CN104158223A - Grid-connected inverter control method and device - Google Patents
Grid-connected inverter control method and device Download PDFInfo
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- CN104158223A CN104158223A CN201410439901.0A CN201410439901A CN104158223A CN 104158223 A CN104158223 A CN 104158223A CN 201410439901 A CN201410439901 A CN 201410439901A CN 104158223 A CN104158223 A CN 104158223A
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Abstract
The invention provides a grid-connected inverter control method and device. The actual bus voltage of an inverter bus is monitored in real time, and when it is determined that the absolute value of a first difference value of the actual bus voltage and the target bus voltage is larger than a first voltage threshold, the target current value of an inductance element in an inverter is calculated through the first difference value, wherein the target bus voltage is the minimum voltage meeting the success inversion of the inverter; then, the current current of the inductance element is adjusted according to the target current value so that the absolute value of the difference value of the actual bus voltage and the target bus voltage can be not larger than the first voltage threshold, the occurrence that a capacitor connected to the inverter bus in parallel is damaged due to the fact that the voltage of the inverter bus is too high is avoided, and the problem that in the prior art, due to the fact that the voltage of the inverter bus is too high, the inversion conversion efficiency is reduced is solved.
Description
Technical field
The present invention relates to the technical field of inverter in grid-connected photovoltaic system, more particularly, relate to a kind of control method of grid-connected inverter and device.
Background technology
At present, in grid-connected photovoltaic system, when the PV voltage of PV plate output is less than the required minimal reverse variable bus voltage of inversion, in order to guarantee that inversion busbar voltage reaches the required minimum voltage of inversion, so that inverter is normally worked, be all at PV (Photo Voltaic, photocell) plate output access DC/DC converter conventionally, to processings of boosting of the PV voltage of PV plate output, thereby make the voltage after processing reach the required minimum voltage value of inversion.
Yet, for existing this inverter, when the PV voltage of PV plate output is greater than the required minimal reverse variable bus voltage of inversion, the DC/DC converter with boost function will quit work, and now, PV plate is directly inversion bussed supply by bypass mode, inversion busbar voltage equals PV voltage, although met the required minimum voltage of inversion,, due to the too high conversion efficiency that will reduce inversion of now inversion busbar voltage.
Summary of the invention
In view of this, the invention provides a kind of control method of grid-connected inverter and device, solved in prior art because of the too high technical problem that reduces inversion efficiency of inversion busbar voltage.
To achieve these goals, the application provides following technical scheme:
A control method of grid-connected inverter, described method comprises:
The actual bus voltage of monitoring inverter bus;
Calculate the first difference between described actual bus voltage and target busbar voltage, described target busbar voltage is the minimum voltage that meets described inverter success inversion;
Whether the absolute value that judges described the first difference is greater than the first voltage threshold;
If so, utilize described the first difference to calculate the target current value of inductance element in described inverter;
According to described target current value, regulate the current electric current of inductance element in described inverter until the absolute value of the difference between the actual bus voltage monitoring and described target busbar voltage is not more than described the first voltage threshold.
Preferably, the current electric current of the inductance element in the described inverter of described adjusting comprises:
When described actual bus voltage is greater than described target busbar voltage, increase the current electric current of inductance element in described inverter;
When described actual bus voltage is less than described target busbar voltage, reduce the current electric current of inductance element in described inverter.
Preferably, before the actual bus voltage of monitoring inverter bus, described method also comprises:
Monitor the actual PV voltage of the PV plate output corresponding with described inverter;
Calculate the second difference between described actual PV voltage and default target busbar voltage.
Preferably, when judging described the second difference, is greater than zero and is greater than described the first voltage threshold, and when described actual bus voltage reaches default expectation PV voltage, described method also comprises:
Described PV plate is carried out to MPPT scanning, determine the actual expectation PV voltage of described PV plate;
The 3rd difference of the current actual PV voltage of the described PV plate that calculating detects and described actual expectation PV voltage;
Whether the absolute value that judges described the 3rd difference is greater than second voltage threshold value;
If, utilize the current electric current of inductance element in the DC/DC converter that described the 3rd difference adjustment is connected with described PV plate output, until the absolute value of the difference of the actual PV voltage detecting and described actual expectation PV voltage is not more than described second voltage threshold value.
Preferably, when judge described the second difference be less than zero and absolute value be greater than described the first voltage threshold, and while making the absolute value of described the first difference be not more than described the first voltage threshold by described actual PV boost in voltage is processed, described method also comprises:
Described PV plate is carried out to MPPT scanning, determine the actual expectation PV voltage of described PV plate;
The 4th difference of the current actual PV voltage of the described PV plate that calculating detects and described actual expectation PV voltage;
Whether the absolute value that judges described the 4th difference is greater than tertiary voltage threshold value;
If, utilize the current electric current of inductance element in the DC/DC converter that described the 4th difference adjustment is connected with described PV plate output, until the absolute value of the difference of the actual PV voltage detecting and described actual expectation PV voltage is not more than described tertiary voltage threshold value.
