Utility model content
Main purpose of the present utility model is to propose a kind of resisting potential induced degradation device for photovoltaic generating system,
Aim to solve the problem that the positive direct-current bus of inverter or the positive pole of PV components hinder for some reason appearance ground connection, cause the positive and negative extremely short of PV components
Road, causes fuse frequent breakage, increases the problem of maintenance workload.
For achieving the above object, this utility model embodiment provides a kind of anti-potential induction for photovoltaic generating system and declines
Subtract device, the photovoltaic generating system includes PV components, and connects with the PV components by positive direct-current bus, negative dc bus
The inverter for connecing;One end of the resisting potential induced degradation device is connected with negative dc bus, other end ground connection;The device includes
Electrical switch, fuse and the current-limiting resistance being connected in series, the device also includes detection module, comparison module, electrical switch control
Molding block and monitoring module;
The detection module, for detecting the voltage at current-limiting resistance two ends or flowing through the electric current of current-limiting resistance;
The comparison module, for the voltage that detected according to the detection module or electric current, with default voltage or
Person's electric current is compared, and generates the control signal of electrical switch first to the electrical switch control module;
The monitoring module, controls for according to the system information of the photovoltaic generating system, generating electrical switch second
Signal gives the electrical switch control module;
The electrical switch control module, for the control signal of electrical switch first that generated according to the comparison module and
The control signal of electrical switch second that the monitoring module is generated, controls shut-off or the closure of the electrical switch.
Optionally, described device includes the DC voltage being connected in series with the electrical switch, fuse, current-limiting resistance
Source.
Optionally, the direct voltage source includes isolating transformer and rectification unit;
The input of the isolating transformer is connected with the ac output end of the inverter;The isolating transformer it is defeated
Go out end to be connected with the rectification unit.
Optionally, the rectification unit includes commutation diode and filter capacitor.
Optionally, the direct voltage source includes DC-DC converter;
The input of the DC-DC converter is connected with the direct-flow input end or PV components of the inverter.
Optionally, the detection module includes high resistant Differential Detection module;The high resistant Differential Detection module, for obtaining
The voltage at current-limiting resistance two ends.
Optionally, the detection module includes Hall detection module;One end of the current-limiting resistance is provided with Hall unit device
Part, by the Hall components and parts and the Hall detection module electric current of current-limiting resistance is obtained.
Optionally, the system information of the photovoltaic generating system includes the compressor start up condition and/or the light of the inverter
The insulation impedance detection information of photovoltaic generating system.
Optionally, the electrical switch includes the one kind in IGCT, transistor, IGBT or field effect transistor.
Optionally, the PV components include the multiple PV batteries being connected in series or multiple PV batteries for being connected in parallel or
One kind in multiple PV batteries of person's connection in series-parallel connection.
The resisting potential induced degradation device for photovoltaic generating system that this utility model embodiment is provided, by what is arranged
Detection module, comparison module, electrical switch control module and monitoring module, can in time detect PV in photovoltaic generating system
The situation of component positive pole shorted to earth, and the connection of resisting potential induced degradation device and negative dc bus can be quickly shut off,
The fuse of resisting potential induced degradation device and the damage of resistance are prevented, while the information of insulation impedance failure can be reported in time, is dropped
The low workload of system maintenance.
Specific embodiment
It should be appreciated that specific embodiment described herein is not used to limit this only to explain this utility model
Utility model.
This utility model each embodiment is realized referring now to Description of Drawings.In follow-up description, using being used for
Represent the suffix of such as " module ", " part " or " unit " of element only for being conducive to explanation of the present utility model.
As shown in Figures 2 and 3, this utility model embodiment proposes that a kind of anti-potential induction for photovoltaic generating system declines
Subtract device, photovoltaic generating system includes PV components 10, and connects with PV components 10 by positive direct-current bus 21, negative dc bus 22
The inverter 40 for connecing;One end of resisting potential induced degradation device 30 is connected with negative dc bus 22, other end ground connection;Anti- potential is lured
Lead electrical switch 31, fuse 32 and current-limiting resistance 33 that attenuating device 30 includes being connected in series.It should be noted that series connection connects
Electrical switch 31, fuse 32 and the current-limiting resistance 33 for connecing, the order of connection relation between device is not limited by accompanying drawing.
In the present embodiment, PV components 10 can be the multiple PV batteries 11 being connected in series or the multiple PV being connected in parallel
Battery 11 or multiple PV batteries 11 of connection in series-parallel connection.
