CN106655086B - A kind of header box protective device and method - Google Patents
A kind of header box protective device and method Download PDFInfo
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- CN106655086B CN106655086B CN201611085854.XA CN201611085854A CN106655086B CN 106655086 B CN106655086 B CN 106655086B CN 201611085854 A CN201611085854 A CN 201611085854A CN 106655086 B CN106655086 B CN 106655086B
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/26—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to difference between voltages or between currents; responsive to phase angle between voltages or between currents
- H02H3/32—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to difference between voltages or between currents; responsive to phase angle between voltages or between currents involving comparison of the voltage or current values at corresponding points in different conductors of a single system, e.g. of currents in go and return conductors
- H02H3/325—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to difference between voltages or between currents; responsive to phase angle between voltages or between currents involving comparison of the voltage or current values at corresponding points in different conductors of a single system, e.g. of currents in go and return conductors involving voltage comparison
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Abstract
The present invention relates to a kind of header box protective device and method, the header box includes photovoltaic cable, direct current cables and breaker, and the header box protective device includes collecting unit, logic unit and execution unit；The voltage signal of the collecting unit acquisition direct current cables and the voltage signal of photovoltaic cable branch road；The logic unit includes the comparison module of parallel connection, and comparison module is electrically connected with the collecting unit, and comparison module includes multiplication comparator component and diode, and multiplication comparator component accesses voltage signal and comparison voltage, output end series diode.The beneficial effects of the invention are as follows the monitoring for carrying out short trouble to photovoltaic cable and direct current cables simultaneously can effectively identify when short trouble occurs for any of which and send out trip command respectively, to realize failure removal, multiple protective is formd to cable.
Description
Technical field
The present invention relates to field of photovoltaic power generation, and in particular to a kind of header box protective device.
Background technology
Header box is a kind of electrical equipment applied in photovoltaic generating system, is responsible for the direct current for generating photovoltaic module
Electricity is transmitted to photovoltaic DC-to-AC converter after its primary confluence.In order to ensure reliability, the safety of power generation, header box is equipped with anti-
The protections such as thunder, overcurrent and overload.But it is monopole ground connection that the photovoltaic cable failure rate that is connect with header box is highest
Failure (plus earth or cathode ground connection), the voltage that such failure causes non-faulting pole increases, and the device inside header box is in height
It is breakdown in the case of pressure, to cause fire.Since the current detection accuracy of traditional header box is only 3%~5%, Wu Fajing
Really detect string formation branch, and the size of electric current is bigger by ambient lighting and ambient temperature effect.Therefore this is header box
A kind of defect in design.
The present inventor once applied for patent document on this question, application No. is " CN201521132948.9 ", Patent No. "
CN205509468U ", the utility model of entitled header box protective device.The utility model proposes collecting unit, logic unit
And the structure of execution unit, logic unit are electrically connected to receive the voltage signal transmitted from collecting unit, so with collecting unit
The electric signal is compared with comparison voltage afterwards, is set when the absolute value of the difference of the voltage signal and comparison voltage is greater than or equal to
Logic unit sends to execution unit and instructs when definite value；And execution unit is electrically connected with logic unit and according to from logic unit
The instruction control breaker open operation transmitted.The invention solves the problems, such as short-circuit detection protection.But the confluence that original patent refers to
Case is to realize dc circuit breaker on/off switch function by relay control contactor break-make.Its mechanical action is frequent, failure
Rate is high, and service life is short.During photovoltaic application, header box generally use 16 is into 1 and 10 into 1 two kind of form.Due to every remittance
Stream case concatenates the photovoltaic module of 16 or 10 branches respectively, and therefore, header box protection has the requirement of multiple branch circuit while detection.Tradition is converged
The photovoltaic branch for flowing case accelerates the heat of fuse tired equivalent to increase DC node using fuse due to the influence of day and night temperature
Labor effect, when fuse node poor contact, fusing time is elongated.It, can failure line in the case of this " not breaking disconnected "
The insulation of cable and fuse block, finally causes firing accident.Header box internal-flange bolt loosens, similar with its situation.
When earth fault occurs for direct current cables, the electric current flowed through on normal cable can pass through on photovoltaic DC-to-AC converter DC cabinet
" anti-to fill " arrives failure cable after busbar goes out confluence.The breaker for connecting photovoltaic DC-to-AC converter on failure cable is jumped since electric current is excessive
Lock.But the electric current of breaker does not increase in header box, at this point, header box equipment appearance ground connection pole tension is low, it is ungrounded
Pole tension is raised.This is a kind of hidden danger existing for photovoltaic generating system itself, and should give consideration can take measures to be controlled.
In view of above-mentioned defect, the positive research and innovation of the present inventor proposes a kind of header box protection dress being adapted to photovoltaic generating system
It sets, failure can be effectively prevented and further expanded.
