CN103475030B - A kind of Countercurrent prevention control method and device - Google Patents
A kind of Countercurrent prevention control method and device Download PDFInfo
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- CN103475030B CN103475030B CN201310450441.7A CN201310450441A CN103475030B CN 103475030 B CN103475030 B CN 103475030B CN 201310450441 A CN201310450441 A CN 201310450441A CN 103475030 B CN103475030 B CN 103475030B
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/50—Photovoltaic [PV] energy
- Y02E10/56—Power conversion systems, e.g. maximum power point trackers
Abstract
The invention provides a kind of Countercurrent prevention control method and device, whether described method comprises: with some cycles cycle detection photovoltaic generating system to the reverse power transmission of public electric wire net, if, then send the first control signal to described photovoltaic generating system, if not, then the second control signal is sent to described photovoltaic generating system; First control signal controls described photovoltaic generating system downrating, and the second control signal controls described photovoltaic generating system power per liter and runs.Visible, the present invention is no longer the connection cutting off photovoltaic generating system and public electric wire net, also the switch of photovoltaic generating system is no longer disconnected, but whether have reverse power transmission by cycle detection, the power of real-time rising or reduction photovoltaic generating system, the real-time matching of electric energy needed for the electric energy that photovoltaic generating system is sent and load circuit, make use of the generating electric energy of photovoltaic generating system fully, decreases the waste of the generating electric energy of photovoltaic generating system while preventing reverse power transmission from occurring.
Description
Technical field
The present invention relates to power grid control field, especially relate to a kind of Countercurrent prevention control method and device.
Background technology
Grid-connected photovoltaic system comprises photovoltaic generating system, public electric wire net and load circuit, wherein by photovoltaic generating system with public electric wire net parallel connection is common afterwards powers to load circuit.When the electric energy that photovoltaic generating system exports is less than the electricity consumption of load circuit, by public electric wire net to load circuit supplementary power, and when the electric energy that photovoltaic generating system exports is greater than the electricity consumption of load circuit, unnecessary electric energy to the reverse power transmission of public electric wire net, namely may cause adverse current.Due to photovoltaic generating system export unnecessary electric energy be incorporated to public electric wire net after can cause public electric wire net instability and produce harmonic pollution, there is non-scheduling in photovoltaic electric energy simultaneously, therefore, the electric energy that photovoltaic generating system be prevented unnecessary is to the reverse power transmission of public electric wire net.
In prior art, when preventing photovoltaic generating system power transmission reverse to public electric wire net, the way of usual employing is that following power has a grade regulative mode: when the electric energy that photovoltaic generating system exports be greater than load circuit use electric energy time, cut off the connection between photovoltaic generating system and public electric wire net immediately, or the switch of breaking part photovoltaic generating system.If cut off the connection between photovoltaic generating system and public electric wire net immediately, then now all powered to load circuit by public electric wire net, if the switch of breaking part photovoltaic generating system, because a usual capacity of switch of photovoltaic generating system is larger, even if the therefore switch of only breaking part photovoltaic generating system, public electric wire net also probably can be caused to need to power to load circuit relatively high power.Therefore, these two kinds of power have grade regulative mode situation all to cause the waste of the generating electric energy of photovoltaic generating system.
Summary of the invention
The technical problem that the present invention solves is to provide a kind of Countercurrent prevention control method and device, realize the waste of the generating electric energy reducing photovoltaic generating system while preventing the reverse power transmission of photovoltaic generating system, thus the generating electric energy of photovoltaic generating system can be made full use of.
For this reason, the technical scheme of technical solution problem of the present invention is:
The invention provides a kind of Countercurrent prevention control method, described method comprises:
With some cycles cycle detection photovoltaic generating system whether to the reverse power transmission of public electric wire net, if so, then send the first control signal to described photovoltaic generating system, if not, then send the second control signal to described photovoltaic generating system;
Described first control signal controls described photovoltaic generating system downrating, and described second control signal controls described photovoltaic generating system power per liter and runs;
Described photovoltaic generating system backward load circuit in parallel with described public electric wire net is powered.
