CN110277793A - A kind of two-stage type photovoltaic DC-to-AC converter active power balance control method - Google Patents
A kind of two-stage type photovoltaic DC-to-AC converter active power balance control method Download PDFInfo
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- CN110277793A CN110277793A CN201810219882.9A CN201810219882A CN110277793A CN 110277793 A CN110277793 A CN 110277793A CN 201810219882 A CN201810219882 A CN 201810219882A CN 110277793 A CN110277793 A CN 110277793A
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- H02J3/383—
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
- H02J3/388—Islanding, i.e. disconnection of local power supply from the network
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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
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- 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
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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
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
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Abstract
The present invention provides a kind of two-stage type photovoltaic DC-to-AC converter active power balance control method, using photovoltaic array, the voltage of DC/DC converter and output filter, current sample, the balance control of photovoltaic DC-to-AC converter active power is realized based on voltage control type inverter power self-balancing control strategy by upper layer.Control method of the present invention, which can reduce photovoltaic power generation, enhances support and balanced capacity of the photovoltaic power generation to isolated island micro-capacitance sensor to the dependence of conventional Power Generation Mode and energy storage device, and control algolithm regulation speed is fast.
Description
Technical field
The present invention relates to photovoltaic DC-to-AC converter technical fields, and in particular to a kind of two-stage type photovoltaic DC-to-AC converter active power balance
Control method.
Background technique
Sustainable, environmental-friendly photovoltaic power generation technology is constantly subjected to extensive concern, is plateau, island with can be convenient
Electric energy is provided Deng remote districts, avoids long distance power transmission.However, when only forming isolated island type micro-capacitance sensor with photovoltaic power generation technology,
Due to the support and balanced action of shortage bulk power grid, continue to be difficult to meet network and workload demand using Traditional control mode, and
And large-scale energy storage device, become the indispensable component part of photovoltaic micro, pole using devices such as the generators of fossil fuel
The earth limits photovoltaic power generation in the application of isolated island micro-capacitance sensor.
Inventors have found that the photovoltaic DC-to-AC converter in existing isolated island micro-capacitance sensor works under current control mode or voltage control
Under molding formula.In the previous case, that is, when using current control mode, photovoltaic DC-to-AC converter works under master/slave mode, as
Slave, in a manner of controlled current source tracking photovoltaic array maximum power point, network voltage is by main inverter or energy storage, generator
Equal devices maintain to stablize, and photovoltaic DC-to-AC converter output power is restricted by the environmental condition of solar power generation.In latter situation
Under, that is, when using voltage mode control, photovoltaic DC-to-AC converter can use constant voltage constant frequency or sagging equal control strategies, at this time inverter
DC side must have the energy storage devices such as battery support, micro-capacitance sensor busbar voltage by all light storage inverter maintain jointly, light
Photovoltaic array still works under maximal power tracing mode, and output power is determined by loading demand, and it is straight that inverter height relies on it
The energy storage device of side is flowed to balance photovoltaic power generation with the difference between workload demand.
Summary of the invention
The technical problem to be solved by the present invention is to provide a kind of two-stage for the drawbacks described above in the presence of the prior art
Formula photovoltaic DC-to-AC converter active power balance control method, can reduce photovoltaic power generation to conventional Power Generation Mode and energy storage device according to
Lai Xing enhances support and balanced capacity of the photovoltaic power generation to isolated island micro-capacitance sensor, and control algolithm regulation speed is fast.
