Content of the invention
Embodiments provide online operation/cutting method, the apparatus and system of a kind of photovoltaic generation unit, reduce photovoltaicDash current during generator unit switching is so that the photovoltaic generation unit departing from DC master row smoothly puts into photovoltaic DC onlineElectric power system.
Embodiments of the invention adopt the following technical scheme that：
A kind of online operation/cutting method of photovoltaic generation unit, the method includes：
Obtain the busbar voltage of DC master row and the output voltage of DC-DC converter；
Calculate the voltage difference of described busbar voltage and the output voltage of described DC-DC converter；
The relatively amplitude of described voltage difference and preset value；
If described amplitude is less than described preset value, controls described functional switch closure, make described photovoltaic generation unitSwitching enters described DC master row；
If described amplitude is more than or equal to described preset value, big according to described busbar voltage and described output voltageLittle that described output voltage is carried out with charge and discharge is electrically operated, makes described amplitude be less than described preset value.
A kind of online switching device of photovoltaic generation unit, this device is connected to DC-DC converter and DC master rowBetween, this device includes：
Voltage acquisition module, for obtaining the busbar voltage of described DC master row and the defeated of described DC-DC converterGo out voltage；
Computing module, for calculating the voltage difference of described busbar voltage and the output voltage of described DC-DC converter；
Comparison module, for the relatively amplitude of described voltage difference and preset value；
Switching performing module, for when described amplitude is less than described preset value, control described functional switch closure withMake described photovoltaic generation unit switching to described DC master row, when described amplitude is more than or equal to described preset value, rootAccording to the size of described busbar voltage and described output voltage described DC capacitor is carried out with charge and discharge electrically operated, so that described amplitude is less thanDescribed preset value.
A kind of online fling-cut system of photovoltaic generation unit, this system includes：DC-DC converter, above-mentioned technical sideThe online switching device of the photovoltaic generation unit in case, DC master row；
Wherein, the online switching device of described photovoltaic generation unit is used for obtaining busbar voltage and the institute of described DC master rowState the output voltage of DC-DC converter, calculate described busbar voltage and the output voltage of described DC-DC converterVoltage difference, and the relatively amplitude of described voltage difference and preset value, if described amplitude is less than described preset value, control described functionProperty switch closure, make described photovoltaic generation unit switching enter described DC master row；If described amplitude is more than or equal to described pre-If value, then charge and discharge is carried out according to the size of described busbar voltage and described output voltage to described output voltage electrically operated, so thatDescribed amplitude is less than described preset value.
The online operation/cutting method of photovoltaic generation unit provided in an embodiment of the present invention, apparatus and system, by DC master rowVoltage difference control function switch and DC-DC converter between is to determine whether switching enters direct current mother to photovoltaic generation unitRow, can reduce dash current during photovoltaic generation unit switching so that the photovoltaic generation unit departing from DC master row is stableOnline input photovoltaic DC electric power system, thus improving the economic feasibility of public direct-current busbar electric power system, reduces to costlinessDc circuit breaker demand, reduce the Financial cost of public direct-current busbar photovoltaic generating system；Due to the embodiment of the present inventionAvoiding in prior art needed, because part photovoltaic generation unit loses efficacy, the drawbacks of restart photovoltaic power supply system, thus also improvingThe reliability of public direct-current busbar photovoltaic power supply system.
Specific embodiment
Below in conjunction with the accompanying drawings to the online operation/cutting method of photovoltaic generation unit provided in an embodiment of the present invention, apparatus and systemIt is described in detail.
The schematic flow sheet of the online operation/cutting method of the photovoltaic generation unit that Fig. 1 provides for one embodiment of the invention；AsShown in Fig. 1, the embodiment of the present invention comprises the steps：
Step 101：Obtain the busbar voltage of DC master row and the output electricity of DC-DC converter (DC/DC changer)Pressure.
Step 102：Calculate the voltage difference of busbar voltage and the output voltage of DC-DC converter.
Step 103：The amplitude of comparison voltage difference and preset value, if amplitude is less than preset value, execution step 104, if amplitudeMore than or equal to preset value, execution step 105.
Step 104：Control function switch closure, makes photovoltaic generation unit switching enter DC master row.
