A kind of photovoltaic generating system and control method thereof
Technical field
The present invention relates to field of photovoltaic power generation, be specifically related to a kind of photovoltaic generating system and control method thereof.
Background technology
Constantly serious along with what fossil energy was day by day exhausted and earth environment pollutes, make regenerative resource and various green energy resource obtain increasing attention and application, solar power generation is also more and more universal.Along with scale and the constantly increase of application of photovoltaic plant, solar module is used in varying environment, and various factor affects the generated output of assembly, causes the decay of component power.The PID phenomenon of one of main cause decayed as numerous initiation component power has caused widely to be paid close attention to.
PID(Potential Induced Degradation herein) the Chinese meaning is " potential electromotive force is induced decay ", is the distinctive a kind of phenomenon of photovoltaic battery panel, and this phenomenon is that Sunpower found in 2005 the earliest.Assembly makes between glass, encapsulating material and has leakage current for a long time under action of high voltage, a large amount of accumulation are on the cell piece surface, make the passivation effect on cell piece surface worsen, cause activity coefficient FF, short circuit current Isc, the open circuit voltage Voc of cell panel to reduce, make assembly property lower than design standard.
A large amount of experiment and researchs show, photovoltaic battery panel, in presenting over the ground back bias voltage simultaneously under the environment such as high temperature, high humidity, more easily produce the PID phenomenon, and the photovoltaic battery panel back bias voltage is larger, and the PID phenomenon is more serious.The PID phenomenon caused due to back bias voltage is reversible, and the photovoltaic battery panel minus earth can be eliminated this back bias voltage, effectively solves the PID problem.But just simply the photovoltaic battery panel minus earth can be brought to potential safety hazard: if the photovoltaic battery panel positive pole hinders also ground connection for some reason, will cause the short circuit of photovoltaic battery panel both positive and negative polarity, very likely can cause the major accidents such as equipment burnout, fire.If the negative pole of photovoltaic battery panel is with other path grounds beyond anti-PID circuit, the fuse in so anti-PID circuit had just lost efficacy.
Summary of the invention
The technical problem to be solved in the present invention is, for the defect existed in prior art, provides a kind of improved photovoltaic generating system and control method thereof.
The technical solution adopted for the present invention to solve the technical problems is: a kind of photovoltaic generating system is provided, comprise photovoltaic battery array and convert the inverter of alternating current to for the direct current that described photovoltaic battery array is produced, described photovoltaic battery array and the electric connection of described inverter; Described photovoltaic generating system also comprises primary antibodie PID circuit, an insulation impedance checkout gear and a control unit;
One end of described anti-PID circuit is electrically connected at the negative pole of described photovoltaic battery array, other end ground connection; Described anti-PID circuit comprises fuse and first switch element of series connection, and described fuse for fusing to disconnect described anti-PID circuit when electric current surpasses predetermined value; Described insulation impedance checkout gear is electrically connected with positive pole and the negative pole of ground and described photovoltaic battery array respectively; Described control unit is connected with described insulation impedance checkout gear and described the first switch element;
Described insulation impedance checkout gear is for detection of negative pole and the positive pole of the first insulation impedance between ground and described photovoltaic battery array and second insulation impedance between ground of described photovoltaic battery array, and detection information is fed back to described control unit; Described control unit is according to described detection Information generation one first control information, and described the first control information is sent to described the first switch element; Described the first switch element is according to described the first control information conducting or disconnect described anti-PID circuit.
Preferably, described control unit is connected with described inverter, and described photovoltaic generating system also comprises a fuse checkout gear, and described fuse checkout gear is connected with described control unit;
Described fuse checkout gear is for detection of the state information of described fuse, and gives described control unit by this status information feedback; Described control unit judges according to described state information whether described fuse fuses, and it is out of service to control described inverter to described inverter when described fuse blows, to transmit control signal.
Preferably, described photovoltaic generating system also comprises the leakage current test unit, and described leakage current test unit is electrically connected between described anti-PID circuit and ground, and is connected with described control unit;
Described leakage current test unit sends to described control unit by the leakage current information detected, and described control unit is according to described leakage current Information generation the second control information, and described the second control information is sent to described the first switch element;
Described the first switch element is according to described the second control information conducting or disconnect described anti-PID circuit.
Preferably, described leakage current test unit sends to described control unit by the leakage current information detected, described control unit judges according to described leakage current information whether described leakage current surpasses predetermined value, and it is out of service to control described inverter to described inverter when described leakage current surpasses predetermined value, to transmit control signal.
Preferably, described photovoltaic generating system also comprises the second switch unit, and described second switch list closes and is electrically connected between described photovoltaic battery array and described inverter;
Described control unit is connected with described second switch unit, described control unit is according to state information and/or the 3rd control information of described leakage current Information generation of described fuse, and described the 3rd control information is sent to described second switch unit, described second switch unit is according to described the 3rd control information conducting or disconnection.