Solving technical solution used by present invention problem is:
The present invention provides a kind of two-stage type photovoltaic DC-to-AC converter active power balance control method, the two-stage type photovoltaic inversion
Device includes at least one photovoltaic inversion unit, wherein each photovoltaic inversion unit includes sequentially connected photovoltaic array, DC/DC
Converter, inverter and output filter are connected in parallel between each photovoltaic inversion unit, and are supplied by ac bus to load
Electricity, for each photovoltaic inversion unit, the control method includes the following steps:
Measure the three-phase voltage sequential value u of inverter outputoutWith three-phase current sequential value iout, make uoutAnd ioutIt passes through respectively
Low-pass filter is crossed, respective filtered component of voltage u is obtainedoutfWith current component ioutf, recycle uoutfAnd ioutfIt calculates inverse
Become the active-power P of device reality outputoutfAnd reactive power Qoutf；
Measure the port voltage u of photovoltaic arraypvElectric current i is exported with photovoltaic arraypv, the two is multiplied to obtain photovoltaic array
Output power Ppv；
Measure DC side voltage of converter udc；
By Poutf、PpvAnd udcIt is updated to based in voltage control type inverter power self-balancing control strategy, obtains inversion
The voltage angular frequency of device reality outputp, recycle ωpThe voltage-phase θ of inverter reality output is obtained to time integralp；
By QoutfIt is updated in sagging control strategy, obtains the voltage magnitude U of inverter reality outputp；
uoutfAnd ioutfWith θpFor rotating coordinate system, is converted respectively by abc/dq, obtain the d shaft voltage u of inverterdout、
Q shaft voltage uqout, d shaft current idoutWith q shaft current iqout, U is setpU is instructed for the voltage d axis of inverterdp, setting 0 is inversion
The voltage q axis of device instructs uqp；
Make udout、idoutAnd udpAnd uqout、iqoutAnd uqpRespectively simultaneously by the Double closed-loop of voltage and current of inverter
Two groups of control results are obtained, by this two groups of control results with θpIt for rotating coordinate system, is converted by dq/abc, obtains PWM modulation
Signal simultaneously carries out PWM modulation, to obtain the switching signal for controlling inverter switching device network.
Optionally, described by Poutf、PpvAnd udcIt is updated to based on voltage control type inverter power self-balancing control strategy
In, obtain the voltage angular frequency of inverter reality outputpSpecifically:
Default DC side voltage of converter instruction value udc *With contravarianter voltage angular frequency reference value ωp *；
By udcWith udc *Make it is poor, the difference of the two is adjusted by pi regulator, pi regulator export adjusted result according to
Secondary and PpvAnd PoutfIt is poor to make, and makees the difference that difference obtains twice in succession and is adjusted by proportional controller, proportional controller output
Adjusted result and ωp *It is poor to make, and obtained difference is ωp。
Optionally, described by QoutfIt is updated in sagging control strategy, obtains the voltage magnitude U of inverter reality outputpTool
Body are as follows:
Obtain the voltage magnitude instruction value u of inverterref；
Make QoutfIt is adjusted by proportional controller, the adjusted result and u of proportional controller outputrefIt is poor to make, and obtains
Difference is Up。
Optionally, described to make udout、idoutAnd udpAnd uqout、iqoutAnd uqpIt is double by the voltage and current of inverter respectively
Closed-loop control simultaneously obtains two groups of control results specifically:
By udoutWith udpIt is poor to make, and the difference of the two carries out voltage adjusting by pi regulator, then by idoutWith the voltage
It is poor that adjusted result is made, and obtained difference carries out current regulation using pi regulator, to obtain one group of control result；
By uqoutWith uqpIt is poor to make, and the difference of the two carries out voltage adjusting by pi regulator, then by iqoutWith the voltage
It is poor that adjusted result is made, and obtained difference carries out current regulation using pi regulator, to obtain another group of control result.
Optionally, the control method further includes following steps:
By ωpPhotovoltaic operating point is updated to voluntarily in adaptation strategies, obtains photovoltaic array port voltage instruction value upvref；
Make upvrefBy the Double closed-loop of voltage and current of DC/DC converter, obtains PWM modulation signal and carry out PWM tune
System, so that the switching signal for controlling DC/DC converter is obtained, to change the port voltage u of photovoltaic arraypv, make its approach
In upvref。
Optionally, described by ωpPhotovoltaic operating point is updated to voluntarily in adaptation strategies, photovoltaic array port voltage is obtained and refers to
Enable value upvrefSpecifically:
The voltage angle frequency instruction value ω of default inverterref；
By ωpWith ωrefIt is poor to make, and the difference of the two is adjusted by pi regulator, obtains photovoltaic array output voltage
Preliminary instruction makes the preliminary instruction carry out amplitude limiting processing by limiter, obtains upvref。
Optionally, described that the preliminary instruction is made to carry out amplitude limiting processing by limiter, obtain upvrefSpecifically:
Calculate the port voltage difference of variation front and back photovoltaic array and the product (u of output power differencepv1-upv)×(ppv1-
ppv), wherein upvPhotovoltaic array port voltage before indicating variation, upv1Photovoltaic array port voltage after indicating variation, ppvTable
Photovoltaic array output power before showing variation, ppv1Photovoltaic array output power after indicating variation；
The product is judged whether less than zero, if so, being then current u by the preliminary instruction clippingpv；If not, continuing to adopt
Sample, until the product is less than zero.