Preferably, when whether described detection photovoltaic generating system is no to the testing result of the reverse power transmission of public electric wire net, described method also comprises: judge on photovoltaic generating system, whether a cycle is downrating, if, then send the 3rd control signal to described photovoltaic generating system, if not, then perform and describedly send the second control signal to described photovoltaic generating system;
Described 3rd control signal controls described photovoltaic generating system and keeps current power to run.
Preferably, described method also comprises:
When sending the first control signal to described photovoltaic generating system, arranging counterflow-preventing flag bit is first; When sending the 3rd control signal to described photovoltaic generating system, arranging counterflow-preventing flag bit is second;
Then describedly judge on photovoltaic generating system, whether a cycle is that downrating is specially: judge that counterflow-preventing flag bit is first or second, if be first, then describedly judge that cycle on photovoltaic generating system be whether the judged result of downrating is yes, if be second, then describedly judge that cycle on photovoltaic generating system be whether the judged result of downrating is no.
Preferably, described method also comprises: when arranging counterflow-preventing flag bit and being first, set timer is initial value and starts timing;
Described setting before counterflow-preventing flag bit is second also comprises:
Judge whether described timer timing reaches Preset Time, if so, then performing the described counterflow-preventing flag bit that arranges is second.
Preferably, during whether reverse to the public electric wire net power transmission of described detection photovoltaic generating system, also comprise: detect the electric energy size flowing to or flow out public electric wire net;
Described first control signal controls the speed of described photovoltaic generating system downrating according to the electric energy size detected, described second control signal controls the speed of described photovoltaic generating system power per liter operation according to the electric energy size detected.
Preferably, whether described detection photovoltaic generating system is specially to the reverse power transmission of public electric wire net: whether detect photovoltaic generating system to the reverse power transmission of public electric wire net by instrument transformer, electric energy meter or bidirectional measuring table.
The invention provides a kind of counterflow-preventing control device, described device comprises: adverse current detecting unit and adverse current control unit;
Described adverse current control unit be used for by described adverse current detecting unit with some cycles cycle detection photovoltaic generating system whether to the reverse power transmission of public electric wire net, if, then send the first control signal to described photovoltaic generating system, if not, then the second control signal is sent to described photovoltaic generating system;
Described first control signal controls described photovoltaic generating system downrating, and described second control signal controls described photovoltaic generating system power per liter and runs;
Described photovoltaic generating system backward load circuit in parallel with described public electric wire net is powered.
Preferably, described adverse current control unit also for, when whether described adverse current detecting unit to detect photovoltaic generating system be no to the testing result of the reverse power transmission of public electric wire net, judge on photovoltaic generating system, whether a cycle is downrating, if, then send the 3rd control signal to described photovoltaic generating system, if not, then perform and describedly send the second control signal to described photovoltaic generating system;
Described 3rd control signal controls described photovoltaic generating system and keeps current power to run.
Preferably, described adverse current detecting unit is instrument transformer, electric energy meter or bidirectional measuring table.
Preferably, described photovoltaic generating system comprises at least one photovoltaic DC-to-AC converter.
Known by technique scheme, in the present invention with some cycles cycle detection photovoltaic generating system whether to the reverse power transmission of public electric wire net, if testing result is yes, sends the first control signal to photovoltaic generating system and make photovoltaic generating system downrating, thus prevent reverse power transmission; If testing result is no, sends the second control signal to photovoltaic generating system and photovoltaic generating system power per liter is run.Visible, the present invention is no longer the connection cutting off photovoltaic generating system and public electric wire net, also the switch of photovoltaic generating system is no longer disconnected, but whether have reverse power transmission by cycle detection, the power of real-time rising or reduction photovoltaic generating system, thus achieve a kind of stepless regulative mode, the real-time matching of electric energy needed for the electric energy that photovoltaic generating system is sent and load circuit.And this stepless regulative mode, make the generating electric energy that make use of photovoltaic generating system while preventing reverse power transmission from occurring fully, decrease the waste of the generating electric energy of photovoltaic generating system.