Invention content
The object of the present invention is to provide a kind of header box protective device for capableing of the protection of multi-thread, multiple spot, effectively investigation, inspections
It surveys, the various circuit problems that control header box is likely to occur.
In order to achieve the above object, a kind of header box protective device is provided, the header box includes photovoltaic cable, direct current
Cable and breaker, the header box protective device include collecting unit, logic unit and execution unit；With
The voltage signal of the collecting unit acquisition direct current cables and the voltage signal of at least one photovoltaic cable branch road；
With
The logic unit includes at least two comparison modules in parallel, and comparison module is electrically connected with the collecting unit
It connects, one of comparison module receives the voltage signal on the direct current cables, other comparison modules receive the photovoltaic cable
The voltage signal of branch, comparison module include multiplication comparator component and diode, and multiplication comparator component accesses voltage letter
Number and comparison voltage, output end series diode, the output end of each diode access execution unit, the electricity of any comparison module
When signal being pressed to be greater than or equal to setting value with comparison voltage absolute value of the difference circuit breaker trip instruction is sent to the execution unit；
With
The execution unit be electrically connected with the logic unit and the instruction control transmitted according to the logic unit described in
Breaker open operation.
The multiplication comparator component is made of two multipliers and comparator in parallel, and described multiplier connects
Enter voltage signal, another multiplier accesses comparison voltage, the input terminal connection of the output end and comparator of two multipliers.
It is improved in the present invention to being directed to logic unit, main contrast carries out parallel connection, the i.e. input terminal of module compared with module
It is respectively connected to the voltage of acquisition, but output end collaborates.Collecting unit acquires multiple voltage values, this voltage value includes direct current cables
On voltage signal and photovoltaic cable on voltage signal, the voltage signal on one of comparison module access direct current cables,
Remaining comparison module access photovoltaic cable on voltage signal carry out logic judgment, when any comparison module voltage signal with than
When absolute value of the difference compared with voltage is greater than or equal to setting value, illustrates that short trouble occurs for cable, send and instruct to execution unit
To control breaker.
, it can be said that at least one comparison module and a ratio for photovoltaic cable monitoring for direct current cables monitoring
Can essentially be multiple comparison modules for photovoltaic cable monitoring in the present invention, type of attachment is still compared with module
Parallel connection is the monitoring that multi-route can be achieved in this way.
Preferably, further include guide wire；The collecting unit also acquires the voltage signal of photovoltaic DC-to-AC converter side；With
The logic unit further includes direct current cables fault identification module, and direct current cables identification module and comparison module are simultaneously
Connection, the direct current cables fault identification module receives the voltage signal of photovoltaic DC-to-AC converter side, voltage signal and ratio on direct current cables
Compared with voltage, the absolute value of the difference of voltage signal is more than the threshold of comparison voltage on the voltage signal and direct current cables of photovoltaic DC-to-AC converter side
When value, header box trip signal is exported, header box trip signal is sent to photovoltaic DC-to-AC converter by guide wire, controls photovoltaic inversion
The dc circuit breaker of device side trips.
Due to the case where voltage difference absolute value is greater than or equal to setting value on direct current cables, there are two kinds of possibility, i.e. direct current
Cable fault and photovoltaic DC-to-AC converter DC side failure, in order to identify that failure, the present invention are additionally arranged direct current cables fault identification module,
The voltage signal of photovoltaic DC-to-AC converter side, the signal on direct current cables is taken to make the difference and be compared with comparison voltage, to judge whether
It is direct current cables failure.When belonging to direct current cables failure, header box trip signal is exported, header box trip signal passes through guiding
Line is sent to photovoltaic DC-to-AC converter, the dc circuit breaker tripping of control photovoltaic DC-to-AC converter side.
Preferably, the logic unit further includes triode T3, receive direct current cables voltage signal comparison module in
The output end of multiplication comparator accesses the triode T3Collector, the direct current cables fault identification module output termination
Enter the triode T3Base stage, the triode T3Emitter be connected with guide wire, when photovoltaic DC-to-AC converter voltage signal with
The difference of voltage signal is more than the threshold value of comparator voltage on direct current cables, and receives the voltage signal of the comparison module of direct current cables
It sends and instructs to execution unit when being greater than or equal to setting value with comparison voltage absolute value of the difference.
Further, the logic unit further includes triode T2, three poles described in the signal of comparison module output in parallel
Pipe T2Collector, triode T3Emitter access triode T2Base stage, the triode T2Emitter connection guiding
Line.
Preferably, the guide wire is RS485 guide wires.
