CN104601105B - Arc detection method for fault of photovoltaic system under abnormal light condition - Google Patents
Arc detection method for fault of photovoltaic system under abnormal light condition Download PDFInfo
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- CN104601105B CN104601105B CN201510012155.1A CN201510012155A CN104601105B CN 104601105 B CN104601105 B CN 104601105B CN 201510012155 A CN201510012155 A CN 201510012155A CN 104601105 B CN104601105 B CN 104601105B
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- 238000001514 detection method Methods 0.000 title claims abstract description 93
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Classifications
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02S—GENERATION OF ELECTRIC POWER BY CONVERSION OF INFRARED RADIATION, VISIBLE LIGHT OR ULTRAVIOLET LIGHT, e.g. USING PHOTOVOLTAIC [PV] MODULES
- H02S50/00—Monitoring or testing of PV systems, e.g. load balancing or fault identification
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/50—Photovoltaic [PV] energy
Abstract
The invention discloses an arc detection method for the fault of a photovoltaic system under an abnormal light condition. When an MPPT algorithm dynamic regulating system operating point is not caused by a fault arc accident, by allowing the fault arc characteristic quantity threshold value to tightly track the system operation point variation curve regulated by the MPPT algorithm, the circumstances that the fault arc detection electric quantity varies dynamically or lowers continuously caused by light change can be dealt, and the detection device can effectively detect fault arc in the photovoltaic system at any time can be ensured. According to the detection method, the fault arc detection precaution capacity of the photovoltaic system under abnormal light condition caused by changes of weather and environment is greatly improved, the misoperation problem caused by that the original set threshold value of the photovoltaic fault arc protection device is invalid is effectively solved, and the loophole that the traditional detection device is difficult to detect potential arc threats under the special situations is filled.
Description
Technical field
The invention belongs to the electric fault detection technique field of photovoltaic, and in particular to a kind of to be based on improper illumination condition subinverse
Become the photovoltaic system operating point that device MPPT algorithm is adjusted, these operating points of DC Line Fault electric arc detecting device dynamic tracking are adjusting
The judging characteristic amount threshold value of setting, the method for realizing photovoltaic system internal fault arc-detection under improper illumination condition.
Background technology
Growing tension along with global energy and environment sustainable development require, photovoltaic generation this novel environment friendly can
The renewable sources of energy obtain more and more extensive popularization and application in residential electricity consumption and industry and commerce field.In photovoltaic generating system, failure electricity
Arc is typically aging, damaged by line insulation or electric loop has the not operation reasons such as the connection loosening such as bus cases and causes
's.Fault electric arc can absorb most of energy of photovoltaic system generation and switch to high-temperature ionized gas when occurring, complete due to lacking
The DC Line Fault detection means supervision in orientation, this lasting high-temperature gas obviously can be by cable, electric equipment and header box
Burn；The substantial amounts of heat that fault electric arc electric discharge is persistently released is also possible to light the inflammable explosive article around photovoltaic system, finally draws
Play region area to have a power failure and explosive fire accident accident, easily cause the property loss of photovoltaic system component and related facility or even jeopardize
Life security.Therefore, it is anti-especially under improper illumination condition accurately to detect and disconnect fault electric arc under any circumstance
The fundamental way of model hazardous accidents.
1999, the U.S.'s GB for cooperating to draft with national electrical manufacturers association by Underwriters Laboratories
UL1699, mainly specifies to ac fault detection equipment quality testing standard, and Qiang Zhiyaoqius that AC system and civil buildings are sleeping
Fault electric arc detection protection device must be installed and be protected by room.Last century the nineties are the prosperous ages of photovoltaic system, but
Easily occur module, binding post and connection bus cases in system the problems such as loosen, cause fault electric arc to take place frequently, these fault electric arcs
Although electric current very little, the enough initiation fires of the energy for being generated threaten the security of the lives and property in surrounding.AC fault
The failure of detection means GB and the extensive application of photovoltaic system make the detection isolating problem of photovoltaic DC fault electric arc increasingly tight
It is high, GB UL1699B that the U.S. was formulated in 2011 DC Line Fault electric arc detecting device quality inspection problem formally with regard to photovoltaic system
Proposition standard.China also in propose in recent years with regard to AFDD be typically designed requirement and as electric fire monitoring system
Draft proplsal, it is seen that the preventing and treating of fault electric arc is extremely urgent in photovoltaic system.