Accompanying drawing explanation
Fig. 1 is the schematic flow sheet of the first embodiment of Countercurrent prevention control method provided by the invention;
Fig. 2 is the schematic flow sheet of the second embodiment of Countercurrent prevention control method provided by the invention;
Fig. 3 is the structural representation of the specific embodiment of counterflow-preventing control device provided by the invention.
Embodiment
In prior art, when preventing photovoltaic generating system power transmission reverse to public electric wire net, the way of usual employing is at public electric wire net, installs a kind of special counterflow-preventing equipment between load circuit and photovoltaic generating system additional, and this equipment comprises inverse probability collector, reverse power controller and switching circuit.Inverse probability collector detects public electric wire net side and load circuit information and by the information transmission that detects to reverse power controller, according to the information that inverse probability collector detects, reverse power controller has judged that electric energy is to the reverse power transmission of public electric wire net, that is when the electric energy exported when photovoltaic generating system is greater than the electricity consumption of load circuit, by the connection between control switch circuitry cuts photovoltaic generating system and public electric wire net, or the switch of cut-off parts photovoltaic generating system.
Obviously, in prior art be a kind of regulative mode having level.If cut off the connection between photovoltaic generating system and public electric wire net immediately, then now all powered to load circuit by public electric wire net, the output electric energy of photovoltaic generating system has just all been wasted; If the switch of breaking part photovoltaic generating system, because a switch of photovoltaic generating system controls larger power usually, even if therefore only disconnect the switch of a photovoltaic generating system, public electric wire net needs also probably can be caused to load circuit to power more.Such as, photovoltaic generating system can export the electric energy of 200kw power, if the power now needed for load is 198kw, now there will be reverse power transmission, therefore, need the switch cutting off photovoltaic generating system, if photovoltaic generating system has four switches, when cut-out switch, then photovoltaic generating system can only export the electric energy of 150kw power, and the residue 48kw power needed for load then needs to be provided by public electric wire net.Obviously, this mode also result in the waste of the generating electric energy of photovoltaic generating system.
Further, this mode of prior art also needs to install switching circuit, and needs the special reverse power controller of exploitation to be used for control switch circuit, and cost is higher, realizes also comparatively complicated.
And in embodiments of the present invention, provide a kind of Countercurrent prevention control method and device, realize the waste of the generating electric energy reducing photovoltaic generating system while preventing the reverse power transmission of photovoltaic generating system, thus the generating electric energy of photovoltaic generating system can be made full use of.
For enabling above-mentioned purpose of the present invention, feature and advantage become apparent more, are described in detail the embodiment of the present invention below in conjunction with accompanying drawing.
Refer to Fig. 1, the invention provides the first embodiment of Countercurrent prevention control method, in the present embodiment, after in parallel with public electric wire net by photovoltaic generating system, jointly power to load circuit.
Described in the present embodiment, method comprises:
S101 is performed with some cycles circulation.
S101: whether detect photovoltaic generating system to the reverse power transmission of public electric wire net, if, then illustrate this detect in be tested with photovoltaic generating system to the reverse power transmission of public electric wire net, now perform S102, if not, then illustrate in this detects, do not detect that photovoltaic generating system is to the reverse power transmission of public electric wire net, now performs S103.
Detect in step S101 and whether have reverse power transmission, the flow of electrical power direction specifically can detecting the low-pressure grid-connection point of public electric wire net has judged whether reverse power transmission.And can be that the information detected by adverse current detecting units such as instrument transformer, electric energy meter or bidirectional measuring tables by adverse current control unit has judged whether reverse power transmission,
S102: send the first control signal to described photovoltaic generating system.Described first control signal controls described photovoltaic generating system downrating.
