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 fossil energy is day by day exhausted and earth environment pollutes, regenerative resource and various green energy resource are obtained and more and more payes attention to and apply, solar power generation is also more and more universal.Along with scale and the application constantly increase of photovoltaic plant, solar module is used in different environments, and various different factors affect the generated output of assembly, causes the decay of component power.PID phenomenon as one of the main cause that numerous initiation component power decays causes to be paid close attention to widely.
PID(PotentialInducedDegradation herein) Chinese is meant to " potential potential induction attenuation ", is the distinctive a kind of phenomenon of photovoltaic battery panel, and this phenomenon is that Sunpower found in 2005 the earliest.Assembly makes to there is leakage current between glass, encapsulating material for a long time under action of high voltage, a large amount of accumulation is on cell piece surface, the passivation effect on cell piece surface is worsened, cause the activity coefficient FF of cell panel, short circuit current Isc, open circuit voltage Voc to reduce, make assembly property lower than design standard.
A large amount of experiments and research show, photovoltaic battery panel is in the while of presenting back bias voltage over the ground under the environment such as high temperature, high humidity, and more easily produce PID phenomenon, and photovoltaic battery panel back bias voltage is larger, PID phenomenon is more serious.The PID phenomenon caused due to back bias voltage is reversible, and photovoltaic battery panel minus earth can eliminate this back bias voltage, effective solution PID problem.But just simply photovoltaic battery panel minus earth can be brought potential safety hazard: if photovoltaic battery panel positive pole is because of fault also ground connection, the short circuit of photovoltaic battery panel both positive and negative polarity will be caused, very likely can cause the major accident 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 just fails.
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 photovoltaic generating system and control method thereof of improvement.
The technical solution adopted for the present invention to solve the technical problems is: provide a kind of photovoltaic generating system, comprise the inverter that photovoltaic battery array and the direct current for being produced by described photovoltaic battery array convert alternating current to, described photovoltaic battery array and described inverter are electrically connected; Described photovoltaic generating system also comprises primary antibodie PID circuit, an insulation resistance detection device 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 is used for fusing when electric current exceedes predetermined value to disconnect described anti-PID circuit; Described insulation resistance detection device is electrically connected with the positive pole of ground and described photovoltaic battery array and negative pole respectively; Described control unit is connected with described insulation resistance detection device and described first switch element;
Detection Information for detecting the second insulation impedance between the positive pole of the first insulation impedance between the negative pole of described photovoltaic battery array and ground and described photovoltaic battery array and ground, and is fed back to described control unit by described insulation resistance detection device; Described control unit generates one first control information according to described Detection Information, and described first control information is sent to described first switch element; Described first switch element to be turned on or off described anti-PID circuit according to described first control information.
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;
This status information feedback for detecting the state information of described fuse, and is given described control unit by described fuse checkout gear; According to described state information, described control unit judges whether described fuse fuses, and it is out of service to control described inverter to described inverter to transmit control signal when described fuse blows.
Preferably, described photovoltaic generating system also comprises 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;
The leakage current information detected is sent to described control unit by described leakage current test unit, and described control unit generates the second control information according to described leakage current information, and described second control information is sent to described first switch element;
Described first switch element to be turned on or off described anti-PID circuit according to described second control information.
Preferably, the leakage current information detected is sent to described control unit by described leakage current test unit, according to described leakage current information, described control unit judges whether described leakage current exceedes predetermined value, and it is out of service to control described inverter to described inverter to transmit control signal when described leakage current exceedes predetermined value.
Preferably, described photovoltaic generating system also comprises 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 generates the 3rd control information according to the state information of described fuse and/or described leakage current information, and described 3rd control information is sent to described second switch unit, described second switch unit is turned on or off according to described 3rd control information.
Preferably, described photovoltaic generating system also comprises 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;
The leakage current information detected is sent to described control unit by described leakage current test unit, and described control unit generates the second control information according to described leakage current information, and described second control information is sent to described first switch element;
Described first switch element to be turned on or off described anti-PID circuit according to described second control information.
Preferably, described control unit is connected with described inverter; The leakage current information detected is sent to described control unit by described leakage current test unit, according to described leakage current information, described control unit judges whether described leakage current exceedes predetermined value, and it is out of service to control described inverter to described inverter to transmit control signal when described leakage current exceedes predetermined value.
Present invention also offers a kind of control method of photovoltaic generating system, comprise the following steps:
S1: described insulation resistance detection device 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 generates one first control information according to described Detection Information, and described first control information is sent to described first switch element;
S3: described first switch element to be turned on or off described anti-PID circuit according to described first control information.
Preferably, be connected by described control unit with described inverter, described control method also comprises:
S4: the state information detecting 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 controls the operation or out of service of described inverter according to described control signal.
Implement photovoltaic generating system of the present invention, there is following beneficial effect: photovoltaic generating system provided by the invention is on the one hand by being provided with insulation resistance detection device to detect the first insulation impedance between the positive and negative electrode of photovoltaic battery array and ground and the second insulation impedance respectively, before whole photovoltaic generating system runs prerequisite, detect fault, can be avoided the state of insulation that cannot judge negative pole cable or cell panel negative pole end because of minus earth and cause the problem that fail safe cannot be determined; Achieve cell panel minus earth on the other hand, successfully eliminate PID phenomenon.
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
In order to there be understanding clearly to technical characteristic of the present invention, object and effect, 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 resistance detection device 4 and control unit 5.The positive and negative electrode of photovoltaic battery array 1 corresponds respectively to the positive and negative electrode electric connection of the direct-flow input end of inverter 2.