Preferably, the direct current cables fault identification module includes operational amplifier and comparator, the operation amplifier
Device accesses the voltage signal on the voltage signal and direct current cables of photovoltaic DC-to-AC converter side, and the input terminal of comparator is respectively connected to operation
The output end and comparison voltage of amplifier.
Further, the direct current cables fault identification module includes the positive DC cable identification module of parallel connection and bears
Pole direct current cables identification module, the positive DC cable identification module access on photovoltaic DC-to-AC converter side and direct current cables just
Voltage, the comparator output terminal in positive DC cable identification module access diode；It is identified with the negative DC cable
Module accesses the negative voltage on photovoltaic DC-to-AC converter side and direct current cables, and the comparator output terminal of negative DC cable identification module connects
Enter diode, on the voltage signal and direct current cables of the photovoltaic DC-to-AC converter side in any identification module the difference of voltage signal be more than than
Compared with voltage threshold value when, export header box trip signal.
Preferably, the logic unit further includes fuse identification module, and fuse identification module is in parallel with comparison module, described
Fuse identification module receives the voltage signal and comparison voltage of the voltage signal of direct current cables, photovoltaic cable, when direct current cables
The difference of the voltage signal of voltage signal and photovoltaic cable is more than comparison voltage, sends and instructs to the execution unit.
Fuse identification module is but also as bolt looseness identification module.
Preferably, the fuse identification module includes operational amplifier, comparator and diode, the operational amplifier
It is respectively connected to the voltage signal of photovoltaic DC-to-AC converter and the voltage signal of direct current cables, the comparator is respectively connected to operational amplifier
Output end and comparison voltage.
Further, the fuse identification module includes positive fuse identification module and cathode fuse identification mould in parallel
Block, the positive fuse identification module access the positive voltage of photovoltaic cable and direct current cables, and the cathode fuse identifies mould
Block accesses the negative voltage of photovoltaic cable and direct current cables, the voltage cable signal of the direct current of any identification module and photovoltaic cable
Difference is more than comparison voltage, sends and instructs to the execution unit.
Preferably, the voltage signal of the collecting unit acquisition direct current cables and the electricity of at least two photovoltaic cable branch roads
Press signal；With
The logic unit includes at least three comparison modules in parallel, and one of comparison module receives the direct current
Voltage signal on cable separately has at least two comparison modules to receive the voltage signal of the photovoltaic cable branch, receives optical cable
Each comparison module of branch voltage signal receives the voltage signal of respectively different photovoltaic cable branch road.
Further, the logic unit further includes fuse identification module, and the fuse identification module receives direct current cables
Voltage signal, comparison voltage and collecting unit acquisition at least two photovoltaic cables voltage signal, multiple photovoltaic cables
Operational amplifier and comparator are accessed after voltage signal series diode, when the voltage signal of direct current cables and the electricity of photovoltaic cable
It presses the difference of signal to be more than comparison voltage, sends and instruct to the execution unit.
Further, the logic unit further includes protection module, and the output signal access of comparison module in parallel is protected
Module connection is protected, protection module outputs signal to execution unit.
Preferably, the voltage signal U of the collecting unit acquisition direct current cableszAnd at least one photovoltaic cable branch road
Voltage signal Ui, photovoltaic is against electric appliance side voltage signal Um；With
Logic unit receive collecting unit acquisition to voltage signal Uz、Ui、UmAnd comparison voltage Uε1、Uε2、Uε3It carries out
Logical operation：
When satisfaction ((| UZ+-UZ-|>Uε1)and(Um-Uz>Uε3))or(|Ui+-Ui-|>Uε1)or(Ui-Uz＞ Uε2) when to execution
Unit, which is sent, executes signal；
The execution unit be electrically connected with the logic unit and the instruction control transmitted according to the logic unit described in
Breaker open operation, the execution unit, which includes gate pole, can cut-off thyristor.
Preferably, the collecting unit includes sequentially connected bleeder circuit, filter, voltage follower, photoelectricity coupling
Clutch and voltage-stabiliser tube.
The invention discloses a kind of scheme most having choosing, a kind of header box protective device, the header box includes photovoltaic electric
Cable, direct current cables and breaker, the header box protective device include collecting unit, logic unit and execution unit；With
The voltage signal of collecting unit acquisition direct current cables and the voltage signal of at least one photovoltaic cable branch road,
Photovoltaic is against electric appliance side voltage signal；With
The logic unit include at least two comparison modules, direct current cables fault identification module, fuse identification module,
One of comparison module receives the voltage signal on the direct current cables, other comparison modules receive the photovoltaic cable branch
Voltage signal, the direct current cables fault identification module receives voltage signal on direct current cables and photovoltaic DC-to-AC converter side
Voltage signal, the fuse identification module receive the voltage signal on voltage signal and photovoltaic cable on direct current cables, directly
The difference of voltage signal in galvanic electricity cable fault identification module on the voltage signal and direct current cables of direct current photovoltaic inverter side is more than
The threshold value of comparator voltage, and receive in the comparison module of direct current cables, the absolute value of the difference of voltage signal and comparison voltage is big
When setting value, high level signal is exported, the absolute value of the difference of voltage signal and comparison voltage is big in remaining comparator
In or be equal to setting value, export high level signal, the voltage signal of direct current cables is more than photovoltaic cable electricity in fuse identification module
When pressing signal, high level signal is exported；Thrin will be sent to execution unit and send instruction when being high level signal, described
Signed magnitude arithmetic(al) uses multiplication comparator component；With
The execution unit be electrically connected with the logic unit and the instruction control transmitted according to the logic unit described in
Breaker open operation.