At present, for photovoltaic system fault electric arc detect, the detection characteristic quantity threshold value researched and proposed both at home and abroad be based on be
System does not change this premise in normal table illumination external environment, operating point and system charge, is not directed to external environment
Change or accidental factor make the situation that illumination variation initiating system operating point and system charge change.And in improper illumination condition
Under (rainy weather, black clouds are unbroken, leaveves Long term Animal is covered etc. stablizes improper illumination weather environment and cirrocumulus is sailed, flown
Machine is skimmed over, leaveves are sailed, small bird flies over, sunrise sunset etc. is in short-term under illumination variation environment), the MPPT algorithm in inverter is just moved
State adjusts photovoltaic system operating point, low when the electricity of photovoltaic system is more normal, corresponding output characteristic curve and system charge
Also low when more normal, now once break down electric arc, and DC Line Fault electric arc detecting device gathers calculated feature
Amount is often unable to reach given threshold, makes the fault electric arc judging characteristic amount initial threshold set under normal illumination fail, causes
Device tripping.This just causes photovoltaic system to there is larger potential arc fault threat, and this low current fault electric arc persistently fires
Burn, also possess enough energy and damage photovoltaic system, initiation fire, bring life and property loss.
The content of the invention
It is an object of the invention to solving DC Line Fault arc protection device enters improper illumination condition in photovoltaic system
A kind of problem of the tripping that lower former given threshold fails and causes, there is provided the photovoltaic system failure electricity under improper illumination condition
Arc detection method.
To reach above-mentioned purpose, technical scheme below is present invention employs：
The fault arc detection method is comprised the following steps：
In the case where photovoltaic system does not break down arc event, known based on the MPPT algorithm action signal in inverter
Other photovoltaic system operating point changes, and being changed to be adjusted in synchronism in DC Line Fault electric arc detecting device based on photovoltaic system operating point is used for
The characteristic quantity threshold value that fault electric arc event judges so that the characteristic quantity threshold value is with the system charge in photovoltaic system operating point
Change and same variation tendency is presented.
The fault arc detection method specifically includes following steps：
1) DC Line Fault electric arc detecting device carries out fault electric arc detection according to the characteristic quantity threshold value, and judges currently to adopt
Whether the sample moment breaks down arc event, if breaking down arc event, counting variable N is counted, and then goes to step 3)；
If not breaking down arc event, counting variable N is reset, step 2 is gone to)；
2) judge the whether action of MPPT algorithm in inverter, if action, judge that current sample time photovoltaic system enters
Enter improper illumination condition, DC Line Fault electric arc detecting device reads in the photovoltaic system operating point after the variation of inverter output,
The spy is calculated with reference to the corresponding photovoltaic system operating point of initial set value and initial set value of the characteristic quantity threshold value
The amount of levying threshold value corresponding setting value when upper once fault electric arc is detected, is then back to step 1) carry out fault electric arc inspection next time
Survey；If not operating, keep the current set value of the characteristic quantity threshold value constant, be then back to step 1) carry out failure next time
Arc-detection；
3) whether failure judgement arc event recurs, if fault electric arc event recurs N0Secondary, N has reached and sets
Definite value N0, then judge the electric arc that breaks down in photovoltaic system, take corresponding protective measure；If fault electric arc event is not recurred
N0Secondary, N does not have reached setting value N0, then 1) return to step is continuing with the current set value of the characteristic quantity threshold value is carried out down
Primary fault arc-detection.
The frequency of the sampling is 10kHz～100kHz, N0Span be 3～5.
Calculate in the setting value of the characteristic quantity threshold value, reflect photovoltaic system corresponding to the initial set value of characteristic quantity threshold value
The system charge of the photovoltaic system operating point behind operating point and variation should be consistent, and the change of the numerical value of the system charge is only by light
Cause according to condition change.
For the photovoltaic system constituted according to remaining photovoltaic module after fault electric arc testing result excision failure photovoltaic block
System, should initialize to the setting value of the characteristic quantity threshold value according to the corresponding photovoltaic system operating point of the photovoltaic module,
Then according to step 1) to step 3) proceed fault electric arc detection.
The MPPT algorithm action signal and photovoltaic system operating point change by DC Line Fault electric arc detecting device with it is inverse
Obtain after becoming device communication.
The present invention has following beneficial technique effect：
1) the method hardware is realized simple, it is only necessary to DC Line Fault electric arc detecting device and inversion are added in former photovoltaic system
Order wire between device, it is to MPPT algorithm action signal and the operating point transmission of photovoltaic system dynamic adjustment, with low cost；
2) when fault electric arc causes photovoltaic system operating point to change, characteristic quantity threshold value keeps constant to the method, effectively shuts out
Absolutely fault electric arc disturbs this interference factor to system operating point, enhances fault electric arc detection under improper illumination condition
Reliability；
3) the method for betide under improper illumination condition the fault electric arc of photovoltaic system also can accurate and effective detection,
The scope of DC Line Fault electric arc detecting device identification of defective electric arc is widened so that DC Line Fault arc protection device is in any ring
Under border can accurately and reliably action, the timely fault electric arc in cut-out photovoltaic system, it is to avoid it is potential in the case of these therefore
Barrier electric arc threatens the life and property loss for causing；
4) the method cuts off failure photovoltaic block after fault electric arc is found in time, and according to new operating point now, to event
The DC Line Fault electric arc detecting device characteristic quantity threshold value of barrier photovoltaic block place photovoltaic string and inverter end is re-established so that remaining
Photovoltaic module still energy normal table work, substantially prolongs working time of the photovoltaic system under frequent non-illumination condition, increases
Economic benefit is added.
