CN108988379A - Based on the grid-connected varying index novel Integration Reset Control strategy method of photovoltaic multi-electrical level inverter - Google Patents
Based on the grid-connected varying index novel Integration Reset Control strategy method of photovoltaic multi-electrical level inverter Download PDFInfo
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- H02J3/385—
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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
- H02J3/24—Arrangements for preventing or reducing oscillations of power in networks
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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
- H02J3/46—Controlling of the sharing of output between the generators, converters, or transformers
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- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
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Abstract
The varying index novel Integration Reset Control strategy method grid-connected based on photovoltaic multi-electrical level inverter that the invention discloses a kind of, the control method include: the photo-voltaic power supply output voltage and inverter direct-flow side input current for measuring each concatenation unit of DC side；By optimal power point tracing, the reference voltage of inverter direct-flow side is calculated；By voltage and current double -loop control, the amplitude of sinusoidal modulation wave is calculated；It measures network voltage and electric current and the frequency and phase angle of modulating wave is calculated by phaselocked loop；Introduce index r and L, wherein L=1, r ∈ N+Or L=2, r=2, the r power of sinusoidal modulation wave is calculated, sinusoidal r power modulating wave is denoted as；Sinusoidal modulation wave r-L power is calculated, is integrated and is resetted, be denoted as class sawtooth wave；Modulating wave and carrier wave are compared, square wave of the generation pulsewidth close to sinusoidal variations；Phase shift generates multichannel and has square wave of the dephased pulsewidth close to sinusoidal variations；According to circuit operating condition, r and L is adjusted, obtains a variety of common simplification integral reset methods.
Description
Technical field
The present invention relates to mobile communication technology fields.Refer to more particularly to a kind of change grid-connected based on photovoltaic multi-electrical level inverter
Number integral reset control method (Variable Exponent Integrate Reset Control, VEIRC).
Background technique
There are many kinds of inverter control methods, and in nonlinear control method, integral reset method is very common one kind, usually
Situation is controlled using integral reset device.
Traditional integral reset device includes integrator, comparator and S-R trigger.The R of S-R trigger (Reset resets)
End is connect with an output end of comparator, and the output end of integrator and another input terminal of comparator connect, S-R trigger
Output end and the reset terminal of integrator connect, the end output Q of trigger and selection switch connection select the output of switch to be used for
Control inverter switch device being opened and turning off.
It is different according to the input of comparator, different control methods can be divided.Now be more widely single-revolution
Control (One Cycle Control, OCC) and energy balance control (Energy Balance Control, EBC).Comparator
It is the comparison of two signals, for OCC, one of input signal is grid side reference voltage, this signal is to pass through
The sine wave being calculated；Another signal is the signal that DC voltage source output voltage is obtained by integral.EBC is come
It says, one of input signal is the product of grid side reference voltage and grid side reference current, and voltage reference value is to pass through meter
The sine wave obtained, since ideally, voltage and current is in phase, i.e., power factor is 1, therefore current reference
Value is the sine wave with voltage reference value with same phase but different amplitudes frequently；Another signal is DC side electric power output voltage
With the integral of amp product, the energy being lost along with double sampling spaced filters.
Although the dynamic property of OCC and EBC to a certain extent can be than traditional sinusoidal pulse width modulation (Sinusoidal
Pulse Width Modulation, SPWM) it to get well, but a voltage sensor more than OCC ratio SPWM, and EBC ratio SPWM
More a voltage sensor and a current sensors.For photovoltaic multi-electrical level inverter grid-connected system as shown in Figure 1, using
Switching tube --- the more level cascading topological structures of diode, then every level-one requires a controller, therefore its controller and biography
The use of sensor can increase with the increase of more level series.
When uneven part shading occurs for photo-voltaic power supply, such as wherein some unit shades, other units are just
Often when work, since OCC and EBC introduces the voltage and current at diode both ends, it can be allowed when calculating originally due to hiding
The unit aggravation voltage decline that yin causes voltage to decline, and acceleration system is collapsed.
Traditional quadrature restorer needs clock pulses to be triggered, and trigger pulse duty ratio is smaller, and system is more stable, ripple
It is smaller.However the trigger pulse of hardware circuit is to need certain pulsewidth that can just be triggered.
Summary of the invention
The purpose of the present invention is to solve drawbacks described above in the prior art, provide a kind of based on photovoltaic multi-level inverse conversion
It the characteristics of grid-connected varying index novel Integration Reset Control strategy method of device, this method is according to topological structure, can be run according to system difference
Situation, fast and easy are adjusted, to ensure the stable operation of system.