Preferably, described method also comprises:
Detect the grid-connected power of bearing power and described inverter;
When judging described grid-connected power and be greater than described bearing power, described actual bus voltage is depressurized to the specified charging voltage of energy-storage battery, be delivered to energy-storage battery;
When judging described grid-connected power and be less than described bearing power, the boost in voltage of energy-storage battery output, to described target busbar voltage, is delivered to described inverter.
Preferably, described energy-storage battery is charged or described energy-storage battery discharge process in, described method also comprises:
Monitor the physical holding of the stock capacity of described energy-storage battery;
When described actual energy storage is deposited capacity and reached the maximum storage capacity of described energy-storage battery, described energy-storage battery is stopped to charging;
When described physical holding of the stock capacity reaches the minimum storage volume of described energy-storage battery, control described energy-storage battery and stop electric discharge.
A combining inverter control system, described system comprises PV plate and the storage capacitor that is connected in parallel on inverter input terminal, described system also comprises:
Input is connected with PV plate output, and output is connected with described inverter input terminal, has and boosts and buck functionality, and described PV plate is carried out to MPPT scanning, determines a DC/DC converter of the actual expectation PV voltage of described PV plate;
Be connected the first monitoring device of the actual bus voltage of monitoring inverter bus with described storage capacitor two ends;
Be connected with described inverter with described the first monitoring device, receive the described actual bus voltage of this first monitoring device output, and calculate the first difference between described actual bus voltage and target busbar voltage, when judging the absolute value of described the first difference and be greater than the first voltage threshold, utilize this first difference to calculate the target current value of inductance element in described inverter, and the described target current value of foundation regulates the current electric current of inductance element in described inverter, until the absolute difference between the actual bus voltage monitoring and described target busbar voltage is not more than the first control device of described the first voltage threshold,
Wherein, described target busbar voltage is the minimum voltage that meets described inverter success inversion.
Preferably, described system also comprises:
Be connected with described PV plate output, monitor the second monitoring device of the actual PV voltage of described PV plate output;
Be connected with a described DC/DC converter with described the second monitoring device, calculate the 3rd difference of actual PV voltage with the actual expectation PV voltage of the second monitoring device transmission, when judging the absolute value of described the 3rd difference and be greater than second voltage threshold value, utilize described the 3rd difference to adjust the current electric current of inductance element in a described DC/DC converter, until the absolute value of the difference of the actual PV voltage monitoring and described actual expectation PV voltage is not more than the second control device of described second voltage threshold value.
Preferably, described system also comprises:
One end is connected with described inverter input terminal, has the 2nd DC/DC converter boosting with buck functionality;
The energy-storage battery being connected with the other end of described the 2nd DC/DC converter.
As can be seen here, compared with prior art, the application provides a kind of control method of grid-connected inverter and device, by the actual bus voltage of inverter bus is carried out to Real-Time Monitoring, when judging the absolute value of the first difference of this actual bus voltage and target busbar voltage and be greater than the first voltage threshold, utilize this first difference to calculate the target current value of inductance element in inverter, wherein, this target busbar voltage is the minimum voltage that meets described inverter success inversion, afterwards, the present invention is the adjusting to the current electric current of inductance element in this inverter according to this target current value, thereby reduce the first difference between actual bus voltage and target bus, until the absolute value of this first difference is not more than the first voltage threshold, avoided the overtension (being greater than the required minimal reverse variable bus voltage of inversion) because of inversion bus to make to be connected in parallel on the capacitance damage on inversion bus, solved in prior art because of the too high problem that reduces inversion conversion efficiency of inversion busbar voltage simultaneously.
Accompanying drawing explanation
In order to be illustrated more clearly in the embodiment of the present invention or technical scheme of the prior art, to the accompanying drawing of required use in embodiment or description of the Prior Art be briefly described below, apparently, accompanying drawing in the following describes is only embodiments of the invention, for those of ordinary skills, do not paying under the prerequisite of creative work, other accompanying drawing can also be provided according to the accompanying drawing providing.
Fig. 1 is the schematic flow sheet of a kind of grid-connected control method embodiment of the present invention;
Fig. 2 is the control block diagram of a kind of combining inverter of the present invention;
Fig. 3 is the control block diagram of the another kind of combining inverter of the present invention;
Fig. 4 is the schematic flow sheet of the another kind of grid-connected control method embodiment of the present invention;
Fig. 5 is the structured flowchart of a kind of grid-connection control system embodiment of the present invention;
Fig. 6 is the structured flowchart of the another kind of grid-connection control system embodiment of the present invention.
Embodiment
Below in conjunction with the accompanying drawing in the embodiment of the present invention, the technical scheme in the embodiment of the present invention is clearly and completely described, obviously, described embodiment is only the present invention's part embodiment, rather than whole embodiment.Embodiment based in the present invention, those of ordinary skills, not making the every other embodiment obtaining under creative work prerequisite, belong to the scope of protection of the invention.