A kind of header box guard method, includes the following steps：
With collecting unit acquisition direct current cables voltage signal Uz, at least one photovoltaic cable voltage signal Ui, photovoltaic inversion side
Voltage signal Um；
Logic unit receive collecting unit acquisition to voltage signal Uz, Ui, Um and comparison voltage Uε1、Uε2、Uε3It carries out
Logical operation：
When satisfaction ((| UZ+-UZ-|>Uε1)and(Um-Uz>Uε3))or(|Ui+-Ui-|>Uε1)or(Ui-Uz＞ Uε2) when to execution
Unit, which is sent, executes signal；
Execution unit controls the breaker open operation according to the instruction that the logic unit transmits.
Wherein, | UZ+-UZ-|>Uε1Operation and | Ui+-Ui-|>Uε1Operation using multiplication comparator component execute, or fortune
It calculates and is executed by diode in parallel, and operations are executed by triode.
The present invention is improved and has been supplemented to logic unit inside, has been carried out parallel processing to comparison module, has been compared mould
Block receives the voltage signal of photovoltaic cable and direct current cables respectively, logical operation is carried out by multiplication comparator component, when meeting
The signal of output signal when difference is more than or equal to comparison voltage absolute value, output is carried out the comparator of multichannel simultaneously by diode
Connection, reached any has signal output on the way, then is sent to execution unit, by execution unit control breaker combined floodgate,
Separating brake.
Logic unit in the present invention is additionally provided with fuse identification module and direct current cables fault identification module, is all made of acquisition
Voltage value carries out the mode of logical operation, and multi-class identification monitoring logic arithmetic element is formd inside logic unit, can
Timely processing and analysis are carried out to failure, there is preferable efficiency.
Beneficial effects of the present invention are：Enough identify multigroup optical crosstalk luff cable failure, direct current cables failure, fuse or bolt
Looseness fault.The error generated by method defect in traditional header box protection is avoided, while protective device is not by ambient light
According to the influence with environment temperature.Therefore, more can be based on safety in actual motion maintenance, in failure, protective device acts
It is sensitive, provide sound assurance for system security and stability.Moreover, this reduces the possibility of artificial investigation failure, reduce
The workload of practical operation maintenance personnel.
It should be understood that within the scope of the present invention, above-mentioned each technical characteristic of the invention and below in (such as embodiment)
It can be combined with each other between each technical characteristic specifically described, to form a new or preferred technical solution.As space is limited,
Not repeated them here.
Description of the drawings
Fig. 1 is header box under-voltage protection system structure diagram of the present invention；
Fig. 2 is the schematic diagram of collecting unit in the present invention；
Fig. 3 is the schematic diagram of logic unit in the present invention；
Fig. 4 is direct current cables failure schematic diagram of the present invention；
Fig. 5 is the schematic diagram of fuse failure in the present invention.
Specific implementation mode
Presently preferred embodiments of the present invention is described in detail below with reference to attached drawing, understands the present invention's to become apparent from
Objects, features and advantages.It should be understood that embodiment shown in the drawings does not limit the scope of the present invention, and it is only
Illustrate the connotation of technical solution of the present invention.
Term explanation
Header box：Header box main function is exactly that the input of photovoltaic array is carried out level-one confluence, for reducing photovoltaic battle array
Row are linked into the line of inverter, while providing lightning protection function, detect the operating status of photovoltaic panel, DC quantity state acquisition and disconnected
Road device state etc..
Photovoltaic DC-to-AC converter：Photovoltaic DC-to-AC converter is to connect resistance capacitance by power electronic devices (MOSFET, IGBT etc.), with
The direct current that header box transmission comes is transformed into alternating current, is completed at the same time by the break-make of the mode control device of pulse width modulation
The MPPT maximum power point tracking (MPPT) of photovoltaic module ensures intelligent control and anti-islanding effect etc..