The purpose of the present invention can be reached by adopting the following technical scheme that:
A kind of varying index novel Integration Reset Control strategy method grid-connected based on photovoltaic multi-electrical level inverter, the integral reset control
Preparation method includes the following steps:
S1, the photo-voltaic power supply output voltage v for acquiring each concatenation unitpvnWith output electric current ipvn；
S2, pass through optimal power point tracing, calculate the reference voltage of inverter direct-flow side
S3, pass through voltage and current double -loop control, calculate the amplitude of sinusoidal modulation wave；
S4, acquisition network voltage vgridWith electric current igrid；
S5, the phase angle and frequency that sinusoidal modulation wave is calculated by phaselocked loop；
S6, according to amplitude, phase angle and frequency, synthesize sinusoidal modulation wave；
S7, the r power for calculating sine wave are denoted as sinusoidal r power modulating wave, wherein r ∈ N as new modulating wave+；
S8, the r-L power for calculating sine wave synthesize approximate sawtooth wave, are denoted as class sawtooth by integrating and resetting calculating
Wave, wherein r >=L, L=1,2；
S9, modulating wave and carrier wave are compared, square wave of the generation pulsewidth close to sinusoidal variations；
S10, phase shift generate multichannel and have square wave of the dephased pulsewidth close to sinusoidal variations；
S11, according to circuit operating condition, adjust r and L, obtain a variety of common simplification integral reset methods.Wherein, work as r=
It is Cycle Control method when 1, L=1, works as r=2, when L=1 is energy balance control methods, works as r=2, and when L=2 is zero impedance control
Method.
Further, the step S2 is specifically included:
S201, when photo-voltaic power supply is in normal illumination, according to MPPT maximum power point tracking algorithm search maximum power point；
S202, when photo-voltaic power supply be in balance part shading when, the optimizing in the voltage range of permission；
S203, when photo-voltaic power supply be in it is unbalanced part shading when, it may be assumed that a certain concatenation unit shades, other grades
Receipts or other documents in duplicate member illumination is normal, and optimal power point tracker will calculate a minimum voltage value at this time, and system will be in this minimum
Operation.
Further, the step S7 is specifically included:
S701, sine table is established, current sinusoidal value is obtained by look-up table；
S702, the frequency that sine wave is modified by changing scan frequency；
S703, according to different r values, establish sine r times table.
Further, the step S8 is specifically included:
S801, the r-L power for calculating sine wave, and carry out integral reset operation.Known L=1, r ∈ N+Or L=2, r=
2, it as r-L=0, is actually integrated to 1, then resetted within the specific time, operation output waveform is just at this time
It is standard sawtooth wave.It is then that sinusoidal r power is integrated and resetted, output waveform is class sawtooth wave as r-L ≠ 0.
S802, it resets using period forcing reset；
S803, according to different r values, calculate sine r-L power；
S804, it is determined according to switching frequency in a cycle of sine r power, the class sawtooth wave quantity of positive half cycle.In order to
Ensure that the peak value of modulating wave is not lost, it is general to choose odd number class sawtooth wave；
S805, since each class sawtooth wave got according to sinusoidal r-L exponential integral, the shape of each
It is different.According to the number of class sawtooth wave, the table of integrals of respective numbers is established, current integration value is obtained by look-up table.
Further, the step S11 is specifically included:
S1101, according to circuit operating condition, select suitable r and L value.Under normal conditions, r=1, L=1 are selected
It meets the requirements.When circuit needs harmonic wave to become smaller, L=1 can be enabled, increases r value.Filter inductance discharge band when needing to eliminate commutation
The due to voltage spikes come, can enable r=2, L=2.
S1102, when uneven part shading occurs for photo-voltaic power supply, system dc side will operate in minimum voltage value, such as
It is improper that this voltage value of fruit is chosen, and will lead to the unstable of system transition.System can be made to stablize by adjusting r and L value
It crosses.Meanwhile this is also that the minimum voltage value selection of optimal power point tracker expands range.
The present invention has the following advantages and effects with respect to the prior art:
(1) the invention proposes varying index novel Integration Reset Control strategy method VEIRC, have under the topological structure and only one
PWM controller, it is only necessary to can have dephased PWM wave by output multi-channel simultaneously by software control.