Preferably, described photovoltaic generating system also comprises the leakage current test unit, and described leakage current test unit is electrically connected between described anti-PID circuit and ground, and is connected with described control unit;
Described leakage current test unit sends to described control unit by the leakage current information detected, and described control unit is according to described leakage current Information generation the second control information, and described the second control information is sent to described the first switch element;
Described the first switch element is according to described the second control information conducting or disconnect described anti-PID circuit.
Preferably, described control unit is connected with described inverter; Described leakage current test unit sends to described control unit by the leakage current information detected, described control unit judges according to described leakage current information whether described leakage current surpasses predetermined value, and it is out of service to control described inverter to described inverter when described leakage current surpasses predetermined value, to transmit control signal.
The present invention also provides a kind of control method of photovoltaic generating system, comprises the following steps:
S1: described insulation impedance checkout gear detects the positive pole of described photovoltaic battery array and the insulation impedance between negative pole and ground, and detection information is fed back to described control unit;
S2: described control unit is according to described detection Information generation one first control information, and described the first control information is sent to described the first switch element;
S3: described the first switch element is according to described the first control information conducting or disconnect described anti-PID circuit.
Preferably, described control unit is connected with described inverter, described control method also comprises:
S4: detect the state information of described fuse, and described state information is sent to described control unit; Detect the leakage current information of described photovoltaic battery array, and described leakage current information is sent to described control unit;
S5: described control unit produces a control signal according to described state information and/or described leakage current information, and described control signal is sent to described inverter, described inverter is controlled described inverter operation or out of service according to described control signal.
Implement photovoltaic generating system of the present invention, have following beneficial effect: photovoltaic generating system provided by the invention is on the one hand by being provided with positive and negative electrode and first insulation impedance ground between and second insulation impedance of insulation impedance checkout gear to detect respectively photovoltaic battery array, detect fault before whole photovoltaic generating system operation prerequisite, can avoid causing because minus earth can't judge the state of insulation of negative pole cable or cell panel negative pole end the problem that fail safe can't be definite; Realized on the other hand the cell panel minus earth, successful elimination PID phenomenon.
The accompanying drawing explanation
Below in conjunction with drawings and Examples, the invention will be further described, in accompanying drawing:
Fig. 1 illustrates the structured flowchart of the photovoltaic generating system in one embodiment of the invention;
Fig. 2 shows the structured flowchart of the photovoltaic generating system in another embodiment of the present invention.
Embodiment
Understand for technical characterictic of the present invention, purpose and effect being had more clearly, now contrast accompanying drawing and describe the specific embodiment of the present invention in detail.
Fig. 1 shows the photovoltaic generating system in one embodiment of the invention, comprises photovoltaic battery array 1, inverter 2, anti-PID circuit 3, insulation impedance checkout gear 4 and control unit 5.The positive and negative electrode that the positive and negative electrode of photovoltaic battery array 1 corresponds respectively to the direct-flow input end of inverter 2 is electrically connected.
Inverter 2 for direct current is converted to alternating current and boost after be input to electrical network.
Anti-PID circuit 3 be electrically connected at and the negative pole of photovoltaic battery array 1 between.Anti-PID circuit 3 comprises the first switch element 32 and fuse 31, after fuse 31 and the first switch element 32 are connected in series, be connected on and the negative pole of photovoltaic battery array 1 between.The first switch element 32 is for controlling the break-make of anti-PID circuit 3.Fuse 31 fuses to disconnect anti-PID circuit 3 during the negative pole short circuit by ground and photovoltaic battery array 1 for the positive pole at photovoltaic battery array 1.
Insulation impedance checkout gear 4 is electrically connected with positive and negative electrode and the ground of photovoltaic battery array 1 respectively.Insulation impedance checkout gear 4 is for detection of positive pole and the negative pole of the first insulation impedance R+ between ground and photovoltaic battery array 1 and the second insulation impedance R-between ground of photovoltaic battery array 1, and detection information is fed back to control unit 5.In the present embodiment, the common apparatus that insulation impedance checkout gear 4 is prior art, therefore not to repeat here.
Control unit 5 is electrically connected with the first switch element 32 of insulation impedance checkout gear 4 and anti-PID circuit 3.Control unit 5 is according to detection Information generation first control information of insulation impedance checkout gear 4, and the first control information is sent to the first switch element 32; The first switch element 32 is according to the first control information conducting or disconnect anti-PID circuit 3.Particularly, control unit 5, when R+ and R-all are greater than a certain preset value, makes anti-PID circuit 3 conductings by the first switch element 32 closures, and then the photovoltaic generating system work that can bring into operation.In the present embodiment, this preset value is U/30mA, the maximum voltage between the positive and negative electrode that wherein U is photovoltaic battery array 1.
The photovoltaic generating system that the present embodiment provides is on the one hand by being provided with positive and negative electrode and first insulation impedance ground between and second insulation impedance of insulation impedance checkout gear to detect respectively photovoltaic battery array, detect fault before whole photovoltaic generating system operation prerequisite, can avoid causing because minus earth can't judge the state of insulation of negative pole cable or cell panel negative pole end the problem that fail safe can't be definite; Realized on the other hand the cell panel minus earth, successful elimination PID phenomenon.As negative pole cable fault earthing, anodal short-circuit loop changes, and the short circuit current fuse 31 in anti-PID circuit 3 of can not flowing through, can't play the fuse protection effect.It can also before the operation of whole photovoltaic generating system, detect positive pole whether misconnection, can prevent that the both positive and negative polarity of the photovoltaic battery array 1 in some situation from passing through ground short circuit.