Description of the drawings
Fig. 1 a are one of photovoltaic system fault arc detection method flow chart under the improper illumination condition of the present invention；
Fig. 1 b are two of the photovoltaic system fault arc detection method flow chart under the improper illumination condition of the present invention；
Fig. 2 is that the detection method of the present invention is applied to the spy comprising the DC Line Fault electric arc detecting device for being integrated in inverter
Determine photovoltaic system theory diagram；
Fig. 3 is that the detection method of the present invention is applied to the spy comprising the DC Line Fault electric arc detecting device for being integrated in photovoltaic string
Determine photovoltaic system theory diagram；
Fig. 4 is that the detection method of the present invention is applied to the spy comprising the DC Line Fault electric arc detecting device for being integrated in photovoltaic block
Determine photovoltaic system theory diagram；
Fig. 5 a are that the stable normal illumination of fine day switchs to overcast and rainy this and stablizes under improper illumination weather environment in inverter
Adjustment curve of the MPPT algorithm to photovoltaic system operating point；
Fig. 5 b switch to overcast and rainy this for the stable normal illumination of fine day and stablize DC Line Fault electricity under improper illumination weather environment
The corresponding judging characteristic amount threshold curve that arc detection means real-time tracking photovoltaic system operating point generates；
Fig. 5 c are that the stable normal illumination of fine day switchs to photovoltaic system after overcast and rainy this stablizes improper illumination weather environment and dashes forward
Send out fault electric arc curve；
Fig. 6 a are this tune of MPPT algorithm to photovoltaic system operating point in inverter under illumination variation environment in short-term of sunset
Pitch curve；
Fig. 6 b are this DC Line Fault electric arc detecting device real-time tracking photovoltaic system under illumination variation environment in short-term of sunset
The corresponding judging characteristic amount threshold curve that operating point generates；
Fig. 7 a sail this for cirrocumulus, and in inverter, MPPT algorithm works to photovoltaic system under illumination variation environment in short-term
The adjustment curve of point；
Fig. 7 b sail this DC Line Fault electric arc detecting device real-time tracking light under illumination variation environment in short-term for cirrocumulus
The corresponding judging characteristic amount threshold curve that volt system operating point generates；
Fig. 7 c sail for cirrocumulus after catastrophic failure electric arc curve.
In figure：1st, photovoltaic system；2nd, DC Line Fault electric arc detecting device；3rd, inverter；30th, inverter port；31st, inversion
Device port；4th, order wire；5th, trip gear；6th, chopper；7th, AC network；8th, detect electricity device；9th, short switch；10、
Photovoltaic module.
Specific embodiment
The present invention is described in detail with reference to the accompanying drawings and examples.
A kind of photovoltaic system fault arc detection method referring to Fig. 1 a, under improper illumination condition：Confirming photovoltaic system
After the arc event that do not break down in system, then MPPT algorithm motion detection is carried out, after action, just make DC Line Fault arc-detection fill
The change of the given threshold dynamic tracking operating point in putting.Calculated by making failure judgement arc characteristic amount threshold value tight tracking MPPT
The system operating point that method is adjusted becomes moving curve, just can tackle illumination variation initiating failure arc-detection electricity dynamic change or continue
The situation such as low, ensure detection means can fault electric arc of the effective detection in photovoltaic system at any time, complete improper illumination bar
Fault electric arc detection under part, effectively eliminates interference of the fault electric arc to system operating point.The present invention greatly improves light
Fault electric arc detection prevention ability of the volt system in the case where the improper illumination condition for causing such as being changed by weather environment, compensate for passing
System detection means to improper illumination condition under potential electric arc threaten the leak for being difficult to detect, efficiently solve photovoltaic failure electricity
Tripping problem of the arc protection device under above-mentioned improper illumination condition.
With reference to Fig. 1 b, the step of to photovoltaic system fault arc detection method under improper illumination condition of the present invention
It is specifically described.
The initialization procedure of step one, fault arc detection method：Including the clearing of inverter port reset, event of failure
Number N reset clearings, typing photovoltaic system initial characteristicses amount threshold value F and its operating point (the corresponding photovoltaic system of initial characteristicses amount threshold value
Normal illumination environment E residing for system be able to make whole system work in rated condition (P, U), wherein, P=PN, U=UN, PNFor specified
Power, UNFor rated voltage) and order wire communication mode arrange etc..
Step 2, DC Line Fault electric arc detecting device are every certain sampling time T1Just the electric quantity signal of detecting system,
Bring into characteristic quantity calculates formula and compare with setting characteristic quantity threshold value now, judge whether the arc event that breaks down.If sending out
Raw fault electric arc event, then be designated as primary fault arc event, and corresponding counts variable N is counted Jia one, turns to step 6；If not sending out
Raw fault electric arc event, then judge that current photovoltaic system does not break down electric arc, even if N has the event that value is also that accidental factor causes
Barrier electric arc erroneous judgement, resets variable N, turns to step 3.