Refer to shown in Fig. 3, resisting potential induced degradation device 30 also includes detection module, comparison module, electrical switch control
Molding block and monitoring module;
Detection module, for detecting the voltage at current-limiting resistance two ends or flowing through the electric current of current-limiting resistance;
In the present embodiment, detection module may include high resistant Differential Detection module, can be real by high resistant Differential Detection module
When obtain the voltage at current-limiting resistance 33 two ends.
In the present embodiment, detection module may include Hall detection module, and one end of current-limiting resistance 33 is provided with Hall unit
Device, by Hall components and parts and Hall detection module the electric current at the two ends of current-limiting resistance 33 can be in real time obtained.
It should be noted that using high resistant Differential Detection module or Hall detection module, can be by user according to actual feelings
Condition is selected.
Comparison module, for the voltage that detected according to detection module or electric current, enters with default voltage or electric current
Row compares, and generates electrical switch the first control signal electron switch control module;
In the present embodiment, comparison module can be a comparator circuit, the voltage for detecting or electric current after filtering after
The in-phase end of comparator is sent to, default threshold voltage accesses the backward end of comparator, when the voltage for detecting is higher than threshold values electricity
After pressure, comparator output high level, as the first control signal of electrical switch.
Monitoring module, for according to the system information of photovoltaic generating system, generating the control signal of electrical switch second to electricity
Sub- switch control module;In the present embodiment, the compressor start up condition of the system information of photovoltaic generating system including inverter 40 and/or
The insulation impedance detection information of photovoltaic generating system.
In the present embodiment, monitoring module can be the DSP control system of inverter, when system does not have insulation impedance failure,
After inverter startup operation, DSP sends high level as the second control signal of electrical switch, otherwise sends low level as electricity
Second control signal of son switch.
In the present embodiment, monitoring module is alternatively the monitoring system of photovoltaic generating system or for an independent module.
Electrical switch control module, for the control signal of electrical switch first that generated according to comparison module and monitoring module
The control signal of electrical switch second of generation, controls shut-off or the closure of electrical switch.First control signal of electrical switch
After being negated by gate, carry out gate line and calculate with the second control signal of electrical switch, if line is defeated with after
Go out then to control electrical switch 31 for high level and turn on, otherwise control electrical switch 31 and disconnect.
In the present embodiment, electrical switch includes but is not limited to IGCT, transistor, IGBT or field effect transistor.
Refer to shown in Fig. 4, further, resisting potential induced degradation device 30 include be connected in series electrical switch 31,
Fuse 32, current-limiting resistance 33 and direct voltage source 34.Direct voltage source 34 is used to raise the negative dc bus of PV components to big
The voltage on ground.
Refer to shown in Fig. 5, direct voltage source may include isolating transformer T1 and rectification unit, rectification unit includes rectification
Diode D1 and filter capacitor C1.The input of isolating transformer T1 is connected with the ac output end 41 of inverter 40;Isolation becomes
The outfan of depressor T1 is connected with rectification unit.
In other embodiments, direct voltage source may include DC-DC converter, the input and inverter of DC-DC converter
40 direct-flow input end (i.e. positive direct-current bus 21, negative dc bus 22) or PV components connection 10.
For a better understanding of the present invention thought, is set forth in reference to Fig. 6.The positive and negative terminal of PV batteries is to its side
All there is distribution capacity and DC impedance in frame (i.e. greatly), after polylith PV battery series-parallel connections connect, the distribution capacity to the earth
The uf orders of magnitude can be reached, only tens K Europe can be reduced to the DC impedance of the earth.In resisting potential induced degradation device 30
After the conducting closure of electrical switch 31, positive direct-current bus 21, negative dc bus 22, current-limiting resistance 33, direct voltage source 34 and PV groups
The D.C. resistance electric capacity of part 10 forms the equivalent circuit shown in Fig. 6.In figure Upv for inverter 40 DC input voitage (i.e. just
Voltage between dc bus and negative dc bus), C+, C- are respectively equivalent point over the ground of positive direct-current bus, negative dc bus
Cloth electric capacity, R+, R- are respectively positive direct-current bus, negative dc bus Equivalent DC impedance over the ground, and R is resisting potential induced degradation dress
The impedance of 30 current-limiting resistance 33 is put, U is the direct voltage source 34 of resisting potential induced degradation device 30, and due to PV components 10
Symmetry, C+ and C- is equal, and R+ and R- are equal, therefore can be calculated voltage of the negative dc bus (Udc-) to the earth (O)
For
In order to reach the effect of resisting potential induced degradation, Udc- needs to meet Udc- >=0, that is, need to design anti-potential induction
Direct voltage source 34 meets voltage relationship in attenuating device 30:
There is no the shorted to earth of PV components 10 under normal circumstances, by the electric current of resisting potential induced degradation device 30
For:I≤U/R
Electrical switch 31, fuse 32 and the current limliting electricity of resisting potential induced degradation device 30 are selected according to this current value size
The rated current tolerance parameter of resistance 33.