Optionally, described to make upvrefBy the Double closed-loop of voltage and current of DC/DC converter, PWM modulation signal is obtained
Specifically:
By upvrefWith upvIt is poor to make, and the difference of the two carries out voltage adjusting by pi regulator, then by ipvWith the voltage tune
It is poor that nodule fruit makees, and obtained difference carries out current regulation using pi regulator, to obtain PWM modulation signal.
Optionally, for the photovoltaic operating point voluntarily adaptation strategies, seek to be adapted to from arbitrary initial operating point, normal shape
The maximum power operating point of photovoltaic array is not needed to determine under state, and photovoltaic array work is only maintained under the limiting condition of load heavy duty
Maximum power point.
The utility model has the advantages that
Two-stage type photovoltaic DC-to-AC converter active power balance control method of the present invention by adopting the above-described technical solution,
When being supported without other energy or large capacity energy storage, if total load consumption is less than all photovoltaic generation powers, can keep
Photovoltaic generating system stable operation；It is controlled without maximal power tracing, photovoltaic array can voluntarily be sought to be adapted to work at present demand
Operating point；Inverter can work under voltage mode control mode when its DC side is supported without large capacity energy storage.
Detailed description of the invention
Fig. 1 is two-stage type photovoltaic DC-to-AC converter main circuit topological structure schematic diagram provided in an embodiment of the present invention；
Fig. 2 is general plotting schematic diagram used in the embodiment of the present invention；
Fig. 3 is inverter control schematic illustration provided in an embodiment of the present invention；
Fig. 4 is DC/DC convertor controls schematic illustration provided in an embodiment of the present invention；
Fig. 5 is that the power of two photovoltaic inversion units provided in an embodiment of the present invention is illustrated with the simulation waveform of load variations
Figure；
Fig. 6 be photovoltaic array 1A provided in an embodiment of the present invention voltage and power with load variations schematic diagram；
Fig. 7 be photovoltaic array 1B provided in an embodiment of the present invention voltage and power with load variations schematic diagram.
In figure: 1,1A, 1B- photovoltaic array；2,2A, 2B-DC/DC converter；3,3A, 3B- inverter；4,4A, 4B-
Output filter；5- load；6- ac bus.
Specific embodiment
Technical solution in order to enable those skilled in the art to better understand the present invention, with reference to the accompanying drawings and examples to this
Invention is described in further detail.
Based on inventor discovery existing isolated island micro-capacitance sensor in photovoltaic DC-to-AC converter work under current control mode or
The problems of under voltage mode control, the present embodiment provides a kind of two-stage type photovoltaic DC-to-AC converter active powers to balance controlling party
Method, control algolithm regulation speed is fast, reduces photovoltaic power generation to the dependence of conventional Power Generation Mode and energy storage device, enhances
Support and balanced capacity of the photovoltaic power generation to isolated island micro-capacitance sensor.
Wherein, two-stage type photovoltaic DC-to-AC converter includes at least one photovoltaic inversion unit (alternatively referred to as photovoltaic DC-to-AC converter),
In each photovoltaic inversion unit include sequentially connected photovoltaic array, DC/DC converter, inverter and output filter, i.e.,
It is made of the cascade of photovoltaic array, DC/DC converter, inverter and output filter, is connected in parallel between each photovoltaic inversion unit,
And it is powered by ac bus to load.In the present embodiment, output filter uses LCL filter.