Wherein, sampling time T1It is less, sample frequency f1Higher, the detection to fault electric arc event generation time is more accurate,
Sensitivity of the photovoltaic fault electric arc detecting system to fault electric arc is also higher, and combined with hardware design considers, f110kHz is taken as typically
～100kHz.
Step 3, confirmation system do not break down after arc event, detect that inquiry is connected to inverter with direct current event immediately
Order wire between barrier electric arc detecting device whether there is MPPT action signals.
, once entering under improper illumination condition, the illumination that photovoltaic module is subject to will be compared with normal illumination dynamic for photovoltaic system
Change or another illumination stable state is entered in short-term after dynamic change persistently.Now photovoltaic system U-I output characteristic curves will be sent out therewith
Changing, it is inevitable low compared with U-I output characteristic curves during normal illumination, U-I output characteristic curves after change with do not change
System load characteristic curve intersection, it is determined that new system operating point, touch MPPT algorithm adjustment operating point in inverter until
System output power is maximum.Now, in inverter, MPPT algorithm action makes the transition of inverter port send high level signal so that
Order wire transmits high level and keeps, and the change curve of photovoltaic system operating point is subsequently exported from another port；If inverter
Middle MPPT algorithm is failure to actuate, then inverter port is output as low level and keeps.
Step 4, DC Line Fault electric arc detecting device learn now MPPT algorithm by inquiring about detection order wire transmission signal
Whether action.If order wire input is high level signal, MPPT algorithm action in judgement system is the light by suffered by photovoltaic block
Change causes, and system operating point changes, and now photovoltaic system turns to step 5 under improper illumination condition；If
Order wire input is low level signal, then judge that the MPPT algorithm in inverter does not occur action, and photovoltaic system operating point is not sent out
Changing, photovoltaic module are normally run under continual and steady illumination condition, keep former setting characteristic quantity threshold value constant, return
Return step 2 and proceed the detection of next round fault electric arc.
Here improper illumination condition would generally the change of initiating system operating point, cause that system detectio electricity is low to be caused
Initial threshold fails and the failure of direct-current arc detection means, mainly has situations below：1) photovoltaic system enters rainy weather, black clouds
Improper illumination weather environment is stablized in unbroken, leaveves Long term Animal covering etc., and the illumination that photovoltaic module is subject to will be experienced extremely short
New illumination stable state is entered after the dynamic change of time, photovoltaic system output characteristic curve changes to new state therewith；2) photovoltaic
System runs into that cirrocumulus is sailed, aircraft is skimmed over, leaveves are sailed, small bird flies over etc. in short-term under illumination variation environment, and photovoltaic module is received
To illumination will experience the dynamic change of long period after recover to former normal illumination stable state, photovoltaic system output characteristic curve
New state is changed to therewith, is recovered to original state after short stay；3) photovoltaic system enters the light in short-term such as sunrise sunset
According under changing environment, the illumination that photovoltaic module is subject to will experience the lasting dynamic change of long period, and photovoltaic system output is special
Linearity curve continues dynamic change to new state.
Step 5, confirmation system do not break down after arc event, and inverter inscribes MPPT algorithm dynamic when gathering this
The operating point of adjustment is simultaneously exported by port, the new system work of the order wire transmission to be obtained such as DC Line Fault electric arc detecting device
Point.After DC Line Fault electric arc detecting device reads in new system operating point now, according to initial setting characteristic quantity threshold value and
Its corresponding specified photovoltaic system operating point, is calculated the new settings characteristic quantity threshold value read in the time period next time.Utilize
Replace former threshold value as the setting value of characteristic quantity criterion according to the new threshold value after the adjustment of system operating point, return to step two continue into
Row next round fault electric arc detects that the characteristic quantity threshold value being achieved under improper illumination condition is real to the dynamic of system operating point
When track.
The inventive method proposes to carry out MPPT algorithm whether action is inquired about before fault electric arc detection next time, so obtain
The order of accuarcy at the real action moment of MPPT algorithm and photovoltaic system operating point change moment each depends on the detection of fault electric arc
Frequency, that is, system charge sample frequency f1。
Step 6, the misoperation for causing DC Line Fault electric arc detecting device in order to avoid accidentalia, by setting failure
Arc event counting variable threshold value N0, it is believed that only fault electric arc event is recurred and reaches N0After secondary, just think occur in system
Fault electric arc, thus improves DC Line Fault electric arc detecting device detection reliability.If N=N0, then produce in judging photovoltaic system
Fault electric arc, the trip gear cut-off breaker in DC Line Fault electric arc detecting device control respective lines, extinguishes failure electricity
Arc, and alarm is sent to supervisor in time, if remaining photovoltaic module is still after further requirement excision failure photovoltaic block
Normal to run work, now the electricity of failure photovoltaic block place photovoltaic string and inverter end changes, should be according to current
The new operating point of system is re-established to the characteristic quantity threshold value in these DC Line Fault electric arc detecting devices；If N is ＜ N0, then need into
One step carries out fault electric arc detection and avoids accidental malfunction from disturbing the judgement of fault electric arc, now as system may break down electricity
Arc, system operating point and electric quantity change are probably to be caused by fault electric arc, former given threshold should be kept constant, return to step
Two proceed the detection of next round fault electric arc.