The application provides a kind of control method of grid-connected inverter and device, by the actual bus voltage of inverter bus is carried out to Real-Time Monitoring, when judging the absolute value of the first difference of this actual bus voltage and target busbar voltage and be greater than the first voltage threshold, utilize this first difference to calculate the target current value of inductance element in inverter, wherein, this target busbar voltage is the minimum voltage that meets described inverter success inversion, afterwards, the present invention regulates the current electric current of inductance element in this inverter according to this target current value, thereby reduce the first difference between actual bus voltage and target bus, until the absolute value of this first difference is not more than the first voltage threshold, avoided making to be connected in parallel on the capacitance damage on inversion bus because of the overtension of inversion bus, solved in prior art because of the too high problem that reduces inversion conversion efficiency of inversion busbar voltage simultaneously.
As shown in Figure 1, be the schematic flow sheet of a kind of control method of grid-connected inverter embodiment of the present invention, the concrete steps of the method can comprise:
Step S101: the actual bus voltage of monitoring inverter bus.
In the present embodiment, the control structure block diagram of inverter as shown in Figure 2, PV (Photo Voltaic, photocell) access of plate output has the DC/DC converter boosting with buck functionality, it is the input of single-phase inverter that the one DC/DC converter output terminal connects inversion bus, wherein, on inversion bus, a capacitor C in parallel is bus capacitor.
The single-phase 230V electrical network of take is example, the minimum inversion busbar voltage that meets reliable inversion is about 230*1.414+25=350V, wherein, 25V is allowance, control structure block diagram based on above-mentioned inverter, in actual applications, the output voltage range of supposing this PV board component is 300V～800V, when PV plate is started working output PV voltage while being low pressure (being that PV voltage is less than minimum inversion busbar voltage), will be by a DC/DC converter to the processing of boosting of PV voltage, conventionally can be after being greater than 350V (being that inversion busbar voltage is greater than 350V), starting inversion side voltage-stabilizing system processes the voltage stabilizing of inversion busbar voltage, control a DC/DC converter simultaneously PV plate is carried out to MPPT scanning, so that PV side voltage-stabilizing system carries out voltage stabilizing processing to this PV voltage.
In like manner, when PV plate is started working output PV voltage while being high pressure (being that PV voltage is greater than minimum inversion busbar voltage), the one DC/DC converter is not worked, PV plate is directly inversion bussed supply by bypass mode, the actual bus voltage of inversion side equals PV voltage, be that actual bus voltage is greater than target busbar voltage, by starting inversion side voltage-stabilizing system, the voltage stabilizing of inversion busbar voltage is processed, control a DC/DC converter simultaneously PV plate is carried out to MPPT scanning, so that PV side voltage-stabilizing system carries out voltage stabilizing processing to this PV voltage.
Thereby, in example of the present invention, for fear of bus capacitor C overtension, damage, or, inversion busbar voltage cannot meet the required minimum voltage of inversion, will carry out Real-Time Monitoring to the voltage on inversion bus, to process in time according to monitoring result.
Step S102: calculate the first difference between this actual bus voltage and target busbar voltage.
Wherein, this target busbar voltage is the minimum voltage that meets inverter success inversion, it can calculate according to the current line voltage detecting, formula used can be: target busbar voltage=current line voltage * 1.414+ allowance, and this allowance can determine according to actual needs, for example, when current line voltage being detected and be 230V, this target busbar voltage can be 230*1.414+25=350V, and wherein, 25V is allowance.
It should be noted that, in actual applications, due to the existence of voltage ripple of power network, thereby target busbar voltage is not fixed on a determined value, and it can change along with the fluctuation of line voltage, but remains the minimum voltage that can meet inversion success demand.
Step S103: whether the absolute value that judges this first difference is greater than the first voltage threshold, if so, performs step S104; If not, return to step S101.
In the present embodiment, for fear of the frequent adjustment to the electric current of inductance element in inverter, can the first voltage threshold be set for the target busbar voltage of current line voltage, when the difference between itself and the actual bus voltage that monitors is within the scope of this first voltage threshold, illustrate that the current busbar voltage on inversion bus has not only met the minimum inversion busbar voltage of reliable inversion, and can not cause damage to the electric capacity being connected in parallel on inversion bus, without carrying out subsequent adjustment operation.
Otherwise, when the difference between this target busbar voltage and the actual bus voltage that monitors is greater than zero and while being greater than the first voltage threshold, illustrate that the current busbar voltage on inversion bus cannot meet the minimum inversion busbar voltage of reliable inversion, inverter cannot normally be worked; And be less than zero and not within the scope of this first voltage threshold when this target busbar voltage and difference between the actual bus voltage that monitors, illustrate that the current busbar voltage on inversion bus is now too high, although met the minimum inversion busbar voltage of reliable inversion, but, the bus capacitor that can make to be connected in parallel on inversion bus damages, thereby affects the safe operation of inverter.
Wherein, the first voltage threshold can determine according to actual needs, and the present invention is not construed as limiting its concrete numerical value.As when needs are strictly controlled inversion busbar voltage, this first voltage threshold can be zero, while only having actual bus voltage on inversion bus to equal target busbar voltage, just without subsequent adjustment, operates.
