude threshold value.When the second predetermined amplitude threshold value is that can adjust When whole changing value, the initial value of the second predetermined amplitude threshold value is preferably shorter than the first predetermined amplitude threshold value.
As shown in fig. 7, this method comprises:
Step 701: counting starts.
Step 702: judge whether bin magnitudes are greater than the second predetermined amplitude threshold value, if it is then follow the steps 703 and its Subsequent step, it is no to then follow the steps 704 and its subsequent step.
Step 703: count is incremented 0, and executes step 705.
Step 704: counting subtracts 2, and executes step 705.
Step 705: judging whether frequency point number reaches 350, if so, thening follow the steps 706, otherwise return to step 702。
Step 706: counting terminates.
After above-mentioned process, obtained final count value can be with the number of the electric current high fdrequency component of the quantization means windows Mesh.
It can determine whether to stablize rank based on process shown in the second predetermined amplitude threshold value, the second predetermined threshold and Fig. 7 Section.For example, setting second time period includes 20 continuous windows.Each continuous window can be determined based on process shown in Fig. 7 The number of electric current high fdrequency component.Presetting window of the count number greater than 1750 is 1 stability window, and it is predetermined to be arranged second Threshold value is 15, i.e., assert when having in this 20 continuous windows greater than 15 starting the arc windows and the stabilization sub stage occurs.
Fig. 8 is the direct current arc fault detection method flow chart that dual thresholds are used according to embodiment of the present invention.In Fig. 8 In, continuous 5 windows are starting the arc detection-phase.If moreover, setting has more than the meter of 3 windows in starting the arc detection-phase Number is more than predetermined number (such as 1750), then detects the starting the arc stage, and starts to detect the arc stability stage.In stable detection rank Section, can be judged whether according to RMS value discrepancy adjustment adjust the second predetermined threshold (wherein keep electric current high fdrequency component judgement according to According to constant).Alternatively, can judge whether that the judgment basis for adjusting electric current high fdrequency component (is wherein kept according to RMS value discrepancy adjustment Second predetermined threshold is constant).Such as, it is assumed that the judgment basis of the electric current high fdrequency component in the arc stability stage is constant, continuous 20 windows in, if it exceeds the counting of 15 windows be more than predetermined number (such as 1750), then detect arc fault.Figure 8 also describe the calculating process of the difference of the RMS value of the boundary condition as adjustment second threshold.
As shown in figure 8, this method comprises:
Step 800: starting.
Step 801: starting arc Starting Arc stage timing.
Step 802:FFT window starts to detect.
Step 803: counting is executed to all frequency points of FFT window based on the first predetermined amplitude threshold value (for example, 10mA), In be greater than the frequency point of the first predetermined amplitude threshold value count is incremented 0, the frequency point counting no more than the first predetermined amplitude threshold value subtracts 2.
Step 804: judging whether the count value of the FFT window is greater than predetermined number (for example, 1750), if it is executing step Rapid 805 and its subsequent step, it is no to then follow the steps 806 and its subsequent step.
Step 805: starting the arc window enumeration number (A) plus one.
Step 806: judging whether scheduled five windows are all counted, if so, thening follow the steps 807 and its subsequent step Suddenly, 802 and its subsequent step are otherwise returned to step.
Step 807: arc Starting Arc stage timer expiration.
Step 808: judging whether starting the arc window enumeration number is greater than preset first predetermined threshold (for example, 3).Such as Fruit is to then follow the steps 809 and its subsequent step, otherwise executes and returns to step 801 and its subsequent step.
Step 809: difference of the PSD of the current signal during calculating arc Starting Arc stage timing between detection cycle, When difference is lower than scheduled difference threshold (for example, zero), increase by the second predetermined threshold, when difference is optionally greater than scheduled difference When threshold value (for example, zero), the second predetermined threshold is reduced;Or, calculating the frequency domain of the current signal during the timing of arc Starting Arc stage Difference of the feature between detection cycle increases by the second predetermined threshold when difference is lower than scheduled difference threshold (for example, zero) Value reduces the second predetermined threshold when difference is optionally greater than scheduled difference threshold (for example, zero).