Step 105：Charge and discharge is carried out according to the size of busbar voltage and output voltage to output voltage electrically operated, so that amplitudeLess than preset value.
The online operation/cutting method of photovoltaic generation unit provided in an embodiment of the present invention, by DC master row and DC-to-dcVoltage difference control function between changer switchs to determine that whether switching enters DC master row to photovoltaic generation unit, can reduceDash current during photovoltaic generation unit switching is so that the photovoltaic generation unit departing from DC master row smoothly puts into photovoltaic onlineDC power-supply system, thus improve the economic feasibility of public direct-current busbar electric power system, reducing and expensive direct current is brokenThe demand of road device, reduces the Financial cost of public direct-current busbar photovoltaic generating system.Further, since the embodiment of the present invention avoidsNeeded, because part photovoltaic generation unit lost efficacy, the drawbacks of restart photovoltaic power supply system in prior art, therefore also improved public affairsThe reliability of DC master row photovoltaic power supply system altogether.
The schematic flow sheet of the online operation/cutting method of the photovoltaic generation unit that Fig. 2 provides for another embodiment of the present invention；As shown in Fig. 2 on the basis of the technical scheme of above-mentioned embodiment illustrated in fig. 1 and Advantageous Effects, embodiment of the present invention bagInclude following steps：
Step 201, the acquisition busbar voltage of DC master row and the output voltage of DC-DC converter, execution step202.
Wherein, in step 201, busbar voltage V of DC master row can be gathered by voltage sensordcN, direct current-straightThe output voltage V of current converterdc_bus.
The voltage difference of the output voltage of step 202, calculating busbar voltage and DC-DC converter, execution step 203.
Wherein, in step 202., busbar voltage and output voltage difference between the two can be Δ Vdc=Vdc_bus-VdcNOr Δ Vdc=-Vdc_bus+VdcN.
Step 203, the amplitude of voltage difference and preset value are compared, whether the amplitude determining voltage difference is less than defaultValue, if amplitude is less than preset value, execution step 204, if amplitude is more than or equal to preset value, execution step 205.
Wherein, in step 203, in difference DELTA VdcAmplitude | Vdc| in the case of preset value, can also be furtherRelatively | Vdc| with preset value Δ Vdc_set, determine the need for for photovoltaic generation unit carrying out online switching by comparative result.
Step 204, photovoltaic generation unit switching is entered DC master row, flow process terminates.
Wherein, in step 204, the switching of photovoltaic generation unit can be completed by closure function switch.By work(Property can switch the voltage difference that can reduce between DC master row and DC-DC converter, thus reducing dash current to photovoltaicThe impact of generator unit.
Step 205, that according to the size of busbar voltage and output voltage, output voltage is carried out with charge and discharge is electrically operated, so that amplitudeLess than preset value, i.e. busbar voltage is compared with output voltage, if Vdc_bus>VdcN, execution step 206, if Vdc_bus<VdcN, execution step 207.
Step 206, to DC-DC converter send instruction make DC-DC converter absorb photovoltaic battery panel energyAmount, thus charging for DC capacitor, improves the output voltage V of DC-DC converter furtherdcN.And execution step 202.
Step 207, discharged by relief circuit, to reduce output voltage, until the busbar voltage of DC master rowVdc_busOutput voltage V with DC-DC converterdcNThe amplitude of voltage difference between the two is less than preset value, execution step204；Alternatively, the output voltage of DC-DC converter can also be reduced by the self discharge of DC capacitor.By off-loadLoop or the self discharge of DC capacitor, can reduce the output voltage of DC-DC converter, it is to avoid larger dash currentImpact to photovoltaic generation unit.
On the basis of above-mentioned Fig. 1 or embodiment illustrated in fig. 2, if photovoltaic generation unit switching is entered after DC master row,Can also carry out following steps：
Whether detection photovoltaic generation unit meets the condition that needs are disconnected with DC master row；Wherein it is desired to the condition disconnectingCould be arranged to：By the electric current between photovoltaic generation unit and DC master row or electric voltage exception, photovoltaic generation unit is gone outExisting fault, or, due to needing that photovoltaic generation unit is overhauled etc..Further, the condition needing disconnection can be automaticIdentification can also be arranged by way of artificial.The embodiment of the present invention does not do specific restriction to the condition disconnecting, as long as needingPhotovoltaic generation unit and DC master row are disconnected.