Wherein, fault electric arc event count variable threshold N0Bigger, detected system charge change is by failure electricity
The probability that arc causes is higher, and fault electric arc detection reliability is also higher, considers with reference to the requirement of fast shut-off fault electric arc, N0One
As be taken as 3～5.
With reference to Fig. 2, illustrate the detection method of the application present invention in comprising the DC Line Fault arc-detection for being integrated in inverter
The specific photovoltaic system of device.
The output of photovoltaic system 1 dc power in Fig. 2, Jing choppers 6, detection electricity device 8 are input into into inverter 3, inverse
Unidirectional current is changed into alternating current and is delivered to AC network 7 by change device 3.
Under normal table illumination condition, do not break down electric arc when, corresponding inverter port 30 remains low level
Signal, will not trigger the change curve of the output photovoltaic system of inverter 3 operating point, can't Transmission system work on order wire 4
Point.Now the characteristic quantity threshold value in DC Line Fault electric arc detecting device 2 keeps constant, by detecting that electricity device 8 is calculated
Differentiate characteristic quantity, and compare with original start characteristic quantity threshold value all the time, the fault electric arc carried out under normal lighting conditions was detected
Journey.Once Judging fault arc event occurs, corresponding counts variable N adds 1, keeps the constant fault electric arc that continues of characteristic quantity threshold value to examine
Survey, be prevented effectively from new settings threshold value and disturbed by fault electric arc.Only when the counting variable reaches N0, just judge photovoltaic system
In generate fault electric arc, control 5 cut-off breaker 6 of trip gear of DC Line Fault electric arc detecting device 2 extinguishes fault electric arc,
And alarm is sent to supervisor in time；Otherwise, reset counting variable N and exclude the accidentalia for causing erroneous judgement, and proceed
Detection judges.
And cirrocumulus is sailed, aircraft is skimmed over, leaveves are sailed in photovoltaic system experience, the illumination variation ring in short-term such as sunrise sunset
Border experiences suddenly that prolonged rainy weather, black clouds be unbroken, leaveves Long term Animal is covered etc. by normal illumination environment and stablizes non-
During normal illumination weather environment, before photovoltaic system illumination relatively, state changes, and the output characteristic curve of photovoltaic system occurs
Change, triggers the MPPT algorithm action in inverter 3 and starts to adjust photovoltaic system operating point to maximum power point.Now, inversion
Device port 30 keeps output high level signal, the triggering DC Line Fault of Jing order wires 4 electric arc detecting device 2 to read in another inverter end
The photovoltaic system operating point change curves exported by mouth 31.DC Line Fault electric arc detecting device 2 obtains photovoltaic system work now
After making point (P', U'), according to the corresponding photovoltaic system normal illumination operating point (P, U) of former setting characteristic quantity threshold value F, it is calculated
New settings characteristic quantity threshold value in next sampling time sectionThus make given threshold real-time tracking photovoltaic system
Operating point changes, constantly by the use of the threshold value after new adjustment as characteristic quantity criterion, afterwards just with carrying out the same under normal circumstances
Fault electric arc event judges and starts the links such as protection.In system completely into overcast and rainy or after sunset is finished, photovoltaic system connects
The illumination received does not change, and now system operating point also just no longer changes, and keeps Low threshold constant, thus tackles anon-normal ordinary light
Detection electricity according under the conditions of reduces situation.
Additional description is needed, if DC Line Fault electric arc detecting device 2 detects after fault electric arc only disengagement failure light
Volt block rather than whole photovoltaic system, then to ensure remaining photovoltaic module still normal work, be integrated in the DC Line Fault of inverter
Threshold value in electric arc detecting device 2 needs to reinitialize according to now photovoltaic system output services point.
With reference to Fig. 3, illustrate the detection method of the application present invention in comprising the fault arc detection device for being integrated in photovoltaic string
Specific photovoltaic system.
Assume that the photovoltaic system in Fig. 3 includes M photovoltaic string.Contrast Fig. 2, detection electricity device 8, the direct current event in Fig. 3
The trip gear 5 of barrier electric arc detecting device 2 and its corresponding control, chopper 6 are distributed in each photovoltaic string rather than inverter end.Cause
This, order wire 4 of the system on hardware also should be consistent with the number of DC Line Fault electric arc detecting device 2, be M.Its
Normal illumination environment, in short-term illumination variation environment and stablize under improper illumination weather environment, the detection to fault electric arc is protected
It is consistent with photovoltaic system shown in Fig. 2.