Step S104: utilize this first difference to calculate the target current value of inductance element in inverter.
Step S105: regulate the current electric current of inductance element in inverter according to this target current value, until the absolute value of the difference between the actual bus voltage monitoring and described target busbar voltage is not more than described the first voltage threshold.
In the present embodiment, when the absolute value of the first difference between the actual bus voltage target busbar voltage corresponding with it is greater than the first voltage threshold, can be by regulating the electric current of inductance element in inverter, to change the energy extracting from inversion bus, change the energy storage of bus capacitor, thereby the voltage of change bus capacitor change inversion busbar voltage.
Concrete, in the situation that the absolute value of the first difference is greater than the first voltage threshold, when actual bus voltage is greater than target busbar voltage, in control inverter, the electric current of inductance element increases, increase the energy extracting from inversion bus, reduce the energy storage of bus capacitor, thereby inversion busbar voltage is reduced, until the difference between the actual bus voltage monitoring and described target busbar voltage is not more than the first voltage threshold; When actual bus voltage is less than target busbar voltage, in control inverter, the electric current of inductance element reduces, reduce the energy extracting from inversion bus, thereby inversion busbar voltage is increased, until the absolute value of the difference between the actual bus voltage monitoring and described target busbar voltage is not more than the first voltage threshold.
Preferably, when the control block diagram of combining inverter is as shown in Figure 3 time, on the basis of the combining inverter control block diagram shown in Fig. 2, in inversion bus access one, there is the 2nd DC/DC converter boosting with buck functionality, and connect an energy-storage battery Bat at the 2nd DC/DC converter output terminal.The control method that the embodiment of the present invention provides is applicable equally, Fig. 3 control structure under, its corresponding control method except protection above steps, can also comprise:
Detect in real time grid-connected power and bearing power, when the grid-connected power detecting is greater than bearing power, the present embodiment will charge to this energy-storage battery Bat, now, because the tank voltage maximum (as 48V energy-storage battery) of energy-storage battery is more much smaller than inversion busbar voltage, thereby, can utilize the 2nd DC/DC converter that actual bus voltage is depressurized to after specified charging voltage (as being 48V by 350V transformation), be delivered to again energy-storage battery Bat, in this process, because inverter side has carried out voltage stabilizing processing to inversion busbar voltage, thereby reduced the transformation ratio of the 2nd DC/DC converter, and then expanded the parts selection of the 2nd DC/DC converter, improved system effectiveness simultaneously.
In like manner, when the grid-connected power detecting is less than bearing power, energy-storage battery Bat in the present embodiment will discharge to inversion busbar voltage, now, because inverter side has carried out voltage stabilizing processing to inversion busbar voltage, thereby reduced the 2nd DC/DC converter to the tank voltage of the energy-storage battery Bat output transformation ratio of processing procedure of boosting, and then expanded the parts selection of the 2nd DC/DC converter, improved system effectiveness.
As another embodiment of the present invention, when each variable collecting (as electric current of inversion busbar voltage, PV voltage, voltage component etc.) reaches its corresponding maximum protection value, can output alarm information.Wherein, this warning message can be the flicker of different indicator lights, buzzer, or comprise voice messaging of suggestion content etc., the present invention does not do concrete restriction to this.
Based on above-mentioned analysis, the embodiment of the present invention is by carrying out Real-Time Monitoring to the actual bus voltage of inverter bus, and calculate the first difference of this actual bus voltage and target busbar voltage, when determining that the absolute value of this first difference is greater than the first voltage threshold, utilize this first difference to calculate the bus current value of inductance element in inverter, afterwards, according to this target current value, regulate the current electric current of inductance element in this inverter, thereby make the absolute value of the difference between actual bus voltage and target bus be not more than the first voltage threshold, avoided making to be connected in parallel on the capacitance damage on inversion bus because of the overtension of inversion bus, solved in prior art because of the too high problem that reduces inversion conversion efficiency of inversion busbar voltage simultaneously.
As shown in Figure 4, be the schematic flow sheet of the another kind of control method of grid-connected inverter embodiment of the present invention,
In actual applications, once PV plate is started working, system will detector the actual PV voltage of output, as the description in above-described embodiment, when its output PV voltage is low pressure, be that actual PV voltage is while being less than target busbar voltage, will be by a DC/DC converter to its processing of boosting, until it is greater than target inversion busbar voltage, the voltage-stabilizing system of the voltage-stabilizing system of now inversion side and PV side will carry out voltage stabilizing processing simultaneously, wherein, the voltage stabilizing process of inversion side can be with reference to above-described embodiment, no longer describe in detail herein, and the voltage stabilizing process of PV side can be the following step of this enforcement, and when the PV of its output voltage is high pressure, be that actual PV voltage is while being greater than target busbar voltage, the one DC/DC converter is not worked, PV plate is directly inversion bussed supply by bypass mode, thereby make actual bus voltage be greater than target busbar voltage, now, the voltage-stabilizing system of inversion side also will carry out voltage stabilizing processing to inversion busbar voltage, the voltage stabilizing processing procedure of inversion side can be referring to above-described embodiment, no longer describe in detail herein, when by the default expectation of inversion busbar voltage voltage stabilizing value PV voltage, the voltage-stabilizing system of PV plate side also will carry out voltage stabilizing processing to its output PV voltage according to a DC/DC converter, concrete steps can comprise:
Step S401: the actual PV voltage of monitoring the PV plate output corresponding with inverter.