If meeting the condition of disconnection, by break function switch, photovoltaic generation unit is disconnected with DC master row,And photovoltaic generation unit is labeled as inefficacy photovoltaic generation unit.By this operation, public direct-current busbar light can not affectedOn the premise of the normal operation of photovoltaic generating system, it is to avoid the danger that photovoltaic generation unit brings to surrounding.
Further, in photovoltaic generation unit after functional switch with DC master row disconnection, detect photovoltaic generation listWhether unit meets the condition that needs are connected with DC master row；Wherein it is desired to the condition connecting could be arranged to：Photovoltaic generation unitElectric current and DC master row between or voltage are recovered normal, photovoltaic generation unit has been overhauled and has finished, in this kindAll photovoltaic generation unit can be connected with DC master row under situation.Likewise, the embodiment of the present invention is not done to the condition connectingSpecific restriction, as long as can need to be connected photovoltaic generation unit with DC master row.
If meeting the condition of connection, execute the step 101～step 105 in above-mentioned embodiment illustrated in fig. 1, or executionStep 201～step 205 in above-mentioned embodiment illustrated in fig. 2, thus the photovoltaic generation unit of inefficacy is incorporated to normal operationPublic direct-current busbar photovoltaic generating system.
The structural representation of the online switching device of the photovoltaic generation unit that Fig. 3 provides for one embodiment of the invention；ShouldOnline switching device is connected between DC-DC converter and DC master row, as shown in figure 3, the embodiment of the present invention includes：
Voltage acquisition module 31, for obtaining the busbar voltage of DC master row and the output voltage of DC-DC converter；
Computing module 32, for calculating the voltage difference of busbar voltage and the output voltage of DC-DC converter；
Comparison module 33, the amplitude for comparison voltage difference and preset value；
Switching performing module 34, for when amplitude is less than preset value, control function switch is closed so that photovoltaic is sent outElectric unit switching enters DC master row, when amplitude is more than or equal to preset value, according to the size of busbar voltage and output voltageDC capacitor is carried out with charge and discharge electrically operated, make amplitude be less than preset value.
The online switching device of photovoltaic generation unit provided in an embodiment of the present invention, switching performing module 34 is passed through to calculate mouldVoltage difference between DC master row that block 32 obtains and DC-DC converter determines whether switching enters direct current to photovoltaic generation unitBusbar, can reduce dash current during photovoltaic generation unit switching so that the photovoltaic generation unit departing from DC master row is steadyOnline input photovoltaic DC electric power system, thus improving the economic feasibility of public direct-current busbar electric power system, reduce to highThe demand of expensive dc circuit breaker, reduces the Financial cost of public direct-current busbar photovoltaic generating system；Because the present invention is implementedExample avoids in prior art to be needed to restart the disadvantage of common DC master row photovoltaic power supply system because part photovoltaic generation unit loses efficacyEnd, thus also improve the reliability of public direct-current busbar photovoltaic power supply system.
The structural representation of the online switching device of the photovoltaic generation unit that Fig. 4 provides for another embodiment of the present invention；As shown in figure 4, on the basis of the technical scheme of above-mentioned embodiment illustrated in fig. 3 and Advantageous Effects, this online switching deviceAlso include：
Sending module 35, for DC master row busbar voltage be more than DC-DC converter output voltage when, toDC-DC converter sends instruction makes DC-DC converter absorb the energy of photovoltaic battery panel, thus filling for DC capacitorElectricity；
Relief circuit 36, for when busbar voltage is less than output voltage, being discharged by relief circuit 36, to reduceOutput voltage.Further, relief circuit 36 includes the resistance being connected in series and switch.By the electric discharge of relief circuit, permissibleReduce the output voltage of DC-DC converter, it is to avoid the impact to photovoltaic generation unit for the larger dash current.ReplaceableGround, can also arrange DC capacitor in online switching device, reduce DC-DC converter by the self discharge of DC capacitorOutput voltage, it is to avoid the impact to photovoltaic generation unit for the larger dash current.