Now be tested with reverse power transmission, therefore send the first control signal to photovoltaic generating system and make photovoltaic generating system downrating, thus prevent reverse power transmission.
The electric energy size detecting and flow to or flow out public electric wire net can also be performed while performing step S101, then described first control signal can also control the speed of described photovoltaic generating system downrating according to the electric energy size detected, such as, described first control signal can by regulating the parameter of falling power slope curve, such as the first Preset Time constant τ 1 adjusts the slope falling power curve, thus Power Ratio falls in adjustment.
In actual motion, grid company has put into effect the requirement preventing reverse power transmission of photovoltaic plant access electrical network: when design of photovoltaic power station is irreversible synchronizing mode, when detecting that backward current exceedes 5% of specified output, photovoltaic plant should stop to power network line power transmission in 0.5 ~ 2 S.In the present embodiment, by arranging the parameter (such as the first preset constant τ 1) of falling power slope curve, reverse power transmission requirement can be prevented to meet the above-mentioned of grid company.Can be specifically the electric energy size of the reverse power transmission detected according to adverse current detecting unit by adverse current control unit, send first control signal with the parameter of falling power slope curve to photovoltaic generating system, to meet the requirement preventing reverse power transmission.It should be noted that, the circulation in the present embodiment performs the cycle of S101, also can set according to the above-mentioned requirements of grid company.Under normal circumstances, need to arrange shorter cycle, to keep the electric energy needed for the generating electric energy of coupling photovoltaic generating system that can be real-time and load circuit, and whether Timeliness coverage has reverse power transmission.Such as, can arrange this cycle is 1ms.
S103: send the second control signal to described photovoltaic generating system.Described second control signal controls described photovoltaic generating system power per liter and runs.
Now, do not detect reverse power transmission, therefore send the second control signal to photovoltaic generating system and photovoltaic generating system power per liter is run.The electric energy size detecting and flow to or flow out public electric wire net can also be performed while performing step S101, described second control signal can also control the speed that described photovoltaic generating system power per liter is run according to the electric energy size detected, such as, described second control signal can also be provided with the parameter of power per liter slope curve, such as the second Preset Time constant τ 2.Therefore, the parameter of the size adjustment power per liter slope curve of electric energy can be exported according to public electric wire net, thus the speed of adjustment power per liter.
In the present embodiment, after performing S101 in each cycle, the testing result according to S101 performs S102 or S103, after executing S102 or S102, returns perform S101 when next cycle starts, thus ensures that circulation performs S101.During specific implementation, can be that adverse current control unit calls counterflow-preventing program within the cycle of each circulation, often call once described counterflow-preventing program, the information and executing S101 that will be detected by adverse current detecting unit.
In the present embodiment, if when the generating electric energy of certain moment photovoltaic generating system is less than electric energy needed for load circuit, this moment, power per liter was run by photovoltaic generating system without the need to counterflow-preventing, to utilize photovoltaic electric energy fully; If electric energy needed for certain moment load circuit reduces, when the generating electric energy of photovoltaic generating system is greater than electric energy needed for load circuit, there is reverse power transmission in this moment, downrating in case non-return to power transmission, thus is reached the supply and demand coupling of electric energy needed for the generating electric energy of photovoltaic generating system and load circuit by photovoltaic generating system.And electric energy changes in the moment needed for load circuit, and variation tendency is also difficult to prediction, therefore, need real-time detection whether to have reverse power transmission in the present embodiment, electric energy needed for the generating electric energy of guarantee real-time matching photovoltaic generating system and load circuit.