To note here is that the spy under former normal illumination working condition, in each DC Line Fault electric arc detecting device 2
The amount of levying threshold value is the photovoltaic string electricity setting for being located, and operating point under former normal illumination [(P, U), wherein, P=PN,
U=UN] and the new operating point of photovoltaic system (P', U') that collects all or for whole photovoltaic system, so newly
Given threshold computing formula is stillThe electric arc in addition, once photovoltaic system breaks down, if only cutting off failure photovoltaic
The photovoltaic string that block rather than whole failure photovoltaic block are located, then to ensure cause barrier photovoltaic string still normal work, be integrated in failure
Threshold value in the DC Line Fault electric arc detecting device 2 of string needs to reinitialize according to now photovoltaic system output services point.
With reference to Fig. 4, illustrate the detection method of the application present invention in comprising the DC Line Fault arc-detection for being integrated in photovoltaic block
The specific photovoltaic system of device.
Assume that the photovoltaic system in Fig. 4 includes M photovoltaic string, each photovoltaic string includes N number of photovoltaic module.Contrast Fig. 2, figure
The trip gear 5 of detection electricity device 8, DC Line Fault electric arc detecting device 2 and its corresponding control in 4, chopper 6, short circuit
Switch 9 is distributed in each photovoltaic block rather than inverter end, and chopper 6 guarantees only to cut off failure photovoltaic block together with short switch 9
And do not affect other normal photovoltaic block operations.Therefore, order wire 4 of the system on hardware also should be with DC Line Fault arc-detection
The number of device 2 is consistent, and is M × N.In the same manner, under former normal illumination working condition, each DC Line Fault arc-detection is filled
It is that the new settings threshold value in next sampling time section is still for the photovoltaic block electricity setting being located to put the characteristic quantity threshold value in 2
ForUsing Fig. 4 photovoltaic system structure and choose the input electricity of DC Line Fault arcing device 2 as input point
Receive illumination variation to photovoltaic system most sensitive, but hardware input is also relatively large.
With reference to Fig. 5, illustrate that fine day is dashed forward and turn stablizing under improper illumination weather environment with rainy weather as representative, direct current event
Barrier electric arc detecting device tracking photovoltaic system operating point dynamic regulation generates and differentiates the process of characteristic quantity threshold value and tackle these rings
The fault electric arc detection process happened suddenly under border.
Fig. 5 a are dashed forward by fine day and turn, by taking rainy weather as an example, to illustrate that photovoltaic system is entered from normal table illumination weather environment
Rainy weather, black clouds are unbroken, leaveves are blocked for a long time, Long term Animal is stopped etc. stablizes the photovoltaic system of improper illumination weather environment
Operating point variation track.Fine day before is regarded as 1 state residing for photovoltaic system, and its intensity of illumination corresponds to E1(W/m2),
The output characteristic curve of photovoltaic system corresponds to L1, system stability operating point be A (P, U), the initial given threshold of judging characteristic amount
For F；Final rainy weather is regarded as 2 states residing for photovoltaic system, and its intensity of illumination corresponds to E2(W/m2), photovoltaic system
Output characteristic curve correspond to L2, system stability operating point is B (P', U').
Before system under fine day illumination, in t1Moment dashes forward when meeting overcast and rainy this quick Changes in weather, photovoltaic system
After the change of a very short time is experienced in illumination, in t2Moment immediately enters a relatively low stable illumination conditions (2 state).Light
It is rapider that volt system stablizes improper illumination weather environment into above-mentioned these, so system is in L1With L2Between it is discrete dynamic
State adjustment curve LiIt is less, corresponding new system operating point (P'i, U'i) also less.According to new threshold setting method F'=P' × C
(in the photovoltaic system of different structure, C values are different, but for same photovoltaic system different operating point C is fixed value) obtain figure
5b。
Fig. 5 c illustrate photovoltaic system into the t after overcast and rainy3Moment breaks down, and is detected electricity amplitude relatively normal steady
Have dropped in determining illumination weather environment, its decline degree depends on the reduction degree for stablizing improper illumination weather environment illumination.
Therefore, the sampling electric quantity signal after decay brings characteristic quantity calculates formula income value into very likely less than initial given threshold, causes
Device tripping causes detection failure.But the judgment threshold in application drawing 5b, equivalent to DC Line Fault electric arc detecting device to failure
The examination criteria of electric arc changes with the change of external environment illumination so that the accurate tracing detection dress of failure judgement electric arc standard
The input electric quantity change track put.According to the requirement of the inventive method, there is moment t in fault electric arc in threshold value3Keep later not
Become, rather than continue to follow the low system operating point caused by fault electric arc, t in such as Fig. 5 b3Shown in dotted line after moment, effectively
Avoid the setting of characteristic quantity threshold value to disturb system charge by fault electric arc, thus accurately detect the event under each system operating point
Barrier electric arc.