(2) this control methods combines a variety of common integral reset methods, and proposes zero impedance control methods, filters out electric current
Filter inductance electric discharge causes the due to voltage spikes of inverter when commutation.The index of VEIRC can be adjusted according to running situation
R is switched fast suitable integral reset method, to reach better control effect.
Detailed description of the invention
Fig. 1 is real topology and control algolithm schematic diagram of the invention, is research with the topological structure of 4 concatenation units
Object；
Fig. 2 is double -loop control schematic diagram；
Fig. 3 is PWM generating principle figure of the invention；
Fig. 4 be modulating wave and carrier wave [0, pi/2) ideal waveform in the period；
Fig. 5, which show power network current waveform, has level-one when unbalanced part shading occurs for the photo-voltaic power supply of this system
Receipts or other documents in duplicate member is shaded, and when other concatenation units work normally, the setting of OPPT output reference voltage is inappropriate, can be passed through
VEIRC regulation coefficient r makes system stablize transition, power network current wave when Fig. 5 (a), Fig. 5 (b), Fig. 5 (c) are r=1,2,3 respectively
Shape；
Fig. 6 show inverter output voltage, is the output voltage of inverter under common algorithm control shown in Fig. 6 (a)；
Fig. 6 (b) is shown under VEIRC control, the output voltage of inverter；
Fig. 7 is the stream of the varying index novel Integration Reset Control strategy method grid-connected based on photovoltaic multi-electrical level inverter disclosed by the invention
Cheng Tu.
Specific embodiment
In order to make the object, technical scheme and advantages of the embodiment of the invention clearer, below in conjunction with the embodiment of the present invention
In attached drawing, technical scheme in the embodiment of the invention is clearly and completely described, it is clear that described embodiment is
A part of the embodiment of the present invention, instead of all the embodiments.Based on the embodiments of the present invention, those of ordinary skill in the art
Every other embodiment obtained without making creative work, shall fall within the protection scope of the present invention.
Embodiment
VEIRC is simply introduced below.
VEIRC, i.e. varying index novel Integration Reset Control strategy method (Variable Exponent Integrate Reset
Control,VEIRC).It is compared with traditional integral reset method, the method reduce sampling elements, and combine a variety of integrals
Repositioning can switch over by adjusting index, calculate simply, applicability is wider.
As shown in Figure 1, this topological structure is a kind of switching tube --- diode cascade multilevel inverter, by forward and backward
Grade converter is in series, and the front stage converter is by N number of switching tube --- and diode cascade is constituted, specially full-control type
Electronic power switch S1nType diode D is not controlled1nIt is connected in series.
The rear class converter is single-phase full bridge inverter circuit, is specially made of 4 full-control type power electronic switches
Single-phase full bridge inverter circuit, by full-control type power electronic switch S21、S23Series connection obtains bridge arm 1, S22、S24Be connected in series bridge arm
2, the output of inverter is connected with five rank RLC filters.
In the present embodiment, N selection 4, i.e. concatenation unit number are 4.In each concatenation unit, photo-voltaic power supply is by three
The photovoltaic panel of block model Trina Solar TSM-250PA05.08 is connected in series.Filter is five rank LC filters, right
The topological structure of title can realize the two-way flow of energy.Electrical network parameter is 110V, 60Hz, connects two loads 1 and 2.
Entire control flow includes: the photo-voltaic power supply output voltage and inverter direct current for measuring each concatenation unit of DC side
Side input current；By optimal power point tracing (Optimum Power Point Tracking, OPPT), inversion is calculated
The reference voltage of device DC side；By voltage and current double -loop control, the amplitude of sinusoidal modulation wave is calculated；Measure network voltage and
Electric current calculates the frequency and phase angle of modulating wave by phaselocked loop；Introduce index r and L, wherein L=1, r ∈ N+Or L=2, r=
2, the r power of sinusoidal modulation wave is calculated, sinusoidal r power modulating wave is denoted as；Calculate sinusoidal modulation wave r-L power, carry out integral and
It resets, is denoted as class sawtooth wave；Modulating wave and carrier wave are compared, square wave of the generation pulsewidth close to sinusoidal variations；Phase shift generates
Multichannel has square wave of the dephased pulsewidth close to sinusoidal variations；According to circuit operating condition, r and L is adjusted, is obtained a variety of common
Simplification integral reset method.