Wherein, in the present invention, once starting this step S401, system will carry out.
Step S402: this PV plate is carried out to MPPT scanning, determine the actual expectation PV voltage of this PV plate.
In the practical application of photovoltaic parallel in system, each PV plate has a corresponding DC/DC converter, be used for carrying out MPPT (Maximum Power Point Tracking, MPPT maximum power point tracking) scanning, by the voltage of this PV plate of disturbance, determine maximum power point, corresponding PV voltage is actual expectation PV voltage.
Step S403: the 3rd difference of the actual PV voltage that calculating monitors and this actual expectation PV voltage.
Step S404: whether the absolute value that judges the 3rd difference is greater than second voltage threshold value, if so, performs step S405, if not, returns to step S401.
Wherein, second voltage threshold value can determine according to actual needs, and the invention process does not limit its concrete numerical value, and as when the voltage stabilizing of PV plate being controlled when strict, this second voltage threshold value can be zero.
Step S405: utilize the current electric current of inductance element in the DC/DC converter that the 3rd difference adjustment is connected with this PV plate output, until the actual PV voltage monitoring is not more than described second voltage threshold value with the absolute value of the difference of actual expectation PV voltage.
Concrete, in the situation that the absolute value of the 3rd difference is greater than second voltage threshold value, when actual PV voltage is greater than actual expectation PV voltage, controlling the current electric current of inductance element in a DC/DC converter increases, otherwise, when actual PV voltage is less than actual expectation PV voltage, the current electric current of controlling inductance element in a DC/DC converter reduces, to reach the object of stablizing PV voltage.
As another embodiment of the present invention, the control method that the embodiment of the present invention provides is also applicable to the control structure shown in Fig. 3, now, except above steps, can also comprise:
Detect the grid-connected power of bearing power and inverter, and judge whether this grid-connected power is greater than bearing power, if so, utilize the 2nd DC/DC converter being connected with inversion bus to charge to energy-storage battery.If when this grid-connected power is less than bearing power, energy-storage battery Bat will discharge, wherein, the detailed process discharging and recharging of this energy-storage battery Bat can be referring to the corresponding part of above-described embodiment, and the present invention no longer repeats at this.
Preferably, energy-storage battery is charged or energy-storage battery discharge process in, can also monitor the physical holding of the stock capacity of this energy-storage battery, when this physical holding of the stock capacity reaches the maximum storage capacity of this energy-storage battery, this energy-storage battery is stopped to charging; When physical holding of the stock capacity reaches the minimum storage volume of energy-storage battery, control this energy-storage battery and stop electric discharge.
As can be seen here, in order further to guarantee the stable of inversion busbar voltage, the present embodiment is by monitoring the actual PV voltage of PV plate output, and when the absolute value of judging the tertiary voltage difference between itself and actual expectation PV voltage is greater than second voltage threshold value, by adjusting the current electric current of inductance element in the DC/DC converter being connected with this PV plate output, thereby make the PV voltage of PV plate output and the absolute value of the difference of actual expectation PV voltage be not more than second voltage threshold value.
As shown in Figure 5, structured flowchart for a kind of combining inverter control system of the present invention embodiment, this system can comprise: PV plate 501, input is connected with PV plate 501 outputs, output is connected with inverter 502 inputs, has and boosts with buck functionality and PV plate is carried out to MPPT scanning, determines a DC/DC converter 503 of the actual expectation PV voltage of described PV plate, be connected in parallel on the storage capacitor C of these inverter 502 inputs, these inverter 502 outputs are connected in parallel on electrical network.
Wherein, the one DC/DC converter 503 is for boosting or step-down processing to the PV voltage of PV plate output, and maximal power tracing, concrete, when PV plate output be low pressure time, the one DC/DC converter 503 is to its processing of boosting, otherwise, when PV plate output be high pressure time, a DC/DC converter 503 carries out step-down processing to it, carry out MPPT scanning, to determine the actual expectation PV voltage of this PV plate simultaneously.
It should be noted that, the concrete structure of a DC/DC converter 503 belongs to general knowledge known in this field, and the present invention is not described in detail in this.
In addition, also comprise with storage capacitor C two ends and being connected, the first monitoring device 504 of the actual bus voltage of monitoring inverter bus.In the present embodiment practical application, this first monitoring device 504 can comprise voltage sensor or instrument transformer etc.
