Background technology
Potential induction attenuation (PID, Potential Induced Degradation) refers to: because high pressure is applied to the phenomenon that cell panel makes its performance reduce over the ground.According to different cell panel characteristics, this high pressure may be positive voltage, also may be negative voltage.
The phenomenon that PID causes cell panel performance to reduce is: degradation under open circuit voltage decline (Voc), breaking current (Isc) fill factor, curve factor (FF).
SUNPOWER company of famous American photovoltaic manufacturer finds, adopts backplane contact high-efficiency battery sheet A-300, specifically on assembly, applies a high back voltage, Surface Polarization phenomenon occurs.If apply the positive voltage relative to the earth on assembly, leakage current can flow to ground from battery immediately.The surface of battery can along with accumulated time negative electrical charge, and positive charge can be attracted to battery surface by these electric charges, forms complex centre.On the contrary, when assembly applying negative voltage, polarization phenomena are corresponding change also, and the performance of assembly does not have impact in this case.
In recent years, along with the development of large-scale power station, mainly near the power station of coastal area, the environmental condition in these areas is relatively more severe, such as, and high temperature, high humidity etc.Along with the prolongation of time, PID problem is more and more serious.
Three-phase alternating current for current transformer exports the photovoltaic generating system being connected electrical network by solar cell serial (transformer has primary side, primary side and the neutral terminal in primary side), by the current potential of the neutral terminal that controls transformer in electricity generation system (PE) over the ground, PID problem can be solved.But owing to containing multiple current transformer in this type of photovoltaic generating system, each current transformer needs extraction N line to be connected with the neutral terminal of solar cell serial, add system cost and line loss, and increase wiring complexity, and can system reliability be reduced.And for not possessing the photovoltaic generating system of transformer of neutral terminal, the program is inapplicable.
Therefore, solving the problem of the hydraulic performance decline that potential induction attenuation is brought to assembly, is those skilled in the art's technical issues that need to address.
Summary of the invention
The technical problem that the application will solve is to provide a kind of voltage compensating device, current transformer and the photovoltaic generating system that solve potential induction attenuation, can solve the assembly property decline problem that PID causes.
This application provides a kind of photovoltaic generating system, comprise the current transformer that at least one has direct-flow input end and ac output end, the solar cell tandem that be electrically connected corresponding to the direct-flow input end of described current transformer, solar cell serial, the ac output end of described current transformer is in parallel, described solar cell tandem comprises at least one solar panel, described solar cell serial comprises primary side and primary side, the ac output end of described primary side and current transformer is electrically connected, described photovoltaic generating system also comprises: neutral line device, the primary side of the first end of described neutral line device and the ac output end of described current transformer and described solar cell serial is electrically connected, voltage compensating device, between the second end that described voltage compensating device is connected to described neutral line device and ground, controls the current potential of the second end of described neutral line device by the output voltage controlling described voltage compensating device.
Further, described neutral line device comprises three non-polar electric capacity, and one end of described electric capacity links together as the second end of described neutral line device, and the other end of described electric capacity is connected with three of the ac output end of described current transformer respectively.
Further, described neutral line device comprises three resistance, and one end of described resistance links together as the second end of described neutral line device, and the other end of described resistance is connected with three of the ac output end of described current transformer respectively.
Further, described voltage compensating device comprises: input unit, for from the power taking of described solar cell tandem, or, from solar cell serial primary side or primary side power taking; Voltage transformation module, sends to output unit after the voltage for being obtained by described input unit converts; Output unit, described output unit is connected with the second end of described neutral line device, for the Voltage Feedback that converted by described voltage transformation module to the second end of described neutral line device to control the current potential of the second end of neutral line device.
Further, described input unit is from the primary side of solar cell serial or primary side power taking, and described voltage transformation module comprises three-phase main-frequency transformer, rectifier bridge, a DC/DC converter; The primary side of described three-phase main-frequency transformer connects primary side or the primary side of solar cell serial, described rectifier bridge is connected between the primary side of three-phase main-frequency transformer and the input of a DC/DC converter, described rectifier bridge is used for converting the alternating current of the primary side of three-phase main-frequency transformer to direct current and is supplied to a DC/DC converter, and the described output of a DC/DC converter is connected with the second end of neutral line device.
Further, described input unit is specially from solar cell serial primary side or primary side power taking:
Input unit is from the line voltage of solar cell serial primary side or phase voltage power taking; Or input unit is from the line voltage of solar cell serial primary side or phase voltage power taking.
Further, described input unit is from the power taking of described solar cell tandem, described voltage transformation module comprises the 2nd DC/DC converter, the input of described 2nd DC/DC converter is connected with described solar cell tandem, and the described output of the 2nd DC/DC converter is connected with the second end of neutral line device.
Further, described voltage compensating device be described at least one there is the part of any one current transformer in the current transformer of direct-flow input end and ac output end.