Step 810: starting arc stability stage timing.
Step 811:FFT window starts to detect.
Step 812: counting is executed to all frequency points of FFT window based on the second predetermined amplitude threshold value (for example, 8mA), In be greater than the frequency point of the second predetermined amplitude threshold value count is incremented 0, the frequency point counting no more than the second predetermined amplitude threshold value subtracts 2.
Step 813: judging whether the count value of the FFT window is greater than predetermined number (for example, 1750), if it is executing step Rapid 814 and its subsequent step, it is no to then follow the steps 815 and its subsequent step
Step 814: stability window number (B) plus one.
Step 815: judging whether scheduled 20 windows are all counted, if so, thening follow the steps 816 and its subsequent Otherwise step returns to step 811 and its subsequent step.
Step 816: arc stability stage timer expiration.
Step 817: whether judge stability window number is greater than the second predetermined threshold for being adjusted, and wherein this is second predetermined Threshold value is adjusted since initial value in step 809, if so, thening follow the steps 818 and its subsequent step, is otherwise executed and is returned Receipt row step 801 and its subsequent step.
Step 818: confirmation detects direct current arc fault.
In process shown in Fig. 8, the PSD based on the current signal during the timing of arc Starting Arc stage is between detection cycle Difference between detection cycle of difference or frequency domain character directly adjust the specific value of the second predetermined threshold.Optionally, also It can not directly adjust the second predetermined threshold, but by adjusting judging whether it is electric current high fdrequency component in the arc stability stage Judgment basis carrys out the second predetermined threshold of Indirect method.
For example, difference or frequency domain of the PSD of the current signal during the timing of arc Starting Arc stage between detection cycle When difference of the feature between detection cycle is smaller, does not increase by the second predetermined threshold directly, but increase by the second predetermined amplitude threshold Value (for example, being adjusted to 10mA from 8mA) is to reduce stability window number, to obtain same as directly increasing by the second predetermined threshold Effect.
For another example, difference or frequency of the PSD of the current signal during the timing of arc Starting Arc stage between detection cycle When difference of the characteristic of field between detection cycle is larger, the second predetermined threshold is not reduced directly, but reduces the second predetermined amplitude Threshold value (for example, being adjusted to 6mA from 8mA) is to increase stability window number, to obtain same with directly the second predetermined threshold of reduction The effect of sample.
Fig. 9 is the ambient noise schematic diagram according to the embodiment of the present invention inverter startup stage, and wherein threshold value is without adaptive It should adjust.
In Fig. 9, the horizontal axis of uppermost coordinate system is the time, and the longitudinal axis is high frequency background noise;The cross of middle coordinate system Axis is the time, and the longitudinal axis is high fdrequency component count value;The horizontal axis of nethermost coordinate system is the time, and the longitudinal axis is arc fault mark, It is wherein identified as 0 expression and does not detect arc fault, be identified as 1 expression and detect arc fault.As shown in figure 9, inverter High frequency background noise handled using dual threshold, adjusted without threshold adaptive.Judge whether it is in first time period The judgment basis (th1) of electric current high fdrequency component is 10mA.In continuous 5 windows, the counting for having more than 3 windows is more than 1750.Then, start arc stability detection-phase, the judgment basis of electric current high fdrequency component is judged whether it is in second time period It (th2) is 0.8*th1.Due to judge whether it is in high frequency background and second time period electric current high fdrequency component judgment basis it is low Level, counting sharply increase.More than 15 windows are shown in continuous 20 windows, quantity has been more than 1750.So Afterwards, undesirable tripping is caused by high-frequency noise.
Figure 10 is the ambient noise schematic diagram according to the embodiment of the present invention inverter startup stage, and wherein threshold value has adaptive It should adjust.