Be connected with inverter 502 with this first monitoring device 504, receive the actual bus voltage of these the first monitoring device 504 outputs, and calculate the first difference between this actual bus voltage and target busbar voltage, when judging the absolute value of described the first difference and be greater than the first voltage threshold, utilize described the first difference to calculate the target current value of inductance element in described inverter, afterwards, according to this target current value, regulate the current electric current of inductance element in inverter 502, until the absolute value of the difference between the actual bus voltage monitoring and described target busbar voltage is not more than the first control device 505 of the first voltage threshold.
Wherein, this first control device 505 can comprise a plurality of controllers, in the present embodiment, and using controller 1 ring controller in this inversion side, utilize the electric current of the inductance element in 1 pair of inverter of this controller to control, to realize the adjustment to inversion busbar voltage; Using controller 2 ring controller outside this inversion side, utilize the capacity cell in 2 pairs of inverters of controller to control, so that the difference of inversion busbar voltage and target inversion busbar voltage is not more than the first voltage threshold, controller 2 is the outer ring controller of this inversion side.
As another embodiment of the present invention, this system can also comprise:
Be connected the second monitoring device of the actual PV voltage of monitoring PV plate 501 outputs with PV plate 501 outputs.
Wherein, this second monitoring device can be voltage sensor or instrument transformer etc.
Be connected with a DC/DC converter 503 with the second monitoring device, calculate the 3rd difference of actual PV voltage with the actual expectation PV voltage of the second monitoring device transmission, when determining that the absolute value of the 3rd difference is greater than second voltage threshold value, utilize the 3rd difference to adjust the current electric current of inductance element in a DC/DC converter 503, until the absolute value of the difference of the actual PV voltage monitoring and described actual expectation PV voltage is not more than the second control device of second voltage threshold value.
In the present embodiment, this second control device can comprise a plurality of controllers, concrete, using controller 3 as interior ring controller, controller 4 is as outer ring controller, when judging the absolute value of above-mentioned the 3rd difference and be greater than second voltage threshold value, utilize the preset algorithm in controller 4 to obtain expecting inductive current, afterwards, utilize this controller 3 to control the electric current of inductance element in a DC/DC converter 503, make it reach this expectation inductive current, thereby realize the control to PV voltage.
Preferably, this combining inverter control system can also comprise warning device, for when the system failure (as phenomenons such as overvoltage and/or overcurrents) being detected, and output alarm information.Concrete, this warning device can be buzzer, voice module or indicator light etc., do not do concrete restriction to this present invention.
As can be seen here, the embodiment of the present invention detects the actual bus voltage of inversion bus by the first monitoring device, and send to first control device, when the absolute value of judging the first difference between this actual bus voltage and target busbar voltage when this first control device is greater than the first voltage threshold, utilize this first difference to calculate inductance element target current value in inverter, according to this target current value, adjust afterwards the current electric current of inductance element in this inverter, so that the absolute value of the difference of the actual bus voltage monitoring and described target busbar voltage is not more than the first voltage threshold, thereby avoided making to be connected in parallel on the storage capacitor damage on inversion bus because of the overtension of inversion bus, solved in prior art because of the too high problem that reduces inversion conversion efficiency of inversion busbar voltage simultaneously.
As shown in Figure 6, be the structured flowchart of the another kind of combining inverter control system of the present invention embodiment, this system can comprise: PV plate 601; Input is connected with PV plate 601 outputs, and output is connected with inverter 602 inputs, has and boosts with buck functionality and PV plate is carried out to MPPT scanning, determines a DC/DC converter 603 of the actual expectation PV voltage of described PV plate; Be connected in parallel on the storage capacitor C of these inverter 602 inputs; One end is connected with inverter 602 inputs, has the 2nd DC/DC converter 604 boosting with buck functionality; The energy-storage battery 605 being connected with the other end of the 2nd DC/DC converter 604.
Wherein, when electrical network charges to energy-storage battery 605, the 2nd DC/DC converter 604 is for inversion busbar voltage is carried out to step-down processing, as 350V becomes 48V; When this energy-storage battery 606 discharges to electrical network, the 2nd DC/DC converter 604 is for processing that inversion busbar voltage is boosted, because inversion busbar voltage is stabilized in the required minimum voltage of inversion, thereby reduced the transformation ratio of the 2nd DC/DC converter, and then expanded the parts selection scope of the 2nd DC/DC converter, improved system effectiveness simultaneously.
Preferably, the two-way DC/DC converter that the 2nd DC/DC converter 604 can boost for two-stage or the two-way DC/DC converter of isolated form full-bridge transformer device structure, to reach the object of high step-up ratio.
In addition, can also comprise with storage capacitor C two ends and being connected, the first monitoring device 606 of the actual bus voltage of monitoring inverter bus.
Wherein, this first monitoring device 606 can comprise voltage sensor or instrument transformer etc.
Be connected with inverter 602 with this first monitoring device 606, receive the actual bus voltage of these the first monitoring device 606 outputs, and calculate the first difference between this actual bus voltage and target busbar voltage, when the absolute value of this first difference is greater than the first voltage threshold, utilize this first difference to calculate after the target current value of inductance element in inverter, according to this target current value, regulate the current electric current of inductance element in inverter 602, until the absolute value of the difference of the actual bus voltage monitoring and described target busbar voltage is not more than the first control device 607 of the first voltage threshold.
