CN107342598B - A kind of isolated island micro-capacitance sensor harmonic power distribution method based on harmonic impedance control - Google Patents
A kind of isolated island micro-capacitance sensor harmonic power distribution method based on harmonic impedance control Download PDFInfo
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Classifications
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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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- 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
- H02J3/01—Arrangements for reducing harmonics or ripples
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- H02J3/382—
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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
- Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
- Y02E40/40—Arrangements for reducing harmonics
Abstract
The isolated island micro-capacitance sensor harmonic power distribution method based on harmonic impedance control that the invention discloses a kind of, the present invention have initially set up the sagging relationship between the impedance of DG Equivalent Harmonic and DG residual capacity, i.e. ZDGk_h_eq‑SDGk_remainingSagging relationship, according to the Equivalent Harmonic impedance of each DG of residual capacity differentiation of each DG.By ZDGk_h_eq‑SDGk_remainingSagging relationship and the harmonic impedance control method by detecting h three phase harmonic voltage of h three phase harmonic current control inverter reality output of inverter reality output in DG combine, and the actual Equivalent Harmonic impedance of DG is made to meet ZDGk_h_eq‑SDGk_remainingSagging relationship realizes the target of the residual capacity distribution harmonic power according to DG.Control algolithm of the invention is more succinct, and operand is smaller, and the DG Equivalent Harmonic impedance of design is also more reasonable.
Description
Technical field
The invention belongs to isolated island microgrid powers to distribute field, in particular to a kind of isolated island based on harmonic impedance control is micro-
Mains by harmonics power distribution method.
Background technique
With petering out for traditional fossil energy, the research and utilization of the renewable energy such as photovoltaic power generation, wind-power electricity generation
Increasingly it is valued by people.However, since renewable energy has the characteristics that dispersibility, fluctuation etc. are intrinsic, so can
The conversion and utilization of the renewable sources of energy are difficult to dissolve on a large scale by traditional power grid form.In order to solve this problem, micro-capacitance sensor
Concept is come into being.Micro-capacitance sensor is incorporated into the power networks to be known as with isolated operation two states, the micro-capacitance sensor in island operation state
Isolated island micro-capacitance sensor.As the interface network of renewable energy power generation and comprehensive utilization, utilization of the micro-capacitance sensor for renewable energy
Efficiency and quality have vital influence.Meanwhile as the useful supplement to traditional bulk power grid, micro-capacitance sensor is to electric power networks
Reliability and flexibility have be obviously improved effect.There is the above advantage in view of micro-capacitance sensor, in recent years by academia
The more and more extensive concern with industry.Many countries have carried out the further investigation to micro-capacitance sensor the relevant technologies in the world,
And set up micro-capacitance sensor laboratory and demonstration project that a batch has Important Academic meaning and application value.How to construct safety,
Reliably, efficient micro-grid system, and how sufficiently to excavate current transformer in micro-grid system and controlled in power transmission, power quality
The value of reason aspect has become the hot issue of research micro-capacitance sensor at present.
There are a large amount of power electronic equipment and non-linear, uncompensated load in isolated island micro-capacitance sensor, lead to its electric energy matter
Amount receives serious adverse effect.When not carrying out special control, the system parameter variations and distribution of isolated island micro-capacitance sensor
The traditional control method that inverter uses in generator unit (DG) can make the Equivalent Harmonic impedance of DG have biggish uncertainty
And irrationality, and then cause harmonic power distribution that there is biggish uncertain and irrationality, to be easy to cause certain
The overload of DG.
In existing document, for the harmonic power assignment problem in isolated island micro-capacitance sensor, there is researcher to propose a variety of sides
Method.A kind of method be by being constructed between harmonic wave active and reactive power and harmonic voltage frequency, amplitude respectively to each harmonic under
The relationship of hanging down realizes the target of distribution harmonic power.This method not only needs precise measurement each harmonic power, and controller is set
Meter is also very complicated, and operand is also bigger.Another method is to introduce virtual harmonic impedance by directly connecting, controllably difference
Change the Equivalent Harmonic impedance of each DG, and then realizes the target of distribution harmonic power.However, the existing virtual harmonic impedance of introducing
In method, the algorithm for calculating the virtual harmonic impedance introduced in each DG is complex, it is also desirable to each harmonic power into
Row precise measurement, while the expression formula of constructed virtual harmonic impedance will receive the influence of multiple variables, to make each DG's
Difference between Equivalent Harmonic impedance can not uniquely be determined by the difference between the residual capacity of each DG, cause it in distribution harmonic wave
There are certain irrationalities on power.