By taking two photovoltaic inversion units composition isolated island micro-capacitance sensors are powered to load as an example, as shown in Figure 1, one of photovoltaic
Inversion unit includes sequentially connected photovoltaic array 1A, DC/DC converter 2A, inverter 3A and output filter 4A, another
Photovoltaic inversion unit includes sequentially connected photovoltaic array 1B, DC/DC converter 2B, inverter 3B and output filter 4B, this
Two photovoltaic inversion units are connected in parallel, and are powered by ac bus 6 to load 5.
For each photovoltaic inversion unit, the control method includes the following steps S101 to S107.
S101. the three-phase voltage sequential value u of measurement inverter outputoutWith three-phase current sequential value iout, make uoutAnd iout
Pass through low-pass filter respectively, obtains respective filtered component of voltage uoutfWith current component ioutf, recycle uoutfAnd ioutf
Calculate the active-power P of inverter reality outputoutfAnd reactive power Qoutf。
Due to active-power PoutfAnd reactive power QoutfCalculating belong to the common knowledge of this field, so about Poutf
And QoutfSpecific calculating process repeat no more.
S102. the port voltage u of photovoltaic array is measuredpvElectric current i is exported with photovoltaic arraypv, the two is multiplied to obtain photovoltaic
Array output power Ppv。
S103. DC side voltage of converter u is measureddc。
S104. by Poutf、PpvAnd udcIt is updated to based in voltage control type inverter power self-balancing control strategy, obtains
The voltage angular frequency of inverter reality outputp, recycle ωpThe voltage-phase of inverter reality output is obtained to time integral
θp。
The step S104 is specifically included:
S104-1. DC side voltage of converter instruction value u is presetdc *With contravarianter voltage angular frequency reference value ωp *；
S104-2. as shown in figure 3, by udcWith udc *It is poor (even if u to makedc *Subtract udc), the difference of the two passes through pi regulator
Be adjusted, pi regulator output adjusted result successively with PpvAnd PoutfWork is poor (first to make PpvSubtract pi regulator output
Adjusted result obtains a difference, then makes PoutfSubtract the difference), make the difference that difference obtains twice in succession and passes through proportional controller
It is adjusted, the adjusted result of proportional controller output is the voltage angular frequency deviation instruction value Δ ω of inverterp, by Δ ωpWith
ωp *It is poor (even if ω to makep *Subtract Δ ωp), obtained difference is ωp；
S104-3. as shown in figure 3, utilizing ωpThe voltage-phase θ of inverter reality output is obtained to time integralp。
S105. by QoutfIt is updated in sagging control strategy, obtains the voltage magnitude U of inverter reality outputp。
The step S105 is specifically included:
S105-1. the voltage magnitude instruction value u of inverter is obtainedref；
S105-2. as shown in figure 3, making QoutfIt is adjusted by proportional controller, the adjusting knot of proportional controller output
Fruit and urefIt is poor (even if u to makerefSubtract the adjusted result of proportional controller output), obtained difference is Up。
S106.uoutfAnd ioutfWith θpFor rotating coordinate system, is converted respectively by abc/dq, obtain the d shaft voltage of inverter
udout, q shaft voltage uqout, d shaft current idoutWith q shaft current iqout, U is setpU is instructed for the voltage d axis of inverterdp, setting 0
U is instructed for the voltage q axis of inverterqp。
S107. make udout、idoutAnd udpAnd uqout、iqoutAnd uqpPass through the voltage and current double closed-loop control of inverter respectively
Two groups of control results are made and obtain, by this two groups of control results with θpIt for rotating coordinate system, is converted by dq/abc, obtains PWM
Modulated signal simultaneously carries out PWM modulation, to obtain the switching signal for controlling inverter switching device network.