Fig. 2 shows the photovoltaic generating system in another embodiment of the present invention, and it has increased leakage current test unit 6, second switch unit 7 and fuse checkout gear (not shown) on the basis of a upper embodiment.Leakage current test unit 6 is electrically connected between anti-PID circuit 3 and ground.Second switch unit 7 is electrically connected between photovoltaic battery array 1 and inverter 2.Wherein inverter 2, leakage current test unit 6, second switch unit 7 are electrically connected with control unit 5 respectively.
Leakage current test unit 6 is for detection of the negative pole leakage current of photovoltaic battery array 1, and it can be the higher ammeter of sensitivity or other current sensing means, and leakage current test unit 6 sends to control unit 5 by the leakage current information detected.Control unit 5 judges according to leakage current information whether leakage current surpasses predetermined value, and it is out of service to control inverter 2 to inverter 2 when leakage current surpasses predetermined value, to transmit control signal; Or according to the control information of leakage current Information generation, and control information is sent to the first switch element 32, the first switch elements 32 according to the control information conducting or disconnects PID circuit 3; Or, according to the control information of leakage current Information generation, and control information being sent to second switch unit 7, second switch unit 7 is according to the control information conducting or disconnect being connected of inverter 2 and photovoltaic battery array 1.By leak current detection device is set, realized the Real-Time Monitoring to the photovoltaic generating system leakage current, protected the personal safety that may get an electric shock, the device damage of also having avoided the contact short circuit to cause.
In the present embodiment, fuse 32 also is provided with a fuse checkout gear (not shown), to detect the state information of fuse, and by this status information feedback to control unit 5.This fuse checkout gear and control unit 5 are electrically connected.When fuse blows, it is out of service that control unit 5 sends control signal control inverter 2.Further, can disconnect being connected of inverter 2 and electrical network, and second switch unit 7 can disconnect being connected of inverter 2 and photovoltaic battery array 1, guarantee maintenance safe.Realized like this remote monitoring of fuse 31 and be convenient to the maintenance of this photovoltaic generating system.
Second switch unit 7 is for controlling the break-make between inverter 2 and photovoltaic battery array 1.Control unit 5 according to the state information of fuse 31 and or leakage current Information generation the 3rd control information that detects of leakage current test unit 6, and the 3rd control information is sent to second switch unit 7, second switch unit 7 is according to the 3rd control information conducting or disconnection.Second switch unit 7 when leakage current surpasses preset value or during fuse 31 fusing cuts off inverter 2 and photovoltaic battery array 1.Second switch unit 7 when leakage current does not surpass preset value and fuse 31 while not fusing by inverter 2 and photovoltaic battery array 1 conducting.It adopts switching circuit commonly used to realize.
In above two embodiment, anti-PID circuit 3, insulation impedance checkout gear 4, leakage current test unit 6 and fuse checkout gear all are arranged in inverter 4 or intelligent DC power distribution cabinet or intelligent junction box.And control unit 5 for control chip independently or be integrated in inverter 2 or the intelligent control unit 5 of intelligent DC power distribution cabinet or intelligent junction box in.
The present invention also provides a kind of control method of photovoltaic generating system, and photovoltaic generating system is set forth in the above-described embodiments, and therefore not to repeat here, and control method comprises the following steps:
Step S1: insulation impedance checkout gear 4 detects the positive pole of photovoltaic battery array 1 and the insulation impedance between negative pole and ground, and detection information is fed back to control unit 5;
Step S2: control unit 5 is according to detecting Information generation one first control information, and the first control information is sent to the first switch element 32;
Step S3: the first switch element 32 is according to the first control information conducting or disconnect anti-PID circuit 3.
In other embodiments, control unit 5 is connected with inverter 2, this control method also comprises:
S4: the fuse checkout gear detects the state information of fuse 31, and state information is sent to control unit 5; Detect the leakage current information of photovoltaic battery array 1, and leakage current information is sent to control unit 5;
S5: control unit 5 produces a control signal according to state information and/or leakage current information, and control signal is sent to inverter 2, and inverter 2 is controlled inverter 2 operations or out of service according to control signal.When fuse 31 fusing and leakage current surpass in two events of predetermined value when an event generation is arranged, inverter 2 is out of service.Inverter 2 operations when these two events all do not occur.
The above is described embodiments of the invention by reference to the accompanying drawings; but the present invention is not limited to above-mentioned embodiment; above-mentioned embodiment is only schematic; rather than restrictive; those of ordinary skill in the art is under enlightenment of the present invention; not breaking away from the scope situation that aim of the present invention and claim protect, also can make a lot of forms, within these all belong to protection of the present invention.