Summary of the invention
The object of the invention is that a kind of isolated island micro-capacitance sensor harmonic power distribution method based on harmonic impedance control is provided,
Under conditions of not needing communication system, the residual capacity according to DG is realized with relatively simple control algolithm and lesser operand
The target for distributing harmonic power can preferably overcome present in current existing isolated island micro-capacitance sensor harmonic power distribution method
Need the limitations such as precise measurement each harmonic power, control algolithm are complicated, the big and virtual harmonic impedance design of operand is unreasonable
Property.
In order to achieve the above objectives, the present invention adopts the following technical scheme:
A kind of isolated island micro-capacitance sensor harmonic power distribution method based on harmonic impedance control, comprising the following steps:
Step 1) measures the corresponding fundamental wave feed line impedance Z of k-th of DG in isolated island micro-capacitance sensor after each DG installationlk_f
With h subharmonic feed line impedance Zlk_h；
Step 2), measurement obtain the three-phase of inverter reality output in k-th of DG filtered after link by LC in DG
Electric current iDGkWith the three-phase voltage v of reality outputDGk, to iDGkAnd vDGkRespective fundametal compoment i is obtained after filteringDGk_fWith
vDGk_f, to iDGk_fAnd vDGk_fIt carries out abc/dq coordinate transform and obtains the dq component of inverter output fundamental current and fundamental voltage
IDGk_f_d、IDGk_f_q、VDGk_f_dAnd VDGk_f_q, and inverter exports in k-th of DG fundamental active power and fundamental wave is calculated
The actual value P of reactive powerDGk_fAnd QDGk_f；
Step 3), the fundamental active power that inverter in k-th of DG obtained in step 2) is exported and fundamental wave reactive power function
The actual value P of rateDGk_fAnd QDGk_fIt is updated in the sagging control strategy of fundamental wave, obtains the frequency of inverter output voltage in k-th of DG
Rate fDGkWith amplitude VDGk_f, by frequency fDGkPhase theta is obtained to time integral multiplied by 2 π and by result, is then enabled inverse in k-th of DG
Become the d shaft voltage component of device output as VDGk_f, and the q shaft voltage component for enabling it export is 0, is obtained by dq/abc coordinate transform
The reference value v for the fundamental voltage that inverter exports in k-th of DG under abc coordinate system* DGk_f；
Step 4), the fundamental active power and fundamental wave reactive power function of inverter output in k-th of the DG obtained according to step 2)
The actual value P of rateDGk_f、QDGk_fAnd the rated capacity S of k-th given of DGDGk_ratedThe residual capacity of k-th of DG is calculated
SDGk_remaining；
Step 5) establishes the sagging relationship between the h equivalent harmonic impedance of k-th of DG and its residual capacity, i.e.,
ZDGk_h_eq-SDGk_remainingSagging relationship, the residual capacity S for k-th of DG that step 4) is obtainedDGk_remainingIt substitutes into
ZDGk_h_eq-SDGk_remainingIn sagging relationship, the h equivalent harmonic impedance Z for k-th of DG that expectation is realized is obtainedDGk_h_eq；
Step 6), the Z that step 5) is obtainedDGk_h_eqSubtract the corresponding h subharmonic feeder line resistance of k-th of DG that step 1) obtains
Anti- Zlk_h, obtain h times that needs to introduce in k-th of DG virtual harmonic impedance Zvk_h；
Step 7) measures step 2) the three-phase current i of inverter reality output in k-th obtained of DGDGkIt is filtered
Wave obtains h three phase harmonic electric current i of its reality outputDGk_h, by iDGk_hThe Z obtained with step 6)vk_hIt is multiplied and then takes result
Opposite number, as in k-th of DG inverter export h subharmonic voltage reference value v* DGk_h；
Step 8), the reference value v of the fundamental voltage of inverter output in k-th of DG that step 3) is obtained* DGk_fWith step
7) the reference value v for the h subharmonic voltage that inverter exports in k-th of the DG obtained* DGk_hIt is added, considers main low-order harmonic,
That is h=5,7,11,13, then obtain the reference value v of inverter output voltage in k-th of DG* DGk, to v* DGkCarry out abc/ α β coordinate
Transformation, obtains v* DGkComponent v under α β coordinate system* DGk_αAnd v* DGk_β, reference as outer voltage；
Step 9) measures step 2) the three-phase voltage v of inverter reality output in k-th obtained of DGDGkCarry out abc/
α β coordinate transform, obtains vDGkComponent v under α β coordinate systemDGk_αAnd vDGk_β, v that step 8) is obtained* DGk_αAnd v* DGk_βPoint
V is not subtractedDGk_αAnd vDGk_β, acquired results are inputted respectively in PR controller, using the output result of PR controller as electricity
Flow the reference i of inner ring* Lfk_αAnd i* Lfk_β；
Step 10) obtains inverter side filter inductance L in k-th of DG by measurementfkOn electric current iLfk, to iLfkIt carries out
Abc/ α β coordinate transform, obtains iLfkComponent i under α β coordinate systemLfk_αAnd iLfk_β, by i obtained in step 9)* Lfk_αWith
i* Lfk_βI is individually subtractedLfk_αAnd iLfk_β, then it is K that acquired results are inputted to proportionality coefficient respectivelyPP controller in, to P control
The output result of device carries out α β/abc coordinate transform and obtains the modulated signal under abc coordinate system, and modulated signal is generated using PWM
Module obtains the switch control signal of inverter switching device network, for controlling inverter.