The illumination variation in short-term such as cirrocumulus is sailed, aircraft is skimmed over, leaveves are sailed, small bird flies over, photovoltaic system is from normal steady
Determine illumination weather environment enter have a veil stablize improper this process of illumination weather environment with consistent described in Fig. 5, it is different
To be that state 2 this steady-state process in Fig. 5 a continues very short, then experience of short duration Dynamic Regulating Process and return to once more
State 1 this stable process.Therefore, photovoltaic system break down in masking process electric arc detection method it is similar with Fig. 5.
With reference to Fig. 6, illustrate under the weather environment of illumination variation in short-term with sunset as representative, DC Line Fault electric arc detecting device
Tracking photovoltaic system operating point dynamic regulation generates the process of differentiation characteristic quantity threshold value and tackles the failure happened suddenly under these environment
Arc-detection process.
Fig. 6 a illustrate that photovoltaic system slowly enters night (sunset) from normal table illumination weather environment by taking sunset as an example
Or the photovoltaic system work of the illumination variation weather environment in short-term such as normal table illumination weather environment (sunrise) is slowly entered from night
Make point variation track.The fine day of beginning is regarded as 1 state residing for photovoltaic system, and its intensity of illumination corresponds to E1(W/m2), light
The output characteristic curve of volt system corresponds to L1, system stability operating point is A (P, U), and judging characteristic amount given threshold is F；Most
Whole Critical Light corresponds to E according to 2 states being regarded as residing for photovoltaic system, its intensity of illumination2(W/m2), the output of photovoltaic system
Characteristic curve corresponds to L2, system operating point is B (P', U'), then along L2To C (0, U'), [wherein, U' is for adjustment operating point
The threshold voltage of inverter work].Now whole photovoltaic system has a voltage output and no current output, and correspondence system is in Critical Light
Open-circuit working point according under.
System enters gradually Critical Light and shines or shines from Critical Light from fine day full exposure enter gradually full exposure, photovoltaic system
Illumination need to experience the gradual change of about a hour.Dynamic Regulating Process in the case of these is slow, so selected by centre from
Scattered dynamic adjusting system operating point is more, still obtains Fig. 6 b by new threshold setting method.
When especially sunset closes to an end if failure betides this process, it is detected electricity amplitude and declines to a great extent, it is inevitable
Cause DC Line Fault arc protection device tripping, small current electric arc sustained combustion destruction photovoltaic module even initiation fire.So
The judgment threshold of the multiple dynamic changes in application drawing 6b, corresponding to the multiple working conditions between state 1 and state 2, effectively
Prevent the incipient fault electric arc under these environment.After state 2, threshold value is 0, now the output of photovoltaic system no current, voltage also pole
It is little, thus the detection to fault electric arc can be stopped.If it should be noted that adopting voltage here for initial threshold correspondence work
Make the reflection characteristic quantity of point and current new operating point, then the reduction formula of new settings threshold value is changed intoThreshold value is being faced
Still follow after boundary's illumination operating point change and change until system quit work completely (output current, voltage are 0) be
Only.
Fig. 5 and Fig. 6 demonstrate the inventive method and can effectively prevent the photovoltaic system fault electric arc under improper illumination condition
Problem, ensures that photovoltaic system remains to normal work under the common illumination condition such as overcast and rainy, sunrise sunset, thus makes full use of
The improper illumination of these weather environments, also add the generating energy of system while extending whole photovoltaic system generating dutation
Power.
With reference to Fig. 7, elaboration is skimmed under the weather environment of illumination variation in short-term as representative with aircraft, DC Line Fault arc-detection
Device tracking photovoltaic system operating point dynamic regulation generates the process for differentiating characteristic quantity threshold value and terminates processus aboralis with these environment are tackled
The fault electric arc detection process sent out.
Fig. 7 a illustrate that photovoltaic system floats from normal table illumination weather environment into cirrocumulus so that cirrocumulus is sailed as an example
Cross, the photovoltaic system operating point variation track of the illumination variation environment in short-term such as aircraft is skimmed over, leaveves are sailed, small bird flies over.By front
Described, the photovoltaic system environment in the case of these, recovers to shape after staying for some time to state 2 again in 1 quick regulation of state
State 1.
Fig. 7 c illustrate the fault electric arc situation under a kind of improper illumination condition of very coincidence.Photovoltaic system is this
Illumination variation environment terminates to will then revert to (t during normal illumination in short-term3Moment) system burst failure condition, normal illumination order
MPPT algorithm height-adjusting system operating point, the sample detecting electricity amplitude in system raise, but series fault electricity now occurs just
Arc makes sample detecting electricity decline, and the energy that photovoltaic system is strengthened by illumination and increased all supplies fault electric arc just so as to
It is constantly under state 2, similar to cirrocumulus always in photovoltaic system upper end.And current fault electric arc detection algorithm design
Initial threshold can hide Changes in weather is mistakenly considered into series fault arc, i.e., not will be considered that t1To t2It is failure that electricity changes
What electric arc caused, then as system detectio electricity persistently keeps constant, therefore in t3The fault electric arc that moment occurs is relied on
Original start threshold value cannot be detected.