Breaker：Designed coupling or uncoupling means can close, the electric current of break-make and carrying normal condition；And it can be non-
It under normal operating condition, can also be closed, disjunction and the conducting in certain time and break-make.
Gate level turn-off thyristor (GTO)：Gate level turn-off thyristor is a kind of derivation device of thyristor, can be passed through
Apply pulse current in gate pole and controls its break-make；Due to the voltage of the device, current capacity is larger, close with triode thyristor,
Therefore there can be more application in large-power occasions.
A kind of header box protective device, as shown in Figure 1, the header box includes photovoltaic cable 41,42, direct current cables 43,
44, breaker 60, collecting unit 10, logic unit 20 and execution unit 30.
Collecting unit 10 is used to acquire the voltage signal of direct current cables and photovoltaic cable branch road, and its principle is as shown in Figure 2,
The series connection of collecting unit 10 bleeder circuit 11, filter circuit 12, voltage follower 13, photoelectrical coupler 14 and voltage-stabiliser tube 15.UdcFor
DC voltage to be detected, the collected voltage signal of Hall voltage sensor make its voltage be limited in properly by bleeder circuit 11
Range；RC filters 12 filter out the noise in acquisition signal；Voltage follower 13 may insure output signal not by input electricity
The interference of the resistance on road is played the role of preventing voltge surge；Photoelectrical coupler 14 effectively realizes the electricity blocked between circuit
Contact, and the transmission of the signal between them is not cut off, isolation performance is good, stable and reliable in work not by Electromagnetic Interference；Voltage stabilizing
Pipe 15 is by output voltage UpotIt is limited in a certain range, plays the role of protecting circuit.
Logic unit 20 including multiple comparison modules 21, direct current cables fault identification module 22, fuse as shown in figure 3, know
Other module 23 and protection module 24.Each comparison module 21, direct current cables fault identification module 22 and fuse identification module 23 are in parallel,
Although input terminal received signal is different, single output end interflow access execution unit.Each comparison module 21 by operational amplification circuit,
Multiplication comparator component and diode composition.Each comparison module 21 difference lies in the voltage value of access difference, one of them
Comparison module 21 accesses the voltage U of direct current cablesz+And Uz-, remaining comparison module is respectively connected to U1+、U1-, U2+、U2-……
Un+、Un-.Wherein, operational amplification circuit is connected by two operational amplifiers, wherein an operational amplifier input signal be cable just
Pole and ground connection, by taking the comparator for accessing photovoltaic cable as an example, cable just extremely U1+, the output signal of the operational amplifier is input to
In another operational amplifier, another connecting pin and the cable cathode U of another operational amplifier1-Connection.Operational amplifier is operated in
Linear zone, the voltage U of operational amplifier outputa.Multiplication comparator component is by two analog multipliers and is connected to comparator and forms,
There are two input terminal and a leading-out terminals for analog multiplier.Same analog physical amount when input signal, output ammeter reach
Formula is：
Uc=kUε1 2
Ud=kUb 2=k (U1--U1+)2
Wherein k indicates scaling factor, and value is mostly 0.1V-1.Comparator in multiplier group is operated between inelastic region, defeated
Go out signal and there was only high level and low level.As signal UdMore than UcWhen, comparator A3Output voltage Ue=UOHSo that diode
D4Conducting, output voltage Uf=UOH；As signal UdLess than Uc, comparator output voltage U01=-UOHSo that diode D4Cut-off, it is defeated
Go out voltage Ue=0, export Uf=0.The multiplication comparator component of the present invention makes the difference of two squares of voltage signal and comparing voltage value
Judge, header box circuit breaker trip signal is exported when result is greater than or equal to setting value.Signal UdAccess diode D4.Compare
Voltage is equal to 380V-400V and setting value is equal to 190V-320V.For receiving direct current cables voltage Uz+And Uz-Comparison mould
Block 21, structure are also identical, and the parallel relationship between multiple comparison modules 21 is mainly collaborated by the output end of diode
Output signal, as long as the output high level signal of any one comparison module, then be output to execution unit by high level signal.
Logic unit 20 further includes direct current cables fault identification module 22, it includes positive DC cable identification module and is born
Difference lies in described for pole direct current cables identification module, positive DC cable identification module and negative DC cable identification module
Positive DC cable identification module access photovoltaic DC-to-AC converter side and positive voltage on direct current cables and negative DC electricity
Cable identification module accesses the negative voltage on photovoltaic DC-to-AC converter side and direct current cables.Two direct current cables identification modules include operation
Amplifier, comparator and diode, operational amplifier access the voltage signal of direct current cables and the voltage letter of photovoltaic DC-to-AC converter side
Number, by taking positive DC cable identification module as an example, operational amplifier accesses Um+And Uz+, opamp-output signal access ratio
Compared in device, another arrival end of comparator accesses the threshold value U comparedε3, the output end access diode of comparator, any identification module
In photovoltaic DC-to-AC converter side voltage signal and direct current cables on voltage signal difference be more than comparison voltage threshold value when, output converge
Flow case trip signal.