Known by technique scheme, in the present embodiment with some cycles cycle detection photovoltaic generating system whether to the reverse power transmission of public electric wire net, if testing result is yes, sends the first control signal to photovoltaic generating system and make photovoltaic generating system downrating, thus prevent reverse power transmission; If testing result is no, sends the second control signal to photovoltaic generating system and photovoltaic generating system power per liter is run, thus make full use of photovoltaic generation electric energy.Visible, the present invention is no longer the connection cutting off photovoltaic generating system and public electric wire net, also the switch of photovoltaic generating system is no longer disconnected, but whether have reverse power transmission by cycle detection, the power of real-time rising or reduction photovoltaic generating system, thus achieve a kind of regulative mode without progression, the real-time matching of electric energy needed for the electric energy that photovoltaic generating system is sent and load circuit.And this regulative mode without progression, make the generating electric energy that make use of photovoltaic generating system while preventing reverse power transmission from occurring fully, decrease the waste of the generating electric energy of photovoltaic generating system.
Such as, photovoltaic generating system can export the electric energy of 200kw power, if the power now needed for load is 198kw, now there will be reverse power transmission.If adopt the mode of prior art, cut off photovoltaic generating system and the connection of public electric wire net or the switch of breaking part photovoltaic generating system, all can cause the waste of the generating electric energy of photovoltaic generating system.Such as, if cut off the connection of photovoltaic generating system and public electric wire net, the electric energy that then photovoltaic generating system sends all is wasted, public electric wire net needs the electric energy exporting 198kw power, if the switch of breaking part photovoltaic generating system, if photovoltaic generating system has four switches, when cut-out switch, then photovoltaic generating system can only export the electric energy of 150kw power, now also result in the waste of the electric energy that part photovoltaic generating system sends, public electric wire net needs the electric energy exporting 48kw power.And if adopt mode of the present invention, photovoltaic generating system can be operated in by output first control signal and fall power, photovoltaic generating system can be made to export the power of 198kw or 197kw, and now public electric wire net need export 1kw or not need to export electric energy completely.Obviously, this mode of the present invention, can reduce the waste of the generating electric energy of photovoltaic generating system, also can reduce the output electric energy of public electric wire net simultaneously.
Further, without the need to installing extra switching circuit in the present embodiment, and the controller that can be had by photovoltaic generating system self just can regulate the power of photovoltaic generating system, therefore also without the need to extra controller, therefore, compared to existing technology, reduce cost, realize also easier.
In the present embodiment, photovoltaic generating system can comprise at least one photovoltaic DC-to-AC converter.
In the present embodiment, when there being reverse power transmission, just reducing photovoltaic power generation system output power, when there is no reverse power transmission, just raising the power output of photovoltaic generating system.The fluctuation of photovoltaic power generation system output power will be caused, in fact, the power output of all right stable regulation photovoltaic generating system further.Especially by when the testing result that step S101 detects whether reverse power transmission is no, judge on photovoltaic generating system, whether a cycle is downrating, if, then send the 3rd control signal to described photovoltaic generating system, if not, then perform and describedly send the second control signal to described photovoltaic generating system; Described 3rd control signal controls described photovoltaic generating system and keeps current power to run.That is, if when there is no reverse power transmission, if a upper periodic light photovoltaic generating system is downrating, current power is now just kept to run, if a upper periodic light photovoltaic generating system is not downrating, but keep Power operation or power per liter to run, now run with regard to power per liter.This makes it possible to realize regulating this operation according to the ruuning situation before photovoltaic generating system, thus be no longer run with regard to power per liter as long as no adverse current, but according to circumstances select to be power per liter or maintenance Power operation, thus stabilize the power output of photovoltaic generating system.
Specifically can realize by arranging counterflow-preventing flag bit, when sending the first control signal to described photovoltaic generating system, arranging counterflow-preventing flag bit is first; When sending the 3rd control signal to described photovoltaic generating system, arranging counterflow-preventing flag bit is second.Therefore, if when counterflow-preventing flag bit is first, just illustrate that a upper periodic light photovoltaic generating system is downrating, if counterflow-preventing flag bit is second, just illustrate that a upper periodic light photovoltaic generating system is not downrating.
In fact, the present invention can also be arranged further, and after making photovoltaic generating system first keep current power to run a period of time after adverse current disappearance being detected, power per liter of reruning, is illustrated below by an embodiment.