In Figure 10, the horizontal axis of uppermost coordinate system is the time, and the longitudinal axis is high frequency background noise;According to suitable from top to bottom The horizontal axis of the deputy coordinate system of sequence is the time, and the longitudinal axis is high fdrequency component count value;According to the seat of sequence third position from top to bottom The horizontal axis of mark system is the time, and the longitudinal axis is the difference of RMS value;The horizontal axis of nethermost coordinate system is the time, and the longitudinal axis is arc fault Mark, wherein being identified as 0 expression does not detect arc fault, is identified as 1 expression and detects arc fault.As shown in Figure 10, The identical high-frequency noise of inverter is handled using the adaptive adjustment mode of dual thresholds.Due to RMS value in first time period Differential nearly zero, the judgment basis (th2) that electric current high fdrequency component is judged whether it is in second time period increases to 1.1*th1, The second predetermined amplitude threshold value is increased, that is, equivalent to increase the second predetermined threshold.Therefore, even if high-frequency noise causes The detection starting the arc of mistake there will not be further mistake and determine, i.e., in continuous 20 windows, no more than 15 windows The counting of mouth is more than 1750.Therefore will not cause to trip by unnecessary high-frequency noise.
Figure 11 is the schematic diagram that the arc signal of ambient noise is mixed with according to embodiment of the present invention inverter, wherein threshold Value has adaptive adjustment.In Figure 11, the horizontal axis of uppermost coordinate system is the time, and the longitudinal axis is high frequency background noise;According to from The horizontal axis of the deputy coordinate system of top to bottm sequence is the time, and the longitudinal axis is high fdrequency component count value;According to sequence the from top to bottom The horizontal axis of three coordinate systems is the time, and the longitudinal axis is the difference of RMS value;The horizontal axis of nethermost coordinate system is the time, and the longitudinal axis is Arc fault mark, wherein being identified as 0 expression does not detect arc fault, is identified as 1 expression and detects arc fault.Such as figure Shown in 11, the high-frequency signal mixed using two threshold process with arc signal and inverter ambient noise, wherein threshold value is adaptive It should adjust.The judgment basis (th1) that electric current high fdrequency component is judged whether it is in first time period is 10mA.When arc fault goes out Now, RMS value differs greatly, and judgment basis (th2) adjustment of electric current high fdrequency component is judged whether it is in second time period For 0.8*th1, that is, the second predetermined amplitude threshold value is reduced, being equivalent to reduces the second predetermined threshold.In the starting the arc stage, continuously In 5 windows, having 3 or more window enumerations is more than 1750.Stablize segmental arc, there are 15 or more in continuous 20 windows Window enumeration be more than 1750.It is then possible to detect arc fault, and trip operation is correctly executed based on arc fault.Cause This, will not refuse to trip when real arc fault occurs.
Based on foregoing description, the invention also provides direct current arc fault detection devices.
Figure 12 is the structure chart according to embodiment of the present invention direct current arc fault detection device.
As shown in figure 12, direct current arc fault detection device 1200 includes:
First detection module 1201 detects the electric current high fdrequency component of DC current signal in first time period;
Second detection module 1202, when the high frequency division of electric current that first detection module 1201 detects in first time period When the number of amount is greater than the first predetermined threshold, the electric current of DC current signal is detected in the second time period after first time period High fdrequency component;
Breakdown judge module 1203, when the high frequency division of electric current that the second detection module 1202 detects in second time period When the number of amount is greater than the second predetermined threshold, direct current arc fault is determined.
In one embodiment: breakdown judge module 1203, when first detection module 1201 is in first time period When the number of the electric current high fdrequency component detected is less than or equal to the first predetermined threshold, no direct current arc fault is determined;Or
It is less than or equal to when the number for the electric current high fdrequency component that the second detection module 1202 detects in second time period When the second predetermined threshold, no direct current arc fault is determined.
In one embodiment: further include:
Threshold adjustment module 1204 analyzes DC current signal in first time period, based on direct current in first time period The analysis result of current signal adjusts the second predetermined threshold.
In one embodiment: threshold adjustment module 1204 determines the PSD of DC current signal in first time period Difference between detection cycle increases by the second predetermined threshold when difference is lower than scheduled difference threshold.