The logical schematic of direct current cables fault identification module 22 is as shown in figure 4, work as the direct current cables of collecting unit acquisition
Voltage UZ+、UZ-The size for comparing the two by comparing device, meets inequality | UZ+-UZ-|>Uε1When, it is possible to determine that it is direct current cables
Failure, such as fault point f1Or photovoltaic DC-to-AC converter DC side failure, such as fault point f2。l1For fault point f1To confluence l1The distance of case,
l2For fault point f1To the distance of photovoltaic DC-to-AC converter, the overall length of l direct current cables between header box and photovoltaic DC-to-AC converter.The present invention
Compare the direct current cables voltage of header box side by comparing device and the direct current cables voltage of photovoltaic DC-to-AC converter side identifies direct current
Cable fault and photovoltaic DC-to-AC converter DC side failure.
Under photovoltaic DC-to-AC converter DC side failure, the electric current flowed through on direct current cables is I.Due to photovoltaic module opto-electronic conversion
Particularity, the size and the value under normal operating condition of the current value are not much different.Header box side and photovoltaic DC-to-AC converter side electricity
Cable voltage is respectively Um、UzFunctional relation meet expression formula (1)：
Um-Uz=lIR (1)
R is the resistance of element length direct current cables in formula.
Since cable length l is little, expression formula Um-UzVery little can be less than threshold voltage Uε3。
|Um-Uz|<Uε3 (2)
When earth fault occurs for direct current cables, all electric currents flowed through can pass through on DC cabinet on normal direct current cables
" anti-to fill " arrives failure cable after busbar goes out confluence.
Header box side and photovoltaic DC-to-AC converter side voltage cable are respectively Um、UnFunctional relation meet expression formula (2)
Um-Uz=l1I1R-l2I2R (3)
At this point, anti-sink current value I2Size by other parallel connection header box in square formation the summation for flowing through electric current.
|Um-Uz|>Uε3 (4)
Direct current cables failure and photovoltaic DC-to-AC converter DC side failure are identified according to formula (2) and formula (4).Work as direct current cables
When failure, header box circuit breaker trip, and header box trip signal is passed to by RS485 connections.The emphasis of the present invention exists
In studying a kind of protection system of photovoltaic combiner box, photovoltaic DC-to-AC converter DC side failure is not belonging to the content that the present invention studies, no
Illustrate herein.
Direct current cables identification module 22 passes through triode T3It is connect with the comparison module of direct current cables, receives direct current cables electricity
The output end of the multiplication comparator component in the comparison module of signal is pressed to access the triode T3Collector, the direct current
The output end of cable fault identification module accesses the base stage of the triode T3, and T3 emitters connect the diode in comparison module.
Construction and equipment quality are also an important factor for influencing photovoltaic power station power generation.The use of fuse and bolt increases directly
Node is flowed, is hidden some dangers for safely for the O＆M in power station.Fuse block and bolt are high to cable construction quality requirement, often contact
Bad phenomenon causes header box arcing or burns phenomenon.When due to poor contact, it is equivalent at node and has concatenated an electricity
Resistance, as Fig. 4 shows.Therefore fuse identification module is set in logic unit, fuse identification module is with bolt looseness identification module
Identical meanings.Fuse identification module 23 includes the positive fuse identification module and cathode fuse identification module of parallel connection, positive fuse
Difference lies in, positive fuse identification module access photovoltaic cable and direct current cables for identification module and cathode fuse identification module
Positive voltage, cathode fuse identification module access the negative voltage of photovoltaic cable and direct current cables, and the fuse identification module includes
Operational amplifier, comparator and diode, by taking positive fuse identification module as an example, U1+、U2+……UnIt is in parallel after series diode
Enter operational amplifier, the output end of operational amplifier accesses comparator, and comparator also accesses comparison voltage Uε2, the output of comparator
Terminate the direct current that positive or negative pole identification module is realized into diode voltage cable signal be more than with the difference of photovoltaic cable compared with
Voltage sends to the execution unit and instructs.Principle such as Fig. 5, UkFor the voltage of photovoltaic cable, UlFor direct current cables voltage.Its
In, UkWith UlRelational expression be：
Uk-Ul=IR (5)
Compare photovoltaic cable by comparing device and direct current cables voltage difference meets inequality Uk-Ul>Uε2, to identify fuse
Or the loosening of bolt, to control dc circuit breaker tripping.
The output end of each diode of the direct current cables identification module 22, comparison module 21 and fuse identification module 23
Interflow output, connection protection circuit 24, protection circuit 24 are connect with execution unit.