Refer to Fig. 2, present invention also offers the second embodiment of Countercurrent prevention control method, in the present embodiment, after in parallel with public electric wire net by photovoltaic generating system, jointly power to load circuit.
Described method comprises:
S201 is performed with some cycles circulation.
S201: whether detect photovoltaic generating system to the reverse power transmission of public electric wire net by adverse current detecting unit, if, then illustrate this detect in be tested with photovoltaic generating system to the reverse power transmission of public electric wire net, now perform S202, if not, then illustrate in this detects, do not detect that photovoltaic generating system 301 is to the reverse power transmission of public electric wire net 304, now performs S203.
S202: send the first control signal to described photovoltaic generating system, arranging counterflow-preventing flag bit flag is first, namely arranges flag=1, and set timer is initial value and starts timing.Described first control signal controls described photovoltaic generating system downrating.First control signal can also control the timeconstantτ 1 of n photovoltaic DC-to-AC converter downrating in photovoltaic generating system according to the electric energy size of the reverse power transmission detected, thus realizes regulating the speed of falling power.After step S202 executes, perform S208.
In fact, in step S202, setting timer start timing, is keep power operating states timing for photovoltaic generating system.Further, when having downrating at every turn, be all initial value by set timer, make timer restart timing.
S203: judge that counterflow-preventing flag bit is first or second, if first, i.e. flag=1, then perform S204, if be second, i.e. flag=0, then performs S207.
S204: now counterflow-preventing flag bit is first, sends the 3rd control signal to described photovoltaic generating system, and described 3rd control signal controls described photovoltaic generating system and keeps current power to run.
S205: judge whether described timer timing reaches preset time T, if so, then performs S206, if not, then performs S208.
When judging that timer reaches preset time T in step S205, just perform S206, namely arranging flag bit is second, now shows that photovoltaic generating system has kept Power operation preset time T till now from downrating last time.
S206: arranging counterflow-preventing flag bit is second, namely arranges flag=0.That is, after judging that photovoltaic generating system keeps current power to run preset time T, just counterflow-preventing flag bit is set to second, then, when next time is detected, if there is not reverse power transmission, photovoltaic generating system runs with regard to power per liter.
After step S206 executes, perform S208.
S207: now counterflow-preventing flag bit is second, sends the second control signal to described photovoltaic generating system.Described second control signal controls described photovoltaic generating system power per liter and runs.The electric energy size that second control signal can also export according to the public electric wire net detected controls the timeconstantτ 2 that n photovoltaic DC-to-AC converter power per liter in photovoltaic generating system is run, thus realizes the speed regulating power per liter.After step S207 executes, perform S208.
S208: terminate this and detect, return when next cycle starts and perform S201, thus realize performing the circulation of S201.
Wherein, the first control signal, the second control signal and the 3rd control signal can be sent by the photovoltaic DC-to-AC converter own controller in photovoltaic generating system.Specifically can call counterflow-preventing program by photovoltaic DC-to-AC converter own controller in the timer period of each circulation to realize, after step S208 performs, represent that this counterflow-preventing routine call terminates, wait for that this counterflow-preventing program is called in next cycle recirculation.The display screen of photovoltaic DC-to-AC converter can also show the cycle time of S201 cycle detection, timeconstantτ 1, τ 2, and preset time T.
Visible, in the present embodiment, when judging there is no reverse power transmission, continue to judge that counterflow-preventing flag bit flag is 1 or 0.As flag=1, illustrate that photovoltaic generating system was fall power stage in a upper cycle, or kept current power output timing not have to reach preset time T in a upper cycle, now, keep the power output of photovoltaic generating system with stable output.As flag=0, illustrate that on photovoltaic generating system, a cycle is that power per liter exports, or kept current power output timing to reach preset time T in a upper cycle, now, photovoltaic generating system power per liter exports.Therefore, in the present embodiment, not only electric energy needed for the generating electric energy of real-time matching photovoltaic generating system and load circuit, simultaneously, as long as be not judge do not have reverse power transmission to export with regard to power per liter, but be power per liter or maintenance power output according to the condition adjudgement before photovoltaic generating system, thus the output of further light stable photovoltaic generating system.