In one embodiment: threshold adjustment module 1204 determines the PSD of DC current signal in first time period Difference between detection cycle reduces the second predetermined threshold when difference is optionally greater than scheduled difference threshold.
In one embodiment: threshold adjustment module 1204 determines the frequency of DC current signal in first time period Difference of the characteristic of field between detection cycle increases by the second predetermined threshold when difference is lower than scheduled difference threshold.
In one embodiment: threshold adjustment module 1204 determines the frequency of DC current signal in first time period Difference of the characteristic of field between detection cycle reduces the second predetermined threshold when difference is optionally greater than scheduled difference threshold.
Based on above-mentioned analysis, embodiment of the present invention also proposed a kind of direct current arc fault detection system.
Figure 13 is the structure chart according to embodiment of the present invention direct current arc fault detection system.
As shown in figure 13, direct current arc fault detection system 1300, comprising:
Current sensor 1301 detects DC current signal 50;
Analog front end processing device 1302 extracts electric current high fdrequency component from DC current signal 50;
Electric current high fdrequency component is converted to number format by analog-digital commutator 1303;
Direct current arc fault detection device 1304 detects the electric current high fdrequency component of number format in first time period, When the number of the electric current high fdrequency component detected in first time period is greater than the first predetermined threshold, after first time period The electric current high fdrequency component of detection DC current signal in second time period, when the high frequency division of the electric current detected in second time period When the number of amount is greater than the second predetermined threshold, direct current arc fault is determined.
Preferably, analog front end processing device 1302 extracts the electric current of 30-100KHz bandwidth from DC current signal 50 High fdrequency component.
In one embodiment, direct current arc fault detection device 1304 is also used to analyze direct current in first time period Current signal, the analysis result based on DC current signal in first time period adjust the second predetermined threshold.
Specifically, as shown in the top half of 1304 block diagram of direct current arc fault detection device: in FFT unit 1305, Difference of the frequency domain character of DC current signal in first time period between detection cycle is determined based on fft algorithm.Then, exist In threshold adjustment unit 1307, increase by the second predetermined threshold when difference is lower than scheduled difference threshold, when difference is optionally greater than The second predetermined threshold is reduced when scheduled difference threshold.Alternatively, such as the lower half of 1304 block diagram of direct current arc fault detection device Shown in point: in RMS computing unit 1306, determining difference of the PSD of current signal in first time period between detection cycle. Then, in threshold adjustment unit 1307, increase by the second predetermined threshold when difference is lower than scheduled difference threshold, when difference height The second predetermined threshold is reduced when being equal to scheduled difference threshold.
In conclusion embodiment of the present invention determines whether to detect electric arc based on the judgement result of two threshold values to integrate Failure, solve should refuse when tripped tripping or should not when tripped unnecessary tripping the technical issues of.Moreover, with existing Frequency domain method is compared, and embodiment of the present invention only needs to be implemented software calculating, without additional hardware, also reduces hardware Cost.
It should be noted that step and module not all in above-mentioned each process and each structure chart be all it is necessary, can To ignore certain steps or module according to the actual needs.Each step execution sequence be not it is fixed, can according to need into Row adjustment.The division of each module is intended merely to facilitate the division functionally that description uses, and in actual implementation, a module can It is realized with point by multiple modules, the function of multiple modules can also be realized by the same module, these modules can be located at same In a equipment, it can also be located in different equipment.
Hardware module in each embodiment mechanically or can be realized electronically.For example, a hardware module It may include that the permanent circuit specially designed or logical device (such as application specific processor, such as FPGA or ASIC) are specific for completing Operation.Hardware module also may include programmable logic device or circuit by software provisional configuration (as included general procedure Device or other programmable processors) for executing specific operation.Mechanical system is used as specific, or using dedicated permanent Property circuit, or Lai Shixian hardware module (such as is configured) by software using the circuit of provisional configuration, can according to cost with Temporal consideration is to determine.