Wherein, logic unit further includes triode T2, triode T described in the signal of comparison module output in parallel2Current collection
Pole, triode T3Emitter access triode T2Base stage, the triode T2Emitter connect guide wire.Guide wire 70
For RS485 guide wires.
Execution unit, which includes control gate pole, can cut-off thyristor.
Voltage protection system is divided to realize that dc circuit breaker closes by relay control contactor break-make in the prior art
Lock function.The present invention can cut-off thyristor using gate pole, so that DC current is started from scratch steady rising, can not only realize circuit
System without deaerator, and can prevent electric current in the spring coil in breaker and voltage during the control caused by mistake
Voltage.Therefore, control system of the invention be active in one's movements, stability it is strong.
When logic unit output signal switching signal 001, sub-gate signal 002, respective gate pole can cut-off thyristor injection
Gate current Ig, gate pole can cut-off thyristor and be in forward bias, and anode current is with IGIncrease and gradually increase, until gate pole
Thyristor can be cut-off and enter conducting state.Conventionally used relay control contactor break-make realizes dc circuit breaker on/off switch
In the process, the coil in relay is damaged since dash current is excessive, needed between relay and contactor exist be electrically connected, therefore
Barrier rate is high.The shortcomings that the present invention overcomes relays, during dc circuit breaker on/off switch, DC current is started from scratch steadily
Rise, can not only realize the system without deaerator of circuit, and the electric current in the spring coil in breaker and electricity can be prevented
It is pressed in overvoltage caused by control in the process.
Presently preferred embodiments of the present invention has already been described in detail above, it is understood that understanding the above-mentioned of the present invention reading
After lecturing content, those skilled in the art can make various modifications or changes to the present invention, and such equivalent forms are equally fallen within
The scope of the appended claims of the present application.
Claims (9)
1. a kind of header box protective device, the header box includes photovoltaic cable, direct current cables and breaker, which is characterized in that
The header box protective device includes collecting unit, logic unit and execution unit；With
The voltage signal of the collecting unit acquisition direct current cables and the voltage signal of at least one photovoltaic cable branch road；With
The logic unit includes at least two comparison modules in parallel, and comparison module is electrically connected with the collecting unit,
In a comparison module receive the voltage signal on the direct current cables, other comparison modules receive the photovoltaic cable branch
Voltage signal, comparison module include multiplication comparator component and diode, multiplication comparator component access voltage signal and
The output end of comparison voltage, output end series diode, each diode accesses execution unit, the voltage signal of any comparison module
When being greater than or equal to setting value with comparison voltage absolute value of the difference circuit breaker trip instruction is sent to the execution unit；With
The execution unit is electrically connected with the logic unit and controls the open circuit according to the instruction that the logic unit transmits
Device separating brake；
The multiplication comparator component is made of two multipliers in parallel and a comparator, and the multiplier described in one connects
Enter voltage signal, another multiplier accesses comparison voltage, the input terminal connection of the output end and comparator of two multipliers；
It further include guide wire；
The collecting unit also acquires the voltage signal of photovoltaic DC-to-AC converter side；With
The logic unit further includes direct current cables fault identification module, and direct current cables fault identification module and comparison module are simultaneously
Connection, the direct current cables fault identification module receives the voltage signal of photovoltaic DC-to-AC converter side, voltage signal and ratio on direct current cables
Compared with voltage, the absolute value of the difference of voltage signal is more than the threshold of comparison voltage on the voltage signal and direct current cables of photovoltaic DC-to-AC converter side
When value, header box trip signal is exported, header box trip signal is sent to photovoltaic DC-to-AC converter by guide wire, controls photovoltaic inversion
The dc circuit breaker of device side trips.
2. header box protective device according to claim 1, which is characterized in that the logic unit further includes triode T3,
The output end for receiving the multiplication comparator component in the comparison module of direct current cables voltage signal accesses the triode T3Collection
The output end of electrode, the direct current cables fault identification module accesses the triode T3Base stage, the triode T3Transmitting
Pole is connected with guide wire, when the difference of voltage signal on the voltage signal and direct current cables of photovoltaic DC-to-AC converter is more than comparator voltage
Threshold value, and when voltage signal and the comparison voltage absolute value of the difference for receiving the comparison module of direct current cables are greater than or equal to setting value
It sends and instructs to execution unit.
3. header box protective device according to claim 2, which is characterized in that the logic unit further includes triode T2,
The signal of comparison module output in parallel accesses the triode T2Collector, triode T3Emitter access triode T2
Base stage, the triode T2Emitter connect guide wire.