The application also provides a kind of voltage compensating device, consistent with the voltage compensating device in above-mentioned photovoltaic generating system.
The application also provides a kind of current transformer being applied to above-mentioned photovoltaic generating system, comprises above-mentioned voltage compensating device.
Compared with prior art, the application has the following advantages:
The photovoltaic generating system that the application provides, comprises neutral line device and voltage compensating device, and in the first end of described neutral line device and photovoltaic generating system, the ac output end of current transformer and the primary side of solar cell serial are electrically connected; Between the second end that described voltage compensating device is connected to described neutral line device and ground, controlled the current potential of described neutral line device by the output voltage controlling described voltage compensating device.Compared with prior art, the voltage compensating device that the application provides and current transformer work simultaneously, the current potential of neutral line device is controlled by the output voltage of control voltage compensation arrangement, avoid multiple stage current transformer all to need to draw N line to be connected with the neutral terminal of solar cell serial, thus reducing system cost and line loss, scheme is simple; And be applicable to the photovoltaic generating system of the transformer not possessing neutral terminal.When containing multiple current transformer in photovoltaic generating system, only this neutral line device and voltage compensating device need be set at the ac output end of a current transformer, can reach all current transformers in elimination system connect the PID impact of photovoltaic group string, thus useful life of all photovoltaic modulies in raising system.
Embodiment
For enabling above-mentioned purpose, the feature and advantage of the application more become apparent, be described in detail below in conjunction with the embodiment of accompanying drawing to the application.
See Fig. 1, this figure is photovoltaic generating system embodiment one schematic diagram that the application provides.
The present embodiment provides a kind of photovoltaic generating system, comprise the current transformer 120 that at least one has direct-flow input end and ac output end, the solar cell tandem 110 that be electrically connected corresponding to the direct-flow input end of described current transformer 120, solar cell serial 130, neutral line device 150 and voltage compensating device 140, the ac output end of described current transformer 120 is in parallel, described solar cell tandem 110 comprises at least one solar panel, described solar cell serial 130 comprises primary side 131 and primary side 132, described primary side 131 is electrically connected with the ac output end of current transformer, the primary side 131 of the first end of described neutral line device 150 and the ac output end of described current transformer 120 and described solar cell serial 130 is electrically connected, between the second end that described voltage compensating device 140 is connected to described neutral line device 150 and ground, the current potential of the second end of described neutral line device 150 is controlled by the output voltage controlling described voltage compensating device 140.
The photovoltaic generating system that the application provides, comprises neutral line device and voltage compensating device, and in the first end of described neutral line device and photovoltaic generating system, the ac output end of current transformer and the primary side of solar cell serial are electrically connected; Second end of described voltage compensating device and described neutral line device is electrically connected, and is controlled the current potential of described neutral line device by the output voltage controlling described voltage compensating device.Compared with prior art, the voltage compensating device that the application provides and current transformer work simultaneously, the current potential of neutral line device is controlled by the output voltage of control voltage compensation arrangement, avoid multiple stage current transformer all to need to draw N line to be connected with the neutral terminal of solar cell serial, thus reducing system cost and line loss, scheme is simple; And be applicable to the photovoltaic generating system of the transformer not possessing neutral terminal.
When containing multiple current transformer in photovoltaic generating system, only this neutral line device and voltage compensating device need be set at the ac output end of a current transformer, can reach all current transformers in elimination system connect the PID impact of photovoltaic group string, thus useful life of all photovoltaic modulies in raising system.
See Fig. 2 a, this figure is photovoltaic generating system embodiment two schematic diagram that the application provides, compared with above-described embodiment one, further, neutral line device 150 comprises three non-polar electric capacity, and one end of described electric capacity links together as the second end of described neutral line device 150; The other end of electric capacity is connected with three of the ac output end of described current transformer respectively.
See Fig. 2 b, this figure is photovoltaic generating system embodiment three schematic diagram that the application provides, compared with above-described embodiment one, further, neutral line device 150 comprises three resistance, and one end of described resistance links together as the second end of described neutral line device 150; The other end of resistance is connected with three of the ac output end of described current transformer respectively.
By utilizing electric capacity or resistance constructing system neutral terminal, scheme is simple, avoids multiple stage current transformer all to need to draw N line and is connected with the neutral terminal of solar cell serial, thus reduce system cost and line loss; And for not possessing the system of transformer of neutral terminal, applicable equally.
Further, refer to Fig. 3, voltage compensating device 140 comprises input unit 1402, voltage transformation module 1404 and output unit 1406;
Described input unit 1402 for from solar cell tandem 110 power taking, or, from primary side 131 or primary side 132 power taking of solar cell serial 130;
Voltage transformation module 1404, sends to output unit 1406 after the voltage for being obtained by described input unit 1402 converts;
Output unit 1406, described output unit 1406 is connected with the second end of described neutral line device 150, for the Voltage Feedback that converted by described voltage transformation module 1404 to the second end of described neutral line device 150 to control the current potential of the second end of neutral line device 150.