As the record of above-described embodiment, this first control device 607 can comprise two controllers.
Be connected the second monitoring device 608 of the actual PV voltage of monitoring PV plate 601 outputs with PV plate 601 outputs.
Wherein, this second monitoring device 608 can comprise voltage sensor or instrument transformer etc.
Be connected with a DC/DC converter 603 with the second monitoring device 608, calculate the 3rd difference of actual PV voltage with the actual expectation PV voltage of the second monitoring device 608 transmissions, and when the absolute value of the 3rd difference is greater than second voltage threshold value, utilize the 3rd difference to adjust the current electric current of inductance element in a DC/DC converter 603, until the actual PV voltage monitoring expects that with actual the difference of PV voltage is not more than the second control device 609 of second voltage threshold value.
In the present embodiment, this second control device 609 can comprise two controllers, and concrete control procedure can be referring to above-described embodiment corresponding part, and the present embodiment is not described in detail in this.
Be connected with energy-storage battery 605 outputs, monitor the 3rd monitoring device 610 of the tank voltage of this energy-storage battery 605, in the present embodiment, the 3rd monitoring device 610 can be voltage sensor.
Preferably, system can also comprise the display unit being connected with the 3rd monitoring device 610, for showing the current tank voltage of this energy-storage battery 605.
The 3rd control device 611 being connected with the 2nd DC/DC converter 604, in the present embodiment, the 3rd control device 611 can comprise a plurality of controllers, using controller 5 ring controller in battery side, controller 6 is as the outer ring controller of battery side, when energy-storage battery 605 electric discharge, without considering outer voltage, only need utilize the electric current of the inductance element in 5 pairs of the 2nd DC/DC converters 604 of controller to adjust, when the current storage volume that this energy-storage battery 605 detected when the 3rd monitoring device 610 reaches its minimum storage volume, control this energy-storage battery 605 and stop electric discharge.
And when this energy-storage battery is charged, can utilize controller 5 and controller 6 actings in conjunction, when the current storage volume that this energy-storage battery 606 detected when the 3rd monitoring device 611 reaches maximum storage capacity, control this energy-storage battery 605 and stop charging.Wherein, controller 6 is for controlling energy-storage battery voltage.
Preferably, this combining inverter control system can also comprise the warning device being connected with first control device 607 and/or second control device 609 and/or the 3rd control device 611, when there is overvoltage and/or overcurrent in definite system, and output alarm information.
Concrete, this warning device can be buzzer, voice module or indicator light etc., do not do concrete restriction to this present invention.
Preferably, the related controller of the above embodiment of the present invention can be PI controller.
Known based on above-mentioned analysis, it is stable that the embodiment of the present invention is controlled inversion busbar voltage by first control device, second control device is controlled the PV voltage stabilization of PV plate output, thereby meeting under the prerequisite of the required minimum busbar voltage of inversion, PV plate is carried out to maximal power tracing, by the 3rd control device, control energy-storage battery and discharge and recharge, realize the object to PV plate energy storage, simultaneously when inverter power is too low, supplemental capacity in time.
It should be noted that, in the various embodiments described above of the present invention, except above-mentioned recorded device, can also comprise for connecting link of each device etc., the present invention will not enumerate at this, so long as not those skilled in the art, pay that creative work determines, all belong to technical solution of the present invention.
In addition, for including operation or the entities such as " first " " second " in the various embodiments described above, it is only used for distinguishing these operations or entity, does not have each other orbution, is only in order more clearly to understand technical solution of the present invention.
In this specification, each embodiment adopts the mode of going forward one by one to describe, and each embodiment stresses is the difference with other embodiment, between each embodiment identical similar part mutually referring to.For the disclosed system of embodiment, because it corresponds to the method disclosed in Example, so description is fairly simple, relevant part partly illustrates referring to method.
Above-mentioned explanation to the disclosed embodiments, makes professional and technical personnel in the field can realize or use the present invention.To the multiple modification of these embodiment, will be apparent for those skilled in the art, General Principle as defined herein can, in the situation that not departing from the spirit or scope of the present invention, realize in other embodiments.Therefore, the present invention will can not be restricted to these embodiment shown in this article, but will meet the widest scope consistent with principle disclosed herein and features of novelty.
Claims (10)
1. a control method of grid-connected inverter, is characterized in that, described method comprises:
The actual bus voltage of monitoring inverter bus;
Calculate the first difference between described actual bus voltage and target busbar voltage, described target busbar voltage is the minimum voltage that meets described inverter success inversion;
Whether the absolute value that judges described the first difference is greater than the first voltage threshold;
If so, utilize described the first difference to calculate the target current value of inductance element in described inverter;
According to described target current value, regulate the current electric current of inductance element in described inverter until the absolute value of the difference between the actual bus voltage monitoring and described target busbar voltage is not more than described the first voltage threshold.