4. header box protective device according to claim 2, which is characterized in that the direct current cables fault identification module
Including operational amplifier and comparator, on the voltage signal and direct current cables of operational amplifier access photovoltaic DC-to-AC converter side
The input terminal of voltage signal, comparator is respectively connected to the output end and comparison voltage of operational amplifier.
5. header box protective device according to claim 1, which is characterized in that the logic unit further includes fuse identification
Module, fuse identification module is in parallel with comparison module, and the fuse identification module receives voltage signal, the photovoltaic electric of direct current cables
The voltage signal and comparison voltage of cable, when the voltage signal and photovoltaic cable of direct current cables voltage signal difference be more than it is more electric
Pressure sends to the execution unit and instructs.
6. header box protective device according to claim 1, which is characterized in that
The voltage signal of the collecting unit acquisition direct current cables and the voltage signal of at least two photovoltaic cable branch roads；With
The logic unit includes at least three comparison modules in parallel, and one of comparison module receives the direct current cables
On voltage signal, separately there are at least two comparison modules to receive the voltage signal of the photovoltaic cable branch, receive photovoltaic cable
Each comparison module of branch voltage signal receives the voltage signal of respectively different photovoltaic cable branch road.
7. header box protective device according to claim 1, which is characterized in that the collecting unit acquisition direct current cables
Voltage signal UzAnd at least one photovoltaic cable branch road voltage signal Ui, photovoltaic DC-to-AC converter side voltage signal Um；With
Logic unit receives the voltage signal U of collecting unit acquisitionz、Ui、UmAnd comparison voltage Uε1、Uε2、Uε3Carry out logic fortune
It calculates：
When satisfaction ((| UZ+-UZ-|>Uε1)and(Um-Uz>Uε3))or(|Ui+-Ui-|>Uε1)or(Ui-Uz＞ Uε2) when to execution unit
It sends and executes signal；
The execution unit is electrically connected with the logic unit and controls the open circuit according to the instruction that the logic unit transmits
Device separating brake, the execution unit, which includes gate pole, can cut-off thyristor.
8. header box protective device according to claim 1, which is characterized in that the collecting unit includes being sequentially connected
Bleeder circuit, filter, voltage follower, photoelectrical coupler and voltage-stabiliser tube.
9. a kind of header box guard method, using header box protective device as described in any of the claims 1 to 8, including it is as follows
Step：
With collecting unit acquisition direct current cables voltage signal Uz, at least one photovoltaic cable voltage signal Ui, photovoltaic DC-to-AC converter side electricity
Press signal Um；
Logic unit receives the voltage signal U of collecting unit acquisitionz、Ui、UmAnd comparison voltage Uε1、Uε2、Uε3Carry out logic fortune
It calculates：
When satisfaction ((| UZ+-UZ-|>Uε1)and(Um-Uz>Uε3))or(|Ui+-Ui-|>Uε1)or(Ui-Uz＞ Uε2) when to execution unit
It sends and executes signal；
Execution unit controls the breaker open operation according to the instruction that the logic unit transmits.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201611085854.XA CN106655086B (en) | 2016-11-30 | 2016-11-30 | A kind of header box protective device and method |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201611085854.XA CN106655086B (en) | 2016-11-30 | 2016-11-30 | A kind of header box protective device and method |
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| CN106655086B true CN106655086B (en) | 2018-09-14 |
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| CN109669062A (en) * | 2017-10-17 | 2019-04-23 | 许继集团有限公司 | A kind of automatic detection elastic test macro of bolt |
| CN111525517B (en) * | 2020-04-14 | 2022-07-22 | 西安许继电力电子技术有限公司 | Method and system for suppressing overvoltage of converter valve submodule |
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| CN204272011U (en) * | 2014-10-23 | 2015-04-15 | 安徽四创电子股份有限公司 | A kind of solar photovoltaic water pump control system |
| CN105429115A (en) * | 2015-12-14 | 2016-03-23 | 深圳威能技术有限公司 | Photovoltaic power generation system, photovoltaic direct current cable protection device and control method thereof |
| CN205509468U (en) * | 2015-12-30 | 2016-08-24 | 中国电力工程顾问集团华东电力设计院有限公司 | Collection flow box protection device |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| US8508896B2 (en) * | 2010-11-09 | 2013-08-13 | Eaton Corporation | DC feeder protection system |
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN204272011U (en) * | 2014-10-23 | 2015-04-15 | 安徽四创电子股份有限公司 | A kind of solar photovoltaic water pump control system |
| CN105429115A (en) * | 2015-12-14 | 2016-03-23 | 深圳威能技术有限公司 | Photovoltaic power generation system, photovoltaic direct current cable protection device and control method thereof |
| CN205509468U (en) * | 2015-12-30 | 2016-08-24 | 中国电力工程顾问集团华东电力设计院有限公司 | Collection flow box protection device |
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