Using VEIRC control technology, the control pulse of front stage converter successively misplaces Ts/ N time, wherein TsFor switch week
Phase.For concatenation unit 1, the clock pulses phase shift of one-cycle controller is set as 0, VEIRC and is sent into switch S11Switching signal be g1；
For concatenation unit 2, the clock pulses phase shift of one-cycle controller is set as Ts/ 4, VEIRC are sent into switch S12Switching signal be g2；
For concatenation unit n, the clock pulses phase shift of one-cycle controller is set as (n-1) Ts/ N, VEIRC are sent into switch S1nSwitching signal
For gn.In the present embodiment, N=4 is taken.
The control of rear class inverter is by determining that the positive and negative of given voltage signal opens up and down to obtain the same bridge arm of inverter
The modulated signal of each switching tube of pipe complementation conducting is closed, wherein S21Switching signal be g21, S22Switching signal be g22, S23's
Switching signal is g23, S24Switching signal be g24.When given voltage signal is timing, switch S21S24It is connected and S22S23Shutdown,
Inverter output voltage v at this timeinvDirection and vdcIt is identical；When given voltage signal is negative, switch S22S23It is connected and S21S24
It turns off, at this time inverter output voltage vinvDirection and vdcOn the contrary.It is positive and negative that output voltage is realized by the alternate conduction of switch
The alternating of half cycle.
Wherein, the process of OPPT control is as shown in Fig. 7, comprising the following steps:
S1, the photo-voltaic power supply output voltage v for acquiring each concatenation unitpvnWith output electric current ipvn；
S2, pass through optimal power point tracing, calculate the reference voltage of inverter direct-flow side
Step S2 process is as follows:
S201, when photo-voltaic power supply is in normal illumination, according to MPPT maximum power point tracking algorithm search maximum power point；
S202, when photo-voltaic power supply be in balance part shading when, the optimizing in the voltage range of permission；
S203, when photo-voltaic power supply be in it is unbalanced part shading when, it may be assumed that a certain concatenation unit shades, other grades
Receipts or other documents in duplicate member illumination is normal, and optimal power point tracker will calculate a minimum voltage value at this time, and system will be in this minimum
Operation.
S3, pass through voltage and current double -loop control, calculate the amplitude of sinusoidal modulation wave；
As shown in Fig. 2, being voltage and current double -loop control schematic diagram.
Calculate the photo-voltaic power supply output voltage of each concatenation unitWith the calculated reference value of OPPTIt compares.
Fiducial value is changed by mark, i.e., divided by a reference valuePI calculating is carried out, here it is outer voltage adjustings.The value again with power grid
Electric current i after dq is decomposeddIt makes comparisons, carries out PI calculating, here it is current inner loop adjustings.It calculates resulting value and power grid passes through
Cross the voltage v after dq is decomposeddIt makes comparisons, as decomposition value of the inverter ac side voltage reference value in d axisAt this point, considering
The influence of filter is added feedforward link and carries out electric current correction, introduces the equivalent inductance ω L of filter respectively1With ω L2。
Similarly, for idle, the photo-voltaic power supply output for calculating each concatenation unit is idleAnd and reference valueMake
Compare.Fiducial value is changed by mark, i.e., divided by a reference valueSince photo-voltaic power supply is provided only with function power, the calculating
The result is that 0.PI calculating is then carried out, here it is outer voltage adjustings.The value electric current i with power grid after dq is decomposed againqMake
Compare, carries out PI calculating, here it is current inner loop adjustings.Calculate the voltage v of resulting value and power grid after dq is decomposedqMake ratio
Compared with as decomposition value of the inverter ac side voltage reference value in q axisAt this point, considering the influence of filter, feed-forward loop is added
Section carries out electric current correction, introduces the equivalent inductance ω L of filter respectively1With ω L2。
Resulting inverter ac side voltage reference value is calculated again divided by measured valueMultiplied by the benchmark of network voltage
ValueUsing the conversion of real part imaginary part/amplitude phase angle, i.e., tentatively obtain required modulation wave amplitude and phase angle.
S4, acquisition network voltage vgridWith electric current igrid；
S5, the phase angle and frequency that sinusoidal modulation wave is calculated by phaselocked loop；
As shown in Fig. 2, after tentatively obtaining required modulation wave amplitude and phase angle, it is contemplated that the switch time of switching tube,
Phase angle compensation is carried out, 2 π f are addednormTs, wherein fnormIt is mains frequency, TsIt is the switch periods of switching tube.