The present invention also provides a kind of machine readable storage medium, storage is as described in the present application for executing a machine The instruction of method.Specifically, system or device equipped with storage medium can be provided, store realization on the storage medium The software program code of the function of any embodiment in above-described embodiment, and make computer (or the CPU of the system or device Or MPU) read and execute the program code being stored in a storage medium.Further, it is also possible to pass through the instruction based on program code Operating system for calculating hands- operation etc. is set to complete partly or completely practical operation.It can also will be read from storage medium Program code write in memory set in the expansion board in insertion computer or write and be connected to a computer In the memory being arranged in expanding element, then the instruction based on program code makes to be mounted on expansion board or expanding element CPU etc. comes execution part and whole practical operations, to realize the function of any embodiment in above embodiment.
Storage medium embodiment for providing program code include floppy disk, hard disk, magneto-optic disk, CD (such as CD-ROM, CD-R, CD-RW, DVD-ROM, DVD-RAM, DVD-RW, DVD+RW), tape, non-volatile memory card and ROM.Selectively, Can by communication network from server computer download program code.
The foregoing is only a preferred embodiment of the present invention, is not intended to limit the scope of the present invention.It is all Within the spirit and principles in the present invention, any modification, equivalent replacement, improvement and so on should be included in protection of the invention Within the scope of.

Claims (18)

1. direct current arc fault detection method characterized by comprising
The electric current high fdrequency component (301) of DC current signal is detected in first time period;
When the number of the electric current high fdrequency component detected in the first time period is greater than the first predetermined threshold, described the The electric current high fdrequency component (302) of the detection DC current signal in second time period after one period;
When the number of the electric current high fdrequency component detected in the second time period is greater than the second predetermined threshold, direct current is determined Arc fault (303).
2. direct current arc fault detection method according to claim 1, which is characterized in that this method further include:
When the number of the electric current high fdrequency component detected in the first time period is less than or equal to first predetermined threshold, Determine no direct current arc fault;Or
When the number of the electric current high fdrequency component detected in the second time period is less than or equal to second predetermined threshold, Determine no direct current arc fault.
3. direct current arc fault detection method according to claim 1, which is characterized in that this method further include:
DC current signal in the first time period is analyzed, the analysis knot based on DC current signal in the first time period Fruit adjusts second predetermined threshold (304).
4. direct current arc fault detection method according to claim 3, which is characterized in that in the analysis first time period DC current signal, the analysis result based on DC current signal in the first time period adjust second predetermined threshold (304) include:
Determine difference of the power spectral density of current signal in the first time period between detection cycle;
When the difference is lower than scheduled difference threshold, increase by second predetermined threshold.
5. direct current arc fault detection method according to claim 3, which is characterized in that in the analysis first time period DC current signal, the analysis result based on DC current signal in the first time period adjust second predetermined threshold (304) include:
Determine difference of the power spectral density of DC current signal in the first time period between detection cycle;
When the difference is optionally greater than scheduled difference threshold, second predetermined threshold is reduced.
6. direct current arc fault detection method according to claim 4 or 5, which is characterized in that
Difference of the power spectral density of DC current signal between detection cycle includes: in the determination first time period Determine difference of the virtual value of current signal in the first time period between detection cycle.
7. direct current arc fault detection method according to claim 3, which is characterized in that in the analysis first time period DC current signal, the analysis result based on DC current signal in the first time period adjust second predetermined threshold (304) include:
Determine difference of the frequency domain character of DC current signal in the first time period between detection cycle;
When the difference is lower than scheduled difference threshold, increase by second predetermined threshold.
8. direct current arc fault detection method according to claim 3, which is characterized in that in the analysis first time period DC current signal, the analysis result based on DC current signal in the first time period adjust second predetermined threshold (304) include:
Determine difference of the frequency domain character of DC current signal in the first time period between detection cycle;
When the difference is optionally greater than scheduled difference threshold, second predetermined threshold is reduced.