By detection method, by the change judgment threshold in Fig. 7 b, DC Line Fault electric arc detecting device threshold is made
Value is in t1Moment persistently drops, and in t3Threshold value after moment failure keeps this to turn down after occurring is constant, makes failure electricity now
Arc is detected.
The present invention when MPPT algorithm dynamic adjusting system operating point is caused by fault electric arc event, by making judgement
The system operating point that fault electric arc characteristic quantity threshold value tight tracking MPPT algorithm is adjusted becomes moving curve, just can tackle illumination variation and draw
Send out fault electric arc detection electricity dynamic change or continue the situation such as low, ensure detection means can at any time effective detection to photovoltaic system
Fault electric arc in system.The inventive method compensate for the leak that fault electric arc detects protection device, improve DC Line Fault electric arc
The ability of detection means reply weather environment change so that DC Line Fault arc-detection protection device in any environment can be accurate
Really reliable action, cuts off the fault electric arc in photovoltaic system so that photovoltaic system occurs fire in these cases in time
Probability is greatly reduced, it is ensured that photovoltaic system in any environment can safe operation, prevent from being difficult what is detected under these environment
Life and property loss caused by fault electric arc, has ensured the security of the lives and property conscientiously.The inventive method is for DC Line Fault electricity
As usual the photovoltaic system run after the photovoltaic system of any integrated form of arc detection means, photovoltaic block of fixing a breakdown carries out improper
Illumination detection is suitable for.
Claims (5)
1. the photovoltaic system fault arc detection method under a kind of improper illumination condition, it is characterised in that：The fault electric arc is examined
Survey method is comprised the following steps：
In the case where photovoltaic system does not break down arc event, based on the MPPT algorithm action signal identification light in inverter
Volt system operating point changes, and changing to be adjusted in synchronism in DC Line Fault electric arc detecting device based on photovoltaic system operating point is used for failure
The characteristic quantity threshold value that arc event judges so that the characteristic quantity threshold value is with the change of the system charge in photovoltaic system operating point
Change and same variation tendency is presented；
The fault arc detection method specifically includes following steps：
1) DC Line Fault electric arc detecting device carries out fault electric arc detection according to the characteristic quantity threshold value, and when judging present sample
Whether arc event, if breaking down arc event, counting variable N is counted, and then goes to step 3 if breaking down at quarter)；If not
Break down arc event, then reset counting variable N, go to step 2)；
2) judge the whether action of MPPT algorithm in inverter, if action, judge that current sample time photovoltaic system is entered non-
Normal lighting conditions, DC Line Fault electric arc detecting device read in the photovoltaic system operating point after the variation of inverter output, with reference to
The corresponding photovoltaic system operating point of initial set value and initial set value of the characteristic quantity threshold value is calculated the characteristic quantity
Threshold value corresponding setting value when upper once fault electric arc is detected, is then back to step 1) carry out fault electric arc detection next time；
If not operating, keep the current set value of the characteristic quantity threshold value constant, be then back to step 1) carry out failure electricity next time
Arc is detected；
3) whether failure judgement arc event recurs, if fault electric arc event recurs N0It is secondary, then judge in photovoltaic system
Break down electric arc, takes corresponding protective measure；If fault electric arc event does not recur N0Secondary, then 1) return to step continues to make
Fault electric arc detection next time is carried out with the current set value of the characteristic quantity threshold value.
2. photovoltaic system fault arc detection method according to claim 1 under a kind of improper illumination condition, its feature
It is：The frequency of the sampling is 10kHz～100kHz, N0Span be 3～5.
3. photovoltaic system fault arc detection method according to claim 1 under a kind of improper illumination condition, its feature
It is：Calculate in the setting value of the characteristic quantity threshold value, reflect photovoltaic system work corresponding to the initial set value of characteristic quantity threshold value
The system charge of the photovoltaic system operating point after making point and changing should be consistent, and the change of the numerical value of the system charge is only by illumination
Condition change causes.
4. photovoltaic system fault arc detection method according to claim 1 under a kind of improper illumination condition, its feature
It is：For the photovoltaic system constituted according to remaining photovoltaic module after fault electric arc testing result excision failure photovoltaic block,
The setting value of the characteristic quantity threshold value should be initialized according to the photovoltaic module corresponding photovoltaic system operating point, then
According to step 1) to step 3) proceed fault electric arc detection.
5. photovoltaic system fault arc detection method according to claim 1 under a kind of improper illumination condition, its feature
It is：The MPPT algorithm action signal and photovoltaic system operating point are changed by DC Line Fault electric arc detecting device and inverter
Obtain after communication.
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Effective date of registration: 20180108 Address after: 215500 Jiangsu city of Suzhou province Changshou City Yushan Industrial Park District Jianye Road No. 8 Patentee after: Changshu Switchgear Manufacturing Co., Ltd. (Former Changshu Switchgear Factory) Address before: 710049 Xianning Road, Shaanxi, China, No. 28, No. Patentee before: Xi'an Jiaotong University |