S6, according to amplitude, phase angle and frequency, synthesize sinusoidal modulation wave；
S7, the r power for calculating sine wave are denoted as sinusoidal r power modulating wave, wherein r ∈ N as new modulating wave+；
Step S7 process is as follows:
S701, sine table is established, current sinusoidal value is obtained by look-up table；
S702, the frequency that sine wave is modified by changing scan frequency；
S703, according to different r values, establish sinusoidal sine r times table；
S8, the r-L power for calculating sine wave synthesize approximate sawtooth wave, are denoted as class sawtooth by integrating and resetting calculating
Wave, wherein r >=L, L=1,2；
Step S8 process is as follows:
S801, the r-L power for calculating sine wave, and carry out integral reset operation.Known L=1, r ∈ N+Or L=2, r=
2, it as r-L=0, is actually integrated to 1, then resetted within the specific time, operation output waveform is just at this time
It is standard sawtooth wave.It is then that sinusoidal r power is integrated and resetted, output waveform is class sawtooth wave as r-L ≠ 0.
S802, it resets using period forcing reset；
S803, according to different r values, calculate sine r-L power；
S804, it is determined according to switching frequency in a cycle of sine r power, the class sawtooth wave quantity of positive half cycle.In order to
Ensure that the peak value of modulating wave is not lost, it is general to choose odd number class sawtooth wave；
S805, since each class sawtooth wave got according to sinusoidal r-L exponential integral, the shape of each
It is different.According to the number of class sawtooth wave, the table of integrals of respective numbers is established, current integration value is obtained by look-up table.
Traditional integral reset method resets integral term using S-R trigger, shown in control principle such as Fig. 3 (a).
By emulation it is found that the clock pulses duty ratio for being used to startup trigger work is smaller, the ripple of system is smaller, and system is also more steady
It is fixed.But the trigger pulse of actual hardware circuit is to be unable to reach minimum duty ratio.Therefore the present embodiment uses look-up table
Replace and calculate in real time, content of tabling look-up is updated by timer.Shown in its control principle such as Fig. 3 (b).
Assuming that one end input of comparator isThe other end inputsWherein TsFor the switch periods of switching tube.Change r value is conducive to photo-voltaic power supply and exists
Occur still to be able to be transitioned into another stable state from a stable state stabilization when shading of part.
The selectable range of r and L is limited, and range of choice can be by establishing F (x, r, L)=f*(x,r)-h*(x,
R, L) it determines.Enable f*(x, r)=sinr(x),And x ∈ [0, π).According to f*(x, r) and h*
(x, r, L) function limit, it is recognised that x ∈ [0, π) on, two functions must have intersection point.In order to guarantee in the section
It is interior, have in addition to origin and only one intersection point, enablesMeet in the section in addition to origin again without intersection point.
F (x)=0 is enabled, is solved: as L=1, r ∈ [1 ,+∞) when, F (x)=0 exists at this timeOn have and only
One solution, i.e. origin；As L=2, when r=2, only there is a solution on origin.At this point, meeting the value of condition
Range are as follows: as L=1, r ∈ [1 ,+∞), r ∈ N+；The r=2 as L=2.
Ensure x ∈ [0, π) in addition to origin one and only one intersection point, be to guarantee that the on-off of switching tube will not be because
Cause to repeat to cut-off for function itself monotonicity, and then causes system unstable.
As shown in figure 4, solid line indicates f*(x, r)=sinr(x) in r from 1 change to 5 when function variation；Dotted line indicatesMiddle r-L changes to the 4 function variations for being from 0.As it can be seen that when uneven part shading occurs,
System fails to run according to the minimum voltage value that OPPT is set or the setting of OPPT minimum voltage is inappropriate, then can pass through liter
High r value, reduces power network current slowly, finally stable to be transitioned into new stable state.In other words, the selection of r value can be in photovoltaic panel
When part shading occurs, the range of choice of OPPT minimum voltage is allowed to expand.
As shown in figure 5, the minimum voltage of the output of OPPT randomly selects when uneven part shading occurs for photo-voltaic power supply
Value in one allowed band, shown in power network current such as Fig. 5 (a).Index r is increased, operational effect improves, and waveform is more preferable, such as
Shown in Fig. 5 (b).Continue to increase index r, operational effect continues to improve, and wave distortion is smaller, can be from a state smooth transition
To another state.Continue to increase index r at this time, effect loses growth.It can be seen that r=3 is the best ginseng of the operating status at this time
Number.