2. according to the method described in 1, it is characterized in that, the current electric current of the inductance element in the described inverter of described adjusting comprises:
When described actual bus voltage is greater than described target busbar voltage, increase the current electric current of inductance element in described inverter;
When described actual bus voltage is less than described target busbar voltage, reduce the current electric current of inductance element in described inverter.
3. method according to claim 2, is characterized in that, before the actual bus voltage of monitoring inverter bus, described method also comprises:
Monitor the actual PV voltage of the PV plate output corresponding with described inverter;
Calculate the second difference between described actual PV voltage and default target busbar voltage.
4. method according to claim 3, is characterized in that, be greater than zero and be greater than described the first voltage threshold, and when described actual bus voltage reaches default expectation PV voltage, described method also comprises when judging described the second difference:
Described PV plate is carried out to MPPT scanning, determine the actual expectation PV voltage of described PV plate;
The 3rd difference of the current actual PV voltage of the described PV plate that calculating detects and described actual expectation PV voltage;
Whether the absolute value that judges described the 3rd difference is greater than second voltage threshold value;
If, utilize the current electric current of inductance element in the DC/DC converter that described the 3rd difference adjustment is connected with described PV plate output, until the absolute value of the difference of the actual PV voltage detecting and described actual expectation PV voltage is not more than described second voltage threshold value.
5. method according to claim 3, it is characterized in that, when judge described the second difference be less than zero and absolute value be greater than described the first voltage threshold, and the absolute value that makes described the first difference by described actual PV boost in voltage is processed is while being not more than described the first voltage threshold, described method also comprises:
Described PV plate is carried out to MPPT scanning, determine the actual expectation PV voltage of described PV plate;
The 4th difference of the current actual PV voltage of the described PV plate that calculating detects and described actual expectation PV voltage;
Whether the absolute value that judges described the 4th difference is greater than tertiary voltage threshold value;
If, utilize the current electric current of inductance element in the DC/DC converter that described the 4th difference adjustment is connected with described PV plate output, until the absolute value of the difference of the actual PV voltage detecting and described actual expectation PV voltage is not more than described tertiary voltage threshold value.
6. according to the method described in claim 1-5 any one, it is characterized in that, described method also comprises:
Detect the grid-connected power of bearing power and described inverter;
When judging described grid-connected power and be greater than described bearing power, described actual bus voltage is depressurized to the specified charging voltage of energy-storage battery, be delivered to energy-storage battery;
When judging described grid-connected power and be less than described bearing power, the boost in voltage of energy-storage battery output, to described target busbar voltage, is delivered to described inverter.
7. method according to claim 6, is characterized in that, described energy-storage battery is charged or described energy-storage battery discharge process in, described method also comprises:
Monitor the physical holding of the stock capacity of described energy-storage battery;
When described actual energy storage is deposited capacity and reached the maximum storage capacity of described energy-storage battery, described energy-storage battery is stopped to charging;
When described physical holding of the stock capacity reaches the minimum storage volume of described energy-storage battery, control described energy-storage battery and stop electric discharge.
8. a combining inverter control system, described system comprises PV plate and the storage capacitor that is connected in parallel on inverter input terminal, it is characterized in that, described system also comprises:
Input is connected with PV plate output, and output is connected with described inverter input terminal, has and boosts and buck functionality, and described PV plate is carried out to MPPT scanning, determines a DC/DC converter of the actual expectation PV voltage of described PV plate;
Be connected the first monitoring device of the actual bus voltage of monitoring inverter bus with described storage capacitor two ends;
Be connected with described inverter with described the first monitoring device, receive the described actual bus voltage of this first monitoring device output, and calculate the first difference between described actual bus voltage and target busbar voltage, when judging the absolute value of described the first difference and be greater than the first voltage threshold, utilize this first difference to calculate the target current value of inductance element in described inverter, and the described target current value of foundation regulates the current electric current of inductance element in described inverter, until the absolute difference between the actual bus voltage monitoring and described target busbar voltage is not more than the first control device of described the first voltage threshold,
Wherein, described target busbar voltage is the minimum voltage that meets described inverter success inversion.
9. system according to claim 8, is characterized in that, described system also comprises:
Be connected with described PV plate output, monitor the second monitoring device of the actual PV voltage of described PV plate output;
Be connected with a described DC/DC converter with described the second monitoring device, calculate the 3rd difference of actual PV voltage with the actual expectation PV voltage of the second monitoring device transmission, when judging the absolute value of described the 3rd difference and be greater than second voltage threshold value, utilize described the 3rd difference to adjust the current electric current of inductance element in a described DC/DC converter, until the absolute value of the difference of the actual PV voltage monitoring and described actual expectation PV voltage is not more than the second control device of described second voltage threshold value.
10. system according to claim 9, is characterized in that, described system also comprises:
One end is connected with described inverter input terminal, has the 2nd DC/DC converter boosting with buck functionality;
The energy-storage battery being connected with the other end of described the 2nd DC/DC converter.
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