After the positive pole for PV components 10 occur is to the earth PE short circuit unusual service conditions, by resisting potential induced degradation device 30
Maximum current is:
Electrical switch 31, fuse 32 and the current limliting electricity of resisting potential induced degradation device 30 are selected according to this current value size
The maximum current tolerance parameter of resistance 33.
After the positive pole of PV components 10 in system short-circuit abnormal conditions occurs to the earth PE, failure is detected in time, and pass through
The fast shut-off resisting potential induced degradation device 30 of electrical switch 31 and the connection of negative dc bus 22, prevent resisting potential induced degradation
The fuse 32 of device 30 and the damage of current-limiting resistance 33, while reporting the information of insulation impedance failure.
By taking Fig. 4 as an example, electrical switch 31 may be selected 1200V it is pressure/the field effect metal-oxide-semiconductor of 10A rated current, fuse 32
Rated current be 1A, the voltage of direct voltage source 34 is 50Vdc.If the photovoltaic generating system of photovoltaic generating system 1000V, i.e.,
Upv is 1000V, it is assumed that R+ is 5k Europe, and resistance R of current-limiting resistance 33 is 100 Europe, the equivalent circuit according to Fig. 6, Ke Yiji
Calculate and now bear voltage Udc-=29V of the dc bus to the earth, meet the requirement of resisting potential induced degradation design.There is no PV
Component shorted to earth under normal circumstances, by electric current I=(the 50-29)/100=0.21A of resisting potential induced degradation device 30,
The voltage at the two ends of current-limiting resistance 33 also all meets requirement for the type selecting of 21V, power consumption 4.4W, fuse 32 and electrical switch 31.
Meet inverter compressor start up condition when monitoring module detects photovoltaic generating system, and receive photovoltaic generating system
Insulation impedance detection information it is normal after, send closure electrical switch 31 request;Otherwise send and disconnect asking for electrical switch 31
Ask.Electrical switch control module receives the signal of monitoring module and comparison module and does Comprehensive Control, if monitoring module and compared
Module all asks to close electrical switch 31, then perform the order of closure electrical switch 31, otherwise disconnects the conducting of electrical switch 31.
It is of different sizes according to the different short circuit currents for occurring of short dot after occurring in PV components 10 to big ground short circuit,
Maximum short circuit current be inverter positive direct-current bus to big ground short circuit when.The voltage at the two ends of real-time sampling current-limiting resistance 33 is sent to height
Resistance Differential Detection module, then the voltage for detecting is compared judgement with default voltage.If more than threshold values, compares mould
Block then sends the request for disconnecting electrical switch 31 to electrical switch control module;If being not above threshold values, closure electricity is sent
The request of son switch 31.Simultaneously electrical switch control module can be monitored whether the feedback of the information of threshold values is exceeded to monitoring module
Module can report and submit the information of the insulation impedance failure of photovoltaic generating system, and electron to open after the information more than threshold values is received
Close control module and send the request for disconnecting electrical switch 31, form lock-in control.
The resisting potential induced degradation device for photovoltaic generating system that this utility model embodiment is provided, by what is arranged
Detection module, comparison module, electrical switch control module and monitoring module, can in time detect PV in photovoltaic generating system
The situation of component positive pole shorted to earth, and the connection of resisting potential induced degradation device and negative dc bus can be quickly shut off,
The fuse of resisting potential induced degradation device and the damage of resistance are prevented, while the information of insulation impedance failure can be reported in time, is dropped
The low workload of system maintenance.
Preferred embodiment of the present utility model is these are only, the scope of the claims of the present utility model is not thereby limited, it is every
The equivalent structure made using this utility model description and accompanying drawing content or equivalent flow conversion, or be directly or indirectly used in
Other related technical fields, are included in the same manner in scope of patent protection of the present utility model.