Further, described input unit 1402 is specially from the primary side 131 of solar cell serial 130 or primary side 132 power taking: input unit 1402 is from the line voltage of the primary side 131 of solar cell serial 130 or phase voltage power taking; Or input unit 1402 is from the line voltage of the primary side 132 of solar cell serial 130 or phase voltage power taking.
It should be noted that, when input unit is from the primary side of solar cell serial or primary side power taking, alternating current can be converted to galvanic circuit for any type by voltage transformation module 1404.
Refer to Fig. 4 a, this figure is the schematic diagram of the voltage transformation module embodiment that the application provides.
Described voltage transformation module 1404 comprises three-phase main-frequency transformer 1404a, rectifier bridge 1404c, a DC/DC converter 1404b; The primary side of described three-phase main-frequency transformer 1404a connects primary side or the primary side of solar cell serial, rectifier bridge 1404c is connected between the primary side of three-phase main-frequency transformer 1404a and the input of a DC/DC converter 1404b, be used for the AC rectification that the primary side 131 of solar cell serial 130 or primary side 132 obtain to become direct current, the output terminals A of a described DC/DC converter 1404b is connected with the second end of neutral line device 150.
It should be noted that, when input unit is from the power taking of solar cell tandem, voltage transformation module 1404 can be circuit direct current being carried out electric pressure conversion of any type;
Refer to Fig. 4 b, this figure is another schematic diagram of the voltage transformation module embodiment that the application provides.
Described input unit 1402 is from the power taking of described solar cell tandem 110, described voltage transformation module 1404 comprises the 2nd DC/DC converter 1404d, the input of described 2nd DC/DC converter 1404d is connected with PV+ with PV-of described solar cell tandem 110, and the output B of described 2nd DC/DC converter 1404d is connected with the second end of neutral line device 150.
See Fig. 4 c, this figure is the schematic diagram of voltage compensating device way to take power.
Input unit 1402 is from the primary side 131 of solar cell serial 130 or primary side 132 power taking, or, described input unit 1402 is from the power taking of described solar cell tandem 110, can realize by controlling single-pole double-throw switch (SPDT) 1404e, the control signal of described control single-pole double-throw switch (SPDT) 1404e can be sent by current transformer 120, also can be sent by voltage compensating device 140, can also be sent etc. by independently control device, the application does not specifically limit.
It should be noted that, in above-described embodiment, voltage compensating device can, as autonomous device, also can be both a part for any one current transformer had at least one current transformer of direct-flow input end and ac output end, and this current transformer integrally equipment.
The photovoltaic generating system that the application provides, comprises neutral line device and voltage compensating device, and in the first end of described neutral line device and photovoltaic generating system, the ac output end of current transformer and the primary side of solar cell serial are electrically connected; Second end of described voltage compensating device and described neutral line device is electrically connected, and is controlled the current potential of described neutral line device by the output voltage controlling described voltage compensating device, thus solves the problem of the hydraulic performance decline that potential induction attenuation is brought to assembly.When containing multiple current transformer in photovoltaic generating system, only this neutral line device and voltage compensating device need be set at the ac output end of a current transformer, can reach all current transformers in elimination system connect the PID impact of photovoltaic group string, thus useful life of all photovoltaic modulies in raising system.
Present invention also provides the embodiment of voltage compensating device, corresponding to the voltage compensating device in above-mentioned photovoltaic generating system embodiment.
Present invention also provides the embodiment of current transformer in photovoltaic generating system, this current transformer comprises the voltage compensating device in above-described embodiment.
It should be noted that, neutral line device can be a part for any one current transformer had at least one current transformer of direct-flow input end and ac output end, and this current transformer integrally equipment.
Compared with prior art, the voltage compensating device that the application provides and current transformer work simultaneously, the current potential of neutral line device is controlled by the output voltage of control voltage compensation arrangement, avoid multiple stage current transformer all to need to draw N line to be connected with the neutral terminal of solar cell serial, thus reducing system cost and line loss, scheme is simple.
The above is only the preferred embodiment of the application, not does any pro forma restriction to the application.Although the application discloses as above with preferred embodiment, but and be not used to limit the application.Any those of ordinary skill in the art, do not departing under technical scheme ambit, the Method and Technology content of above-mentioned announcement all can be utilized to make many possible variations and modification to technical scheme, or be revised as the Equivalent embodiments of equivalent variations.Therefore, every content not departing from technical scheme, the technical spirit of foundation the application, to any simple modification made for any of the above embodiments, equivalent variations and modification, all still belongs in the scope of technical scheme protection.