S9, modulating wave and carrier wave are compared, square wave of the generation pulsewidth close to sinusoidal variations；
S10, phase shift generate multichannel and have square wave of the dephased pulsewidth close to sinusoidal variations；
Shown in traditional integral reset method such as Fig. 3 (a), if to generate multichannel has dephased PWM wave, just have to
There is the S-R trigger of the dephased clock pulses of the tool of equivalent amount and equivalent amount.But software control is used, lead to
The master slave mode for crossing the advanced timer of chip carries out phase shift, can fast generate the PWM wave met the requirements.
S11, according to circuit operating condition, adjust r and L, obtain a variety of common simplification integral reset methods.Wherein, work as r=
It is Cycle Control method when 1, L=1, works as r=2, when L=1 is energy balance control methods, works as r=2, and when L=2 is zero impedance control
Method.
Step S11 process is as follows:
S1101, according to circuit operating condition, select suitable r and L value.Under normal conditions, r=1, L=1 are selected
It meets the requirements.When circuit needs harmonic wave to become smaller, L=1 can be enabled, increases r value.Filter inductance discharge band when needing to eliminate commutation
The due to voltage spikes come, can enable r=2, L=2.
S1102, when uneven part shading occurs for photo-voltaic power supply, system dc side will operate in minimum voltage value, such as
It is improper that this voltage value of fruit is chosen, and will lead to the unstable of system transition.System can be made to stablize by adjusting r and L value
It crosses.Meanwhile this is also that the minimum voltage value selection of optimal power point tracker expands range.
Work as r=1, when L=1, this control algolithm be exactly simplified Cycle Control method (One Cycle Control,
OCC).One end input of the comparator of common OCC is through over-sampling and to calculate modified grid side voltage | vgrid|, the other end is defeated
Entering is a certain concatenation unit diode D of DC side1nBoth end voltage | v1n| integral.Remember that the input of OCC comparator both ends is F1(t)=
|vgrid| andGrid side voltage vgridIt is the sine wave of a standard of comparison, passes through MPPT and bicyclic control
After system is adjusted, the unit sine wave that an amplitude is not more than 1 is reformed intoTherefore | vgrid| can simplify forPass through
AdjustmentAmplitude so that adjust pulse width, so as to adjust the switch time of switching tube.Amplitude be also known as the index of modulation
m.For another input terminal of comparator, due to v1nActually in switching tube S1nMeasured value is v when conducting1n, in S1nIt is surveyed when shutdown
Magnitude is 0.It therefore can be v1nDivided by DC side photo-voltaic power supply output voltage, unit turns to 1.Therefore to v1nIntegral it is practical
Upper is exactly to add up to 1.I.e.Simplify an OCC electricity fewer than tradition OCC
Pressure sensor, and for more level topological structures, each concatenation unit just lacks a voltage sensor, altogether less n it is electric
Pressure sensor.
Work as r=2, when L=1, this control algolithm is exactly simplified energy balance control (Energy Balance
Control,EBC).One end input of the comparator of common EBC is through over-sampling and to calculate modified grid side energy.Assuming that electric
Net side is highly stable, then instantaneous power can represent the mean power in the very short time, then grid side instantaneous energy can be with table
It is shown asvgridAnd igridAll represent sampled value.Since filter has internal resistance, energy, and energy storage member can be consumed
For part in unstable state, the energy of the energy and release that store in a cycle is not necessarily equal, therefore the energy of filter
Also it counts.It is more to need to participate in the energy-storage travelling wave tube calculated for more complicated filter.Therefore the total input in this one end isWith Δ WLnIndicate the energy of filter consumption.The input of the comparator other end is a certain cascade of DC side
Cell diodes D1nBoth ends power v1n·i1nIntegral.Note EBC comparator both ends, which input, isWithGrid side voltage vgridBe a standard of comparison just
String wave, and grid side electric current igridIt is also the sine wave of a standard of comparison in stable state.Ideally, vgridAnd igridIt is
With frequency with phase.vgridAfter being adjusted by MPPT and double -loop control, unit of the amplitude no more than 1 is being turned to just with regard to unit
String waveigridIt can also be turned to unitTherefore | vgrid·igrid| can simplify forBy adjustingAmplitude into
And pulse width is adjusted, so as to adjust the switch time of switching tube.Amplitude, that is, index of modulation m be also one no more than 1
Positive number.For another input terminal of comparator, v1n1 can be turned to unit；For i1n, since topological structure shown in FIG. 1 limits
System, has | i1n|≈|idc|≈|igrid|, therefore can also be i1nIt is reduced toIt is right | v1n·i1n| integral be just reduced to pair
Integral.I.e.It is fewer by one than tradition EBC to simplify EBC
A voltage sensor and a current sensor, and for more level topological structures, each concatenation unit just lacks an electricity
Pressure sensor and a current sensor, have lacked altogether n voltage sensor and n current sensor.