The step S107 is specifically included:
S107-1. as shown in figure 3, by udoutWith udpIt is poor (even if u to makedpSubtract udout), the difference of the two is adjusted by PI
Device carries out voltage adjusting, then by idoutIt is poor (even if the voltage adjusted result subtracts i to make with the voltage adjusted resultdout), it obtains
Difference using pi regulator carry out current regulation, to obtain one group of control result；
S107-2. as shown in figure 3, by uqoutWith uqpIt is poor (even if u to makeqpSubtract uqout), the difference of the two is adjusted by PI
Device carries out voltage adjusting, then by iqoutIt is poor (even if the voltage adjusted result subtracts i to make with the voltage adjusted resultqout), it obtains
Difference using pi regulator carry out current regulation, to obtain another group of control result；
S107-3. as shown in figure 3, by this two groups of control results with θpFor rotating coordinate system, converted respectively by dq/abc,
Obtain PWM modulation signal；
S107-4. PWM modulation is carried out using the PWM modulation signal that step S107-3 is obtained, to obtain inverse for controlling
Become the switching signal of device switching network.
Inventor also found, for the DC/DC converter of two-stage type photovoltaic DC-to-AC converter DC terminal, the port of photovoltaic array
There are two types of voltages and power control mode.The first control mode uses maximal power tracing strategy, controls photovoltaic port voltage
Always the maximum power point for tracking photovoltaic array under the environmental condition makes it maintain work near maximum power point in stable state
Make；Second of control mode still uses maximal power tracing technology, is with the difference of the first control mode, photovoltaic battle array
It can work in maximum power point when column stable state, however when load reduces or intensity of illumination increases, operating point can be with maximum
Power points is accordingly corrected, to reduce the power output of photovoltaic array.As it can be seen that both the above control mode is all be unable to do without to photovoltaic battle array
Column carry out maximal power tracing, increase the complexity of control, greatly reduce the speed of response, thus to the orphan of photovoltaic power generation
Island application causes biggish limitation.
To solve the above problems, control method described in the present embodiment further includes following steps S108 and S109.
S108. by ωpPhotovoltaic operating point is updated to voluntarily in adaptation strategies, obtains photovoltaic array port voltage instruction value
upvref。
The step S108 is specifically included:
S108-1. the voltage angle frequency instruction value ω of inverter is presetref；
S108-2. as shown in figure 4, by ωpWith ωrefIt is poor (even if ω to makerefSubtract ωp), the difference of the two is adjusted by PI
Device is adjusted, and obtains the preliminary instruction of photovoltaic array output voltage, and the preliminary instruction is made to carry out amplitude limiting processing by limiter,
Obtain upvref。
In step S108-2, as shown in figure 4, the preliminary instruction is made to carry out amplitude limiting processing by limiter, u is obtainedpvref
Specifically:
Calculate the port voltage difference of variation front and back photovoltaic array and the product (u of output power differencepv1-upv)×(ppv1-
ppv), wherein upvPhotovoltaic array port voltage before indicating variation, upv1Photovoltaic array port voltage after indicating variation, ppvTable
Photovoltaic array output power before showing variation, ppv1Photovoltaic array output power after indicating variation；
The product is judged whether less than zero, if so, being then current u by the preliminary instruction clippingpv, i.e., with current upvFor
Instruction, no longer change photovoltaic array port voltage；If not, continuing to sample, until the product is less than zero.
In the present embodiment, for the photovoltaic operating point voluntarily adaptation strategies, seek to be adapted to from arbitrary initial operating point, just
The maximum power operating point that photovoltaic array is not needed to determine under normal state, only maintains photovoltaic array under the limiting condition of load heavy duty
Work maximum power point.
S109. make upvrefBy the Double closed-loop of voltage and current of DC/DC converter, obtains PWM modulation signal and carry out
PWM modulation, so that the switching signal for controlling DC/DC converter is obtained, to change the port voltage u of photovoltaic arraypv, control
It is to upvrefVariation, even if it levels off to upvref。
The step S109 is specifically included:
S109-1. as shown in figure 4, by upvrefWith upvIt is poor (even if u to makepvSubtract upvref), the difference of the two is adjusted by PI
Device carries out voltage adjusting, then by ipvIt is poor (even if the voltage adjusted result subtracts i to make with the voltage adjusted resultpv), it obtains
Difference carries out current regulation using pi regulator, to obtain PWM modulation signal；
S109-2. PWM modulation is carried out using the PWM modulation signal that step S109-1 is obtained, to obtain for controlling DC/
The switching signal of DC converter, to change the port voltage u of photovoltaic arraypv, it is made to level off to upvref。
It should be noted that the sequence of above-mentioned steps is simply to illustrate that the present embodiment and a specific example proposing,
Without limitation to the sequences of above-mentioned steps, those skilled in the art can on demand be adjusted it present invention in practical applications.