As shown in Figure 3, present invention also offers the specific embodiment of counterflow-preventing control device, in the present embodiment, described device comprises: adverse current detecting unit 301 and adverse current control unit 302.
Whether adverse current control unit 302 is for passing through adverse current detecting unit 301 with some cycles cycle detection photovoltaic generating system 303 to the reverse power transmission of public electric wire net 305, if, then adverse current control unit 302 sends the first control signal to photovoltaic generating system 303, if not, then adverse current control unit 302 sends the second control signal to photovoltaic generating system 303.
Can be specifically detect the outflow of public electric wire net by adverse current detecting unit or flow into energy information, the information this detected returns to adverse current control unit, is judged whether to occur reverse power transmission by adverse current control unit.
First control signal controls described photovoltaic generating system 303 downrating, and described second control signal controls described photovoltaic generating system 303 power per liter and runs; Described photovoltaic generating system 303 backward load circuit 304 in parallel with described public electric wire net 305 is powered.
Photovoltaic generating system can comprise at least one photovoltaic DC-to-AC converter.Such as, the photovoltaic generating system shown in Fig. 3 comprises n photovoltaic DC-to-AC converter arranged side by side, namely photovoltaic DC-to-AC converter 1, photovoltaic DC-to-AC converter 2 ..., photovoltaic DC-to-AC converter n.
In the present embodiment, adverse current detecting unit 301, for detecting whether there is reverse power transmission, is specifically as follows the checkout equipments such as instrument transformer, electric energy meter or bidirectional measuring table.
Adverse current control unit 302 can for realizing the device of controlling functions, and such as, adverse current control unit can be the control device such as single-chip microcomputer, DSP, ARM, FPGA/CPLD.It can be specifically the controller that photovoltaic DC-to-AC converter self has.
Preferably, described adverse current control unit 302 also for, when whether to the testing result of public electric wire net reverse power transmission be no to described adverse current detecting unit 301 if detecting photovoltaic generating system, judge on photovoltaic generating system 303, whether a cycle is downrating, if, then send the 3rd control signal to described photovoltaic generating system 303, if not, then perform and describedly send the second control signal to described photovoltaic generating system 303; Described 3rd control signal controls described photovoltaic generating system 303 and keeps current power to run.
Preferably, described adverse current control unit also for, when sending the first control signal to described photovoltaic generating system, arranging counterflow-preventing flag bit is first; When sending the 3rd control signal to described photovoltaic generating system, arranging counterflow-preventing flag bit is second.
Then describedly judge on photovoltaic generating system, whether a cycle is that downrating is specially: judge that counterflow-preventing flag bit is first or second, if be first, then describedly judge that cycle on photovoltaic generating system be whether the judged result of downrating is yes, if be second, then describedly judge that cycle on photovoltaic generating system be whether the judged result of downrating is no.
Preferably, described adverse current control unit 302 also for, when arranging counterflow-preventing flag bit and being first, set timer is initial value and starts timing.
Described setting before counterflow-preventing flag bit is second also comprises: judge whether described timer timing reaches Preset Time, and if so, then performing the described counterflow-preventing flag bit that arranges is second.
Preferably, described adverse current control unit 302 also for, when detecting whether reverse to the public electric wire net power transmission of photovoltaic generating system, detected the electric energy size flowing to or flow out public electric wire net by adverse current detecting unit 301.
Described first control signal controls the speed of described photovoltaic generating system downrating according to the electric energy size detected, described second control signal controls the speed of described photovoltaic generating system power per liter operation according to the electric energy size detected.