Further, online switching device also includes：
First detection module 37, for detecting whether described photovoltaic generation unit is met needs and broken with described DC master rowThat opens is pre-conditioned；
If meeting described pre-conditioned, switching performing module 34 is passed through break function switch and is made photovoltaic generation unitDisconnect with described DC master row.
Further, online switching device also includes：
Second detection module 38, for detecting whether described inefficacy photovoltaic generation unit meets needs and described DC master rowThe condition connecting；
If meeting the condition of described connection, by voltage acquisition module 31 obtain the busbar voltage of DC master row with straightThe output voltage of stream-DC converter, computing module 32 calculates the electricity of busbar voltage and the output voltage of DC-DC converterPressure reduction, by this voltage difference, switching performing module 34 determines whether switching enters DC master row to photovoltaic generation unit, thus will lose efficacyPhotovoltaic generation unit be incorporated to the common DC master row photovoltaic generating system of normal operation.
It follows that the embodiment of the present invention can be by being reduced to high using conventional relief circuit, resistance, DC capacitorThe demand of expensive dc circuit breaker, therefore reduces Financial cost.
The structural representation of the online fling-cut system of the photovoltaic generation unit that Fig. 5 provides for one embodiment of the invention；AsShown in Fig. 5, the online fling-cut system of photovoltaic generation unit provided in an embodiment of the present invention includes：DC-DC converter 51, onState the online switching device 52 of photovoltaic generation unit in Fig. 3 or embodiment illustrated in fig. 4, DC master row 53.
Wherein, the voltage acquisition module 31 in the online switching device 52 of photovoltaic generation unit obtains the mother of DC master row 53Line voltage and the output voltage of DC-DC converter 51, computing module 32 calculates busbar voltage and DC-DC converterThe voltage difference of output voltage, the amplitude of comparison module 33 comparison voltage difference and preset value, when amplitude is less than preset value, then switchingPerforming module 34 control function switch 523 closure, makes photovoltaic generation unit switching enter DC master row；It is more than in amplitude or waitWhen preset value, switching performing module 34 carries out discharge and recharge according to the size of busbar voltage and output voltage to DC capacitor 521Operation, so that amplitude is less than preset value.
In embodiments of the present invention, as shown in figure 5, photovoltaic battery panel 54 and header box 55 and DC master row grid-connecting apparatus56 collection is collectively referred to as photovoltaic generation unit.Wherein, online switching device 52 can be arranged in DC master row grid-connecting apparatus 56.
Further, as shown in figure 5, online switching device 52 also includes：DC capacitor 521, relief circuit 522, functionProperty switch 523, online switching device 52 carries out discharge and recharge behaviour according to the size of busbar voltage and output voltage to DC capacitor 521Make, so that the amplitude of the voltage difference between busbar voltage and output voltage is less than preset value；It is less than output voltage in busbar voltage,Then online switching device 52 passes through to control relief circuit 522 to be discharged, to reduce output voltage；In online switching device 52With disconnecting, switching performing module 34 determines whether photovoltaic generation unit is thrown by the closure of voltage difference control function switch 523Incision DC master row；By this circuit structure, the embodiment of the present invention can be using conventional chopper, catalyst, isolationSwitch, as the functional switch in the embodiment of the present invention, reduces the demand of the dc circuit breaker of costliness, reduces economic one-tenthThis.
When the busbar voltage of DC master row 53 is more than the output voltage of DC-DC converter 51, online switching device52 also send instruction to DC-DC converter 51 makes DC-DC converter 51 absorb the energy of photovoltaic battery panel, thus beingDC capacitor 521 charges.It follows that the online switching device 52 in the embodiment of the present invention is with DC-DC converter 51 notOnly voltage is transmitted by pressure-wire, carry out data transmission also by communication line.For example, the transmission mould in online switching device 52Block 35 sends instruction by communication line to DC-DC converter 51 makes DC-DC converter 51 absorb photovoltaic battery panelEnergy, thus charging for DC capacitor 521.
For the Advantageous Effects of the vivider explanation embodiment of the present invention, below by Fig. 6～Figure 13 to the present inventionThe Advantageous Effects of embodiment illustrate.