For example, step S108 to step S109 can move to after step S104.
Fig. 2 is general plotting schematic diagram used in the embodiment of the present invention.As shown in Fig. 2, the embodiment of the present invention utilizes photovoltaic
Array, the voltage of DC/DC converter and output filter, current sample, by upper layer based on voltage control type inverter function
Rate self-balancing control strategy and photovoltaic operating point voluntarily both algorithms of adaptation strategies, it is flat to realize photovoltaic DC-to-AC converter active power
Weighing apparatus control.
Fig. 3 is inverter control schematic illustration provided in an embodiment of the present invention.As shown in figure 3, the control of inverter
Journey is divided into three parts, and first part is by DC side voltage of converter instruction value udc *, DC side voltage of converter udc, photovoltaic battle array
Column output power Ppv, inverter reality output active-power Poutf, contravarianter voltage angular frequency reference value ωp *, DC side electricity
Pi regulator and active sagging coefficient composition are pressed, the voltage-phase θ of inverter reality output is obtainedp, active sagging system therein
Number constitutes active power and exports the linear sagging relationship between angular frequency；Second part is instructed by the voltage magnitude of inverter
Value uref, inverter reality output reactive power QoutfIt is constituted with idle sagging coefficient, obtains the voltage d axis instruction of inverter
udpU is instructed with q axisqp, idle sagging coefficient therein constitutes under linear between output reactive power and output voltage amplitude
The relationship of hanging down；Part III instructs u by the voltage d axis of inverterdpU is instructed with q axisqp, the d shaft voltage u of inverterdout, q shaft voltage
uqout, d shaft current idoutWith q shaft current iqoutAnd Voltage loop pi regulator and electric current loop pi regulator are constituted, and obtain two groups
Control result, by this two groups of control results with θpIt for rotating coordinate system, is converted by dq/abc, obtains PWM modulation signal and go forward side by side
Row PWM modulation, to obtain the switching signal for controlling inverter switching device network.
Fig. 4 is DC/DC convertor controls schematic illustration provided in an embodiment of the present invention.As shown in figure 4, by inverter reality
The voltage angular frequency of border outputpPhotovoltaic operating point is updated to voluntarily in adaptation strategies, obtains the instruction of photovoltaic array port voltage
Value upvref, then make upvrefBy the Double closed-loop of voltage and current of DC/DC converter, PWM modulation signal is obtained.Utilize the PWM
Modulated signal carries out PWM modulation, the switching signal for controlling DC/DC converter can be obtained, to change the port of photovoltaic array
Voltage upv, it is controlled to upvrefVariation, even if it levels off to upvref。
Fig. 5 is that the power of two photovoltaic inversion units provided in an embodiment of the present invention is illustrated with the simulation waveform of load variations
Figure.As shown in figure 5, emulated on main circuit topology shown in Fig. 1, wherein load in 1.5s off-load, load in 1.8s,
Inverter is using control method shown in Fig. 3.From fig. 5, it can be seen that the active power of output of inverter responds rapidly to, in 1.5s
It accordingly reduces with load off-load, is increase accordingly in 1.8s with load on, to realize adaptation load power variation
Purpose.
Fig. 6 be photovoltaic array 1A provided in an embodiment of the present invention voltage and power with load variations schematic diagram.Such as Fig. 6
Shown, DC/DC converter uses control method shown in Fig. 4, and for load when 1.5s off-load and 1.8s load, photovoltaic array 1A is logical
Itself operating point of the spontaneous adjustment of DC/DC converter is crossed, its port voltage is accordingly reduced or increased, to change the output work of photovoltaic
Rate adapts to the demand of inverter 3A and load.