It should be noted that, the countercurrent controller that the embodiment of any one the adverse current control method provided in the present invention all can provide in the present invention realizes.Further, the embodiment of countercurrent controller describes relatively simpler, and relevant part can reference method embodiment.
The above is only the preferred embodiment of the present invention; it should be pointed out that for those skilled in the art, under the premise without departing from the principles of the invention; can also make some improvements and modifications, these improvements and modifications also should be considered as protection scope of the present invention.
Claims (8)
1. a Countercurrent prevention control method, is characterized in that, described method comprises:
With some cycles cycle detection photovoltaic generating system whether to the reverse power transmission of public electric wire net, if, then send the first control signal to described photovoltaic generating system, if not, judge on photovoltaic generating system, whether a cycle is downrating, if so, then send the 3rd control signal to described photovoltaic generating system, if not, then the second control signal is sent to described photovoltaic generating system;
Described first control signal controls described photovoltaic generating system downrating, and described second control signal controls described photovoltaic generating system power per liter and runs, and described 3rd control signal controls described photovoltaic generating system and keeps current power to run;
Described photovoltaic generating system backward load circuit in parallel with described public electric wire net is powered.
2. method according to claim 1, is characterized in that, described method also comprises:
When sending the first control signal to described photovoltaic generating system, arranging counterflow-preventing flag bit is first; When sending the 3rd control signal to described photovoltaic generating system, arranging counterflow-preventing flag bit is second;
Then describedly judge on photovoltaic generating system, whether a cycle is that downrating is specially: judge that counterflow-preventing flag bit is first or second, if be first, then describedly judge that cycle on photovoltaic generating system be whether the judged result of downrating is yes, if be second, then describedly judge that cycle on photovoltaic generating system be whether the judged result of downrating is no.
3. method according to claim 2, is characterized in that, described method also comprises: when arranging counterflow-preventing flag bit and being first, set timer is initial value and starts timing;
Described setting before counterflow-preventing flag bit is second also comprises:
Judge whether described timer timing reaches Preset Time, if so, then performing the described counterflow-preventing flag bit that arranges is second.
4. method according to claim 1, is characterized in that, during whether reverse to the public electric wire net power transmission of described detection photovoltaic generating system, also comprises: detect the electric energy size flowing to or flow out public electric wire net;
Described first control signal controls the speed of described photovoltaic generating system downrating according to the electric energy size detected, described second control signal controls the speed of described photovoltaic generating system power per liter operation according to the electric energy size detected.
5. method according to claim 1, is characterized in that, whether described detection photovoltaic generating system is specially to the reverse power transmission of public electric wire net: whether detect photovoltaic generating system to the reverse power transmission of public electric wire net by instrument transformer, electric energy meter or bidirectional measuring table.
6. a counterflow-preventing control device, is characterized in that, described device comprises: adverse current detecting unit and adverse current control unit;
Described adverse current control unit be used for by described adverse current detecting unit with some cycles cycle detection photovoltaic generating system whether to the reverse power transmission of public electric wire net, if, then send the first control signal to described photovoltaic generating system, if not, judge on photovoltaic generating system, whether a cycle is downrating, if so, then send the 3rd control signal to described photovoltaic generating system, if not, then the second control signal is sent to described photovoltaic generating system;
Described first control signal controls described photovoltaic generating system downrating, and described second control signal controls described photovoltaic generating system power per liter and runs, and described 3rd control signal controls described photovoltaic generating system and keeps current power to run;
Described photovoltaic generating system backward load circuit in parallel with described public electric wire net is powered.
7. device according to claim 6, is characterized in that, described adverse current detecting unit is instrument transformer, electric energy meter or bidirectional measuring table.
8. device according to claim 6, is characterized in that, described photovoltaic generating system comprises at least one photovoltaic DC-to-AC converter.
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| Title |
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| 单片机多任务延时程序设计;朱彩霞等;《淮阴工学院学报》;20090228;第18卷(第1期);第1节第5段，图1 * |
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