Fig. 6 be when output voltage is for 0V by direct for photovoltaic generation unit switching the voltage oscillogram to after DC master row,Fig. 7 be when output voltage is for 0V by direct for photovoltaic generation unit switching the current waveform figure to after DC master row, Fig. 8 is when defeatedGo out voltage for during 0V by the embodiment of the present invention by the voltage oscillogram after photovoltaic generation unit switching to DC master row, Fig. 9 isWhen output voltage is for 0V by the embodiment of the present invention by the current waveform figure after photovoltaic generation unit switching to DC master row.
Wherein, the abscissa express time in Fig. 6, unit is the second (s), and vertical coordinate represents voltage, and unit is volt (V),Wherein, solid line represents the output voltage V of DC-DC converterdcN, dotted line represents busbar voltage Vdc_bus；Abscissa in Fig. 7Express time, vertical coordinate represents electric current, and unit is ampere (A).From Fig. 6 and Fig. 7, work as VdcNFor 0V, Vdc_busFor 1000VWhen, according to direct switching of the prior art, then the dash current Ic of photovoltaic generation unit_rushUp to upper Wan An.
Abscissa express time in Fig. 8, unit is the second (s), and vertical coordinate represents that (wherein, solid line represents direct current-straight to voltageThe output voltage of current converter, dotted line represents busbar voltage), unit is volt (V)；Abscissa express time in Fig. 9, indulges and sitsMark represents electric current, and unit is that (wherein, solid line represents the dash current Ic_rush on DC master row to ampere (A), and dotted line represents rightCharging current Ic_charging of DC capacitor).From Fig. 8 and Fig. 9, work as VdcNFor 0V, Vdc_busDuring for 1000V, by adoptingWith the online switching device of photovoltaic generation unit provided in an embodiment of the present invention, can be seen that dash current from waveform thereinRatio is shallower, and less, only 150A about, less dash current during photovoltaic generation unit switching, it is achieved thereby that lightVolt generator unit smoothly puts into photovoltaic DC electric power system online.
Figure 10 be when output voltage is for 1500V by direct for photovoltaic generation unit switching the voltage waveform to after DC master rowFigure, Figure 11 be when output voltage is for 1500V by direct for photovoltaic generation unit switching the current waveform figure to after DC master row, figure12 is by the voltage wave after photovoltaic generation unit switching to DC master row when output voltage is for 1500V by the embodiment of the present inventionShape figure, Figure 13 be when output voltage is for 1500V after the embodiment of the present invention is by photovoltaic generation unit switching to DC master rowCurrent waveform figure.
Wherein, the abscissa express time in Figure 10, unit is the second (s), and vertical coordinate represents that (wherein, solid line represents voltageThe output voltage of DC-DC converter, dotted line represents busbar voltage), unit is volt (V)；Abscissa in Figure 11 representsTime, vertical coordinate represents electric current, and unit is ampere (A).From Figure 10 and Figure 11, work as VdcNFor 1500V, Vdc_busFor 1000VWhen, according to direct switching of the prior art, then the dash current Ic_rush of photovoltaic generation unit, up to goes up Wan An.
Abscissa express time in Figure 12, unit be the second (s), vertical coordinate represent voltage (wherein, solid line represent direct current-The output voltage of DC converter, dotted line represents busbar voltage), unit is volt (V)；Abscissa express time in Figure 13,Vertical coordinate represents electric current, and unit is ampere (A), and wherein, solid line represents the dash current Ic_rush on DC master row, dotted line tableShow charging current Ic_charging to DC capacitor.From Figure 12 and Figure 13, work as VdcNFor 1500V, Vdc_busFor 1000VWhen, by the online switching device using photovoltaic generation unit provided in an embodiment of the present invention, can be seen that from waveform thereinBefore switching, after DC capacitor electric discharge, voltage reduces, and completes switching when voltage difference is less, dash current Ic_rush is less, onlyThere is 90A, it is achieved thereby that photovoltaic generation unit smoothly puts into photovoltaic DC electric power system online.
The above, the only specific embodiment of the present invention, but protection scope of the present invention is not limited thereto, and anyThose familiar with the art the invention discloses technical scope in, change or replacement can be readily occurred in, all should containCover within protection scope of the present invention.Therefore, protection scope of the present invention should be defined by described scope of the claims.