Fig. 7 be photovoltaic array 1B provided in an embodiment of the present invention voltage and power with load variations schematic diagram.Such as Fig. 7
Shown, similar with photovoltaic array 1A, photovoltaic array 1B uses identical control method, load when 1.5s off-load and 1.8s are loaded,
Photovoltaic array 1B is adjusted by itself operating point of the spontaneous adjustment of DC/DC converter, its port voltage of DC/DC converter controlling changing
Whole output power adapts to the demand of inverter 3B and load.
In conclusion using photovoltaic array, DC/DC converter, inverter and the cascade system structure of output filter
Under, two-stage type photovoltaic DC-to-AC converter active power balance control method is in inverter direct-flow side without large capacity described in the embodiment of the present invention
Under conditions of energy storage support, ac bus are supported without other energy, is worked in a manner of controlled voltage source, maintenance light can be directly controlled
The port voltage and frequency stabilization of photovoltaic array, to facilitate ac bus voltage stabilization.At the same time, DC/DC converter without
Maximal power tracing need to be carried out, but photovoltaic array best operating point is voluntarily regulated and controled according to invertor operation mode, adjusts photovoltaic
The output power of array maintains source lotus power-balance.Moreover, the case where photovoltaic micro is supported without other energy or energy storage
Under, using control method described in the embodiment of the present invention, photovoltaic power generation can voluntarily active control microgrid energy be balanced, algorithm letter
Single feasible, tracking velocity is fast, and response characteristic is good.
It is understood that the principle that embodiment of above is intended to be merely illustrative of the present and the exemplary implementation that uses
Mode, however the present invention is not limited thereto.For those skilled in the art, essence of the invention is not being departed from
In the case where mind and essence, various changes and modifications can be made therein, these variations and modifications are also considered as protection scope of the present invention.
Claims (9)
1. a kind of two-stage type photovoltaic DC-to-AC converter active power balance control method, the two-stage type photovoltaic DC-to-AC converter includes at least one
A photovoltaic inversion unit, wherein each photovoltaic inversion unit includes sequentially connected photovoltaic array, DC/DC converter, inversion
Device and output filter are connected in parallel between each photovoltaic inversion unit, and are powered by ac bus to load, and feature exists
In for each photovoltaic inversion unit, the control method includes the following steps:
Measure the three-phase voltage sequential value u of inverter outputoutWith three-phase current sequential value iout, make uoutAnd ioutRespectively through too low
Bandpass filter obtains respective filtered component of voltage uoutfWith current component ioutf, recycle uoutfAnd ioutfCalculate inverter
The active-power P of reality outputoutfAnd reactive power Qoutf；
Measure the port voltage u of photovoltaic arraypvElectric current i is exported with photovoltaic arraypv, the two is multiplied to obtain photovoltaic array output work
Rate Ppv；
Measure DC side voltage of converter udc；
By Poutf、PpvAnd udcIt is updated to based in voltage control type inverter power self-balancing control strategy, it is real to obtain inverter
The voltage angular frequency of border outputp, recycle ωpThe voltage-phase θ of inverter reality output is obtained to time integralp；
By QoutfIt is updated in sagging control strategy, obtains the voltage magnitude U of inverter reality outputp；
uoutfAnd ioutfWith θpFor rotating coordinate system, is converted respectively by abc/dq, obtain the d shaft voltage u of inverterdout, q axis electricity
Press uqout, d shaft current idoutWith q shaft current iqout, U is setpU is instructed for the voltage d axis of inverterdp, setting 0 is inverter
Voltage q axis instructs uqp；
Make udout、idoutAnd udpAnd uqout、iqoutAnd uqpPass through the Double closed-loop of voltage and current of inverter respectively and obtains
Two groups of control results, by this two groups of control results with θpIt for rotating coordinate system, is converted by dq/abc, obtains PWM modulation signal
And PWM modulation is carried out, to obtain the switching signal for controlling inverter switching device network.