9. direct current arc fault detection device (1200) characterized by comprising
First detection module (1201) detects the electric current high fdrequency component of DC current signal in first time period;
Second detection module (1202), when the electricity that the first detection module (1201) detect in the first time period When flowing the number of high fdrequency component greater than the first predetermined threshold, detection is described straight in second time period after the first time period Flow the electric current high fdrequency component of current signal;
Breakdown judge module (1203), when the electricity that second detection module (1202) detects in the second time period When flowing the number of high fdrequency component greater than the second predetermined threshold, direct current arc fault is determined.
10. direct current arc fault detection device (1200) according to claim 9, which is characterized in that
The breakdown judge module (1203), when the first detection module (1201) detect in the first time period Electric current high fdrequency component number be less than or equal to the first predetermined threshold when, determine no direct current arc fault;Or
It is small when the number for the electric current high fdrequency component that second detection module (1202) detects in the second time period When being equal to the second predetermined threshold, no direct current arc fault is determined.
11. direct current arc fault detection device (1200) according to claim 9, which is characterized in that further include:
Threshold adjustment module (1204) analyzes DC current signal in the first time period, is based on the first time period The analysis result of interior DC current signal adjusts second predetermined threshold.
12. direct current arc fault detection device (1200) according to claim 11, which is characterized in that
The threshold adjustment module (1204) determines that the power spectral density of DC current signal in the first time period is being examined The difference between the period is surveyed, when the difference is lower than scheduled difference threshold, increases by second predetermined threshold.
13. direct current arc fault detection device (1200) according to claim 11, which is characterized in that
The threshold adjustment module (1204) determines that the power spectral density of DC current signal in the first time period is being examined The difference between the period is surveyed, when the difference is optionally greater than scheduled difference threshold, reduces by second predetermined threshold.
14. direct current arc fault detection device (1200) according to claim 11, which is characterized in that
The threshold adjustment module (1204) determines that the frequency domain character of DC current signal in the first time period is detecting Difference between period increases by second predetermined threshold when the difference is lower than scheduled difference threshold.
15. direct current arc fault detection device (1200) according to claim 11, which is characterized in that
The threshold adjustment module (1204) determines that the frequency domain character of DC current signal in the first time period is detecting Difference between period reduces by second predetermined threshold when the difference is optionally greater than scheduled difference threshold.
16. direct current arc fault detection system (1300) characterized by comprising
Current sensor (1301) detects DC current signal;
Analog front end processing device (1302) extracts electric current high fdrequency component from the DC current signal;
The electric current high fdrequency component is converted to number format by analog-digital commutator (1303);
Direct current arc fault detection device (1304) detects the high frequency division of electric current of the number format in first time period Amount, when the number of the electric current high fdrequency component detected in the first time period is greater than the first predetermined threshold, described the The electric current high fdrequency component of the detection DC current signal in second time period after one period, when in the second time period When the number of the electric current high fdrequency component inside detected is greater than the second predetermined threshold, direct current arc fault is determined.
17. direct current arc fault detection system (1300) according to claim 16, which is characterized in that
The direct current arc fault detection device (1304), is also used to analyze DC current signal in the first time period, base Second predetermined threshold is adjusted in the analysis result of DC current signal in the first time period;
Wherein DC current signal in the analysis first time period, point based on DC current signal in the first time period Analysis result adjusts second predetermined threshold and comprises determining that the power spectral density of current signal in the first time period is detecting Difference between period increases by second predetermined threshold when the difference is lower than scheduled difference threshold, when the difference Second predetermined threshold is reduced when optionally greater than scheduled difference threshold;Or, determining DC current in the first time period Difference of the frequency domain character of signal between detection cycle increases described second when the difference is lower than scheduled difference threshold Predetermined threshold reduces by second predetermined threshold when the difference is optionally greater than scheduled difference threshold.
18. computer readable storage medium is stored thereon with computer program, which is characterized in that the computer program is located It manages when device executes and realizes such as the step of direct current arc fault detection method described in any item of the claim 1 to 8.
CN201711464045.4A 2017-12-28 2017-12-28 Direct current arc fault detection method, device and system Pending CN109975663A (en)

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