Inverter 2 goes for direct current being converted to alternating current and being input in electrical network after boosting.
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, be connected on after fuse 31 and the first switch element 32 are connected in series and the negative pole of photovoltaic battery array 1 between.First switch element 32 is for controlling the break-make of anti-PID circuit 3.Fuse 31 for pass through at the positive pole of photovoltaic battery array 1 negative pole short circuit with photovoltaic battery array 1 time fuse to disconnect anti-PID circuit 3.
Insulation resistance detection device 4 is electrically connected with the positive and negative electrode of photovoltaic battery array 1 and ground respectively.Detection Information for detecting the second insulation impedance R-between the negative pole of the first insulation impedance R+ between the positive pole of photovoltaic battery array 1 and ground and photovoltaic battery array 1 and ground, and is fed back to control unit 5 by insulation resistance detection device 4.In the present embodiment, insulation resistance detection device 4 is the common apparatus of prior art, and therefore not to repeat here.
Control unit 5 is electrically connected with the first switch element 32 of insulation resistance detection device 4 and anti-PID circuit 3.Control unit 5 generates the first control information according to the Detection Information of insulation resistance detection device 4, and the first control information is sent to the first switch element 32; First switch element 32 to be turned on or off anti-PID circuit 3 according to the first control information.Particularly, control unit 5, when R+ and R-is all greater than a certain preset value, makes the conducting of anti-PID circuit 3 by closed for the first switch element 32, and then photovoltaic generating system can bring into operation work.In the present embodiment, this preset value is U/30mA, and wherein U is the maximum voltage between the positive and negative electrode of photovoltaic battery array 1.
Photovoltaic generating system that the present embodiment provides is on the one hand by being provided with insulation resistance detection device to detect the first insulation impedance between the positive and negative electrode of photovoltaic battery array and ground and the second insulation impedance respectively, before whole photovoltaic generating system runs prerequisite, detect fault, can be avoided the state of insulation that cannot judge negative pole cable or cell panel negative pole end because of minus earth and cause the problem that fail safe cannot be determined; Achieve cell panel minus earth on the other hand, successfully eliminate PID phenomenon.As negative pole cable fault earthing, the short-circuit loop of positive pole changes, and short circuit current can not flow through the fuse 31 in anti-PID circuit 3, cannot play fuse protection effect.It can also detect positive pole whether misconnection before whole photovoltaic generating system runs, and can prevent the both positive and negative polarity of photovoltaic battery array 1 in some cases from passing through ground short circuit.
Fig. 2 shows the photovoltaic generating system in another embodiment of the present invention, and it adds 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 detecting 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 the leakage current information detected is sent to control unit 5 by leakage current test unit 6.According to leakage current information, control unit 5 judges whether leakage current exceedes predetermined value, and it is out of service to control inverter 2 to inverter 2 to transmit control signal when leakage current exceedes predetermined value; Or generate control information according to leakage current information, and the first switch element 32, first switch element 32 control information is sent to be turned on or off PID circuit 3 according to control information; Or generate control information according to leakage current information, and control information is sent to second switch unit 7, second switch unit 7 is turned on or off according to control information the connection of inverter 2 and photovoltaic battery array 1.By arranging leak current detection device, achieving the Real-Time Monitoring to photovoltaic generating system leakage current, protecting the personal safety that may get an electric shock, it also avoid the device damage that contact short circuit may cause.
In the present embodiment, fuse 32 is also 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, the connection of inverter 2 and electrical network can be disconnected, and second switch unit 7 can disconnect inverter 2 and the connection of photovoltaic battery array 1, guarantees maintenance safe.Achieve 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 the leakage current information that detects of leakage current test unit 6 generate the 3rd control information, and the 3rd control information is sent to second switch unit 7, second switch unit 7 is turned on or off according to the 3rd control information.Inverter 2 and photovoltaic battery array 1 cut off when leakage current exceedes preset value or when fuse 31 fuses by second switch unit 7.Second switch unit 7 when leakage current does not exceed preset value and fuse 31 does not fuse time by inverter 2 and photovoltaic battery array 1 conducting.It adopts conventional switching circuit to realize.
In above two embodiments, anti-PID circuit 3, insulation resistance detection device 4, leakage current test unit 6 and fuse checkout gear are all arranged in inverter 4 or intelligent DC power distribution cabinet or intelligent junction box.And control unit 5 is independently control chip or be integrated in the intelligent control unit 5 of inverter 2 or intelligent DC power distribution cabinet or intelligent junction box.
Present invention also offers a kind of control method of photovoltaic generating system, 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 resistance detection device 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 generates one first control information according to Detection Information, and the first control information is sent to the first switch element 32;
Step S3: the first switch element 32 to be turned on or off anti-PID circuit 3 according to the first control information.
In other embodiments, be connected by control unit 5 with inverter 2, this control method also comprises:
S4: 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, inverter 2 controls inverter 2 according to control signal and to run or out of service.When fuse 31 fuse and leakage current exceed in predetermined value two events have the generation of event time, inverter 2 is out of service.When these two events all do not occur, inverter 2 runs.
By reference to the accompanying drawings embodiments of the invention are described above; but the present invention is not limited to above-mentioned embodiment; above-mentioned embodiment is only schematic; instead of it is restrictive; those of ordinary skill in the art is under enlightenment of the present invention; do not departing under the ambit that present inventive concept and claim protect, also can make a lot of form, these all belong within protection of the present invention.