2. control method according to claim 1, which is characterized in that described by Poutf、PpvAnd udcIt is updated to based on voltage
In control type inverter power self-balancing control strategy, the voltage angular frequency of inverter reality output is obtainedpSpecifically:
Default DC side voltage of converter instruction value udc *With contravarianter voltage angular frequency reference value ωp *；
By udcWith udc *Make it is poor, the difference of the two is adjusted by pi regulator, pi regulator export adjusted result successively with
PpvAnd PoutfIt is poor to make, and makees the difference that difference obtains twice in succession and is adjusted by proportional controller, the tune of proportional controller output
Nodule fruit and ωp *It is poor to make, and obtained difference is ωp。
3. control method according to claim 1, which is characterized in that described by QoutfIt is updated in sagging control strategy, obtains
To the voltage magnitude U of inverter reality outputpSpecifically:
Obtain the voltage magnitude instruction value u of inverterref；
Make QoutfIt is adjusted by proportional controller, the adjusted result and u of proportional controller outputrefMake poor, obtained difference
As Up。
4. control method according to claim 1, which is characterized in that described to make udout、idoutAnd udpAnd uqout、iqout
And uqpThe Double closed-loop of voltage and current Jing Guo inverter and obtain two groups of control results respectively specifically:
By udoutWith udpIt is poor to make, and the difference of the two carries out voltage adjusting by pi regulator, then by idoutIt adjusts and ties with the voltage
It is poor that fruit makees, and obtained difference carries out current regulation using pi regulator, to obtain one group of control result；
By uqoutWith uqpIt is poor to make, and the difference of the two carries out voltage adjusting by pi regulator, then by iqoutIt adjusts and ties with the voltage
It is poor that fruit makees, and obtained difference carries out current regulation using pi regulator, to obtain another group of control result.
5. control method described in any one of -4 according to claim 1, which is characterized in that the control method further includes as follows
Step:
By ωpPhotovoltaic operating point is updated to voluntarily in adaptation strategies, obtains photovoltaic array port voltage instruction value upvref；
Make upvrefBy the Double closed-loop of voltage and current of DC/DC converter, obtains PWM modulation signal and carry out PWM modulation, from
And the switching signal for controlling DC/DC converter is obtained, to change the port voltage u of photovoltaic arraypv, it is made to level off to
upvref。
6. control method according to claim 5, which is characterized in that described by ωpPhotovoltaic operating point is updated to voluntarily to be adapted to
In strategy, photovoltaic array port voltage instruction value u is obtainedpvrefSpecifically:
The voltage angle frequency instruction value ω of default inverterref；
By ωpWith ωrefIt is poor to make, and the difference of the two is adjusted by pi regulator, obtains the preliminary of photovoltaic array output voltage
Instruction makes the preliminary instruction carry out amplitude limiting processing by limiter, obtains upvref。
7. control method according to claim 6, which is characterized in that described to limit the preliminary instruction by limiter
Width processing, obtains upvrefSpecifically:
Calculate the port voltage difference of variation front and back photovoltaic array and the product (u of output power differencepv1-upv)×(ppv1-ppv),
Wherein upvPhotovoltaic array port voltage before indicating variation, upv1Photovoltaic array port voltage after indicating variation, ppvIt indicates to become
Photovoltaic array output power before change, ppv1Photovoltaic array output power after indicating variation；
The product is judged whether less than zero, if so, being then current u by the preliminary instruction clippingpv；If not, continuing to sample, directly
Until the product is less than zero.
8. control method according to claim 5, which is characterized in that described to make upvrefBy the voltage of DC/DC converter
Current double closed-loop control, obtains PWM modulation signal specifically:
By upvrefWith upvIt is poor to make, and the difference of the two carries out voltage adjusting by pi regulator, then by ipvIt adjusts and ties with the voltage
It is poor that fruit makees, and obtained difference carries out current regulation using pi regulator, to obtain PWM modulation signal.
9. control method according to claim 5, which is characterized in that for the photovoltaic operating point voluntarily adaptation strategies,
Seek to be adapted to from arbitrary initial operating point, the maximum power operating point of photovoltaic array is not needed to determine under normal condition, only in load
Photovoltaic array work maximum power point is maintained under the limiting condition of heavy duty.
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