Work as r=2, when L=2, proposes zero impedance control methods (Zero Impedance Control, ZIC).The comparison of ZIC
One end input of device is all grid side ideal instant power, and calculation method is through over-sampling and to calculate modified grid side voltage
Square divided by grid side impedance, i.e.,Wherein ZgridIndicate from LC filter side, that is, Fig. 1 in terms of the both ends CD to power grid etc.
Imitate impedance.The other end input of comparator is the ideal instant power that each concatenation unit is supplied to inverter ac side, meter
Calculation method isWherein ZinvIndicate from inverter side, that is, Fig. 1 in terms of the both ends AB to the equivalent impedance of power grid.Note ZIC compares
Device both ends inputWithSince there are internal resistance, Er Qieshi for practical filter
Perception, there is energy loss, and can release energy when electric current commutates, the output voltage of inverter is caused point occur
Peak.In order to solve this problem, it is assumed that filter impedance 0, i.e. ideal filter, at this time from AB toward grid side visit enter etc.
Effect impedance just as entered from CD toward grid side spy, that is, has Zgrid=Zinv.Therefore each moment enters from the spy of the both ends AB
Instantaneous power and to visit the instantaneous power entered from the both ends CD should be equal.One end of comparator can be with abbreviationSeparately
One end can be the integral to 1 with abbreviation.I.e.ZIC can not needed
Additional filter discharge loop causes contravarianter voltage spike when can reach its electric discharge of inhibition.Its function and effect such as Fig. 6 institute
Show, Fig. 6 (a) indicates the output voltage of inverter under general control algorithm, it can be noted that occurs due to voltage spikes at zero passage.Through
After crossing ZIC control, although staircase waveform is not very perfect, spike has been eliminated.Therefore can by control index r,
These types of integral reset method is used alternatingly according to the actual situation.
The above embodiment is a preferred embodiment of the present invention, but embodiments of the present invention are not by above-described embodiment
Limitation, other any changes, modifications, substitutions, combinations, simplifications made without departing from the spirit and principles of the present invention,
It should be equivalent substitute mode, be included within the scope of the present invention.
Claims (7)
1. a kind of varying index novel Integration Reset Control strategy method grid-connected based on photovoltaic multi-electrical level inverter, which is characterized in that described
Novel Integration Reset Control strategy method includes the following steps:
S1, the photo-voltaic power supply output voltage v for acquiring each concatenation unitpvnWith output electric current ipvn；
S2, pass through optimal power point tracing, calculate the reference voltage of inverter direct-flow side
S3, pass through voltage and current double -loop control, calculate the amplitude of sinusoidal modulation wave；
S4, acquisition network voltage vgridWith electric current igrid；
S5, the phase angle and frequency that sinusoidal modulation wave is calculated by phaselocked loop；
S6, according to amplitude, phase angle and frequency, synthesize sinusoidal modulation wave；
S7, the r power for calculating sine wave are denoted as sinusoidal r power modulating wave, wherein r ∈ N as new modulating wave+；
S8, the r-L power for calculating sine wave synthesize approximate sawtooth wave, are denoted as class sawtooth wave by integrating and reset calculating,
Wherein r >=L, L=1,2；
S9, modulating wave and carrier wave are compared, square wave of the generation pulsewidth close to sinusoidal variations；
S10, phase shift generate multichannel and have square wave of the dephased pulsewidth close to sinusoidal variations；
S11, according to circuit operating condition, adjust r and L, obtain and simplify integral reset method, wherein work as r=1, when L=1 is single-revolution
Control methods, work as r=2, and when L=1 is energy balance control methods, work as r=2, and when L=2 is zero impedance control methods.
2. the varying index novel Integration Reset Control strategy method grid-connected based on photovoltaic multi-electrical level inverter according to claim 1,
It is characterized in that, the step S2 process is as follows:
S201, when photo-voltaic power supply is in normal illumination, according to MPPT maximum power point tracking algorithm search maximum power point；
S202, when photo-voltaic power supply be in balance part shading when, the optimizing in the voltage range of permission；
S203, when photo-voltaic power supply be in it is unbalanced part shading when, it may be assumed that a certain concatenation unit shades, other grade of receipts or other documents in duplicate
First illumination is normal, and optimal power point tracker will calculate a minimum voltage value at this time, simultaneously based on photovoltaic multi-electrical level inverter
Net will be run in this minimum.
3. the varying index novel Integration Reset Control strategy method grid-connected based on photovoltaic multi-electrical level inverter according to claim 1,
It is characterized in that, the step S7 process is as follows:
S701, sine table is established, current sinusoidal value is obtained by look-up table；
S702, the frequency that sine wave is modified by changing scan frequency；
S703, according to different r values, establish sine r times table.
4. the varying index novel Integration Reset Control strategy method grid-connected based on photovoltaic multi-electrical level inverter according to claim 1,
It is characterized in that, the step S8 process is as follows:
S801, the r-L power for calculating sine wave, and carry out integral reset operation, it is known that L=1, r ∈ N+Or L=2, r=2, work as r-
It when L=0, integrating to 1, then is resetted within the specific time, operation output waveform is exactly standard sawtooth wave at this time, when
It is then that sinusoidal r power is integrated and resetted, output waveform is class sawtooth wave when r-L ≠ 0；
S802, it resets using period forcing reset；
S803, according to different r values, calculate sine r-L power；
S804, it is determined according to switching frequency in a cycle of sine r power, the class sawtooth wave quantity of positive half cycle；
S805, according to the number of class sawtooth wave, establish the table of integrals of respective numbers, pass through look-up table obtain current integration value.
5. the varying index novel Integration Reset Control strategy method grid-connected based on photovoltaic multi-electrical level inverter according to claim 1,
It is characterized in that, the step S11 process is as follows:
S1101, according to circuit operating condition, select suitable r and L value, it is generally the case that selection r=1, L=1 can meet
It is required that enabling L=1 when circuit needs harmonic wave to become smaller, r value is increased, filter inductance discharge band is come when circuit needs to eliminate commutation
Due to voltage spikes, enable r=2, L=2；
S1102, when uneven part shading occurs for photo-voltaic power supply, to be transported based on the grid-connected DC side of photovoltaic multi-electrical level inverter
Row is in minimum voltage value, by adjusting r and L value, makes based on the stability of grid connection transition of photovoltaic multi-electrical level inverter.
6. the varying index novel Integration Reset Control strategy method grid-connected based on photovoltaic multi-electrical level inverter according to claim 4,
It is characterized in that, in the step S804, chooses odd number class sawtooth wave and do not lost with the peak value for ensuring modulating wave.
7. the varying index novel Integration Reset Control strategy method grid-connected based on photovoltaic multi-electrical level inverter according to claim 4,
It is characterized in that, since each class sawtooth wave is got according to sinusoidal r-L exponential integral, the shape of each is different
Sample.
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| CN102738825A (en) * | 2012-06-11 | 2012-10-17 | 合肥工业大学 | Novel photovoltaic grid-connected system based on modularized multi-level converter |
| CN104953877A (en) * | 2015-07-21 | 2015-09-30 | 沈阳工业大学 | T-type three-level inverter finite set model prediction control method and system |
| CN205004985U (en) * | 2014-12-01 | 2016-01-27 | 合肥天舟光伏技术有限公司 | Photovoltaic grid power station |
| CN105932715A (en) * | 2016-06-28 | 2016-09-07 | 西南石油大学 | Method for determining position of suddenly-changed state of sliding mode controlled inverter |
| US20160380556A1 (en) * | 2015-06-26 | 2016-12-29 | Board Of Trustees Of Michigan State University | System and method for optimizing fundamental frequency modulation for a cascaded multilevel inverter |
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| CN102738825A (en) * | 2012-06-11 | 2012-10-17 | 合肥工业大学 | Novel photovoltaic grid-connected system based on modularized multi-level converter |
| CN205004985U (en) * | 2014-12-01 | 2016-01-27 | 合肥天舟光伏技术有限公司 | Photovoltaic grid power station |
| US20160380556A1 (en) * | 2015-06-26 | 2016-12-29 | Board Of Trustees Of Michigan State University | System and method for optimizing fundamental frequency modulation for a cascaded multilevel inverter |
| CN104953877A (en) * | 2015-07-21 | 2015-09-30 | 沈阳工业大学 | T-type three-level inverter finite set model prediction control method and system |
| CN105932715A (en) * | 2016-06-28 | 2016-09-07 | 西南石油大学 | Method for determining position of suddenly-changed state of sliding mode controlled inverter |
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