About the technical solution adopted by the present invention, in step 1), the corresponding fundamental wave feed line impedance Z of k-th of DGlk_fWith h times
Harmonic wave feed line impedance Zlk_h, it is expressed as in mathematical form
Zlk_f=Rlk+j·w0·Llk (1)
Zlk_h=Rlk+j·h·w0·Llk (2)
In formula: RlkAnd LlkThe corresponding feeder resistances of respectively k-th of DG and feeder line inductance, w0For the fundamental wave angular frequency of system
Rate.
About the technical solution adopted by the present invention, in step 2), the fundamental active function of inverter output in k-th of DG is calculated
The actual value P of rate and First Harmonic Reactive PowerDGk_fAnd QDGk_f, specific formula is as follows:
About the technical solution adopted by the present invention, in step 3), when line impedance is main with perception, under the fundamental wave of use
The control strategy that hangs down is as follows:
When line impedance with it is resistive for it is main when, the sagging control strategy of fundamental wave is as follows:
In formula: f*For the specified fundamental voltage frequency of DG output, V*For the specified fundamental voltage amplitude of DG output, P* DGk_fWith
Q* DGk_fRespectively DG exports the reference value of fundamental active power and First Harmonic Reactive Power, mkAnd nkThe respectively sagging system of fundamental active
The several and sagging coefficient of fundamental wave reactive power.
When resistive composition in line impedance and sensitive ingredients are not much different, theoretically fundamental active power and fundamental wave reactive power
There are stronger couplings between power, and the sagging control strategy of fundamental wave cannot achieve fundamental active power and First Harmonic Reactive Power at this time
Accurate distribution.In this case, resistive composition or sensitive ingredients therein are balanced out by introducing negative virtual impedance, made equivalent
Line impedance present it is pure perception or purely resistive, to eliminate the coupling of fundamental active power and First Harmonic Reactive Power.
About the technical solution adopted by the present invention, in step 4), the residual capacity S of k-th of DG is calculatedDGk_remaining, tool
Body formula is as follows:
About the technical solution adopted by the present invention, in step 5), Z is establishedDGk_h_eq-SDGk_remainingSagging relationship, specifically
Formula is as follows:
ZDGk_h_eq=Z0_h-ah·SDGk_remaining (10)
In formula: Z0_hFor using ZDGk_h_eq-SDGk_remainingAfter sagging relationship, when the residual capacity of DG is 0, each DG
Equivalent Harmonic impedance, i.e. Z0_hIt is all identical, Z for every DG unit0_hValue needs comprehensively consider to PCC voltage
The precision of the influence of THD and harmonic power distribution；ahFor the Z of each DGDGk_h_eq-SDGk_remainingHarmonic impedance in sagging relationship
Sagging coefficient, i.e. ahIt is also all identical, a for each DG unithValue can for plural number.By observing the structure on the right of above formula,
It knows because of Z0_hAnd ahIt is all identical, the Equivalent Harmonic impedance Z of each DG on institute's above formula left side for every DGDGk_h_eqIt
Between difference only by each DG on the right of above formula residual capacity SDGk_remianingBetween difference determine.And since each DG is in parallel
, the harmonic voltage of port is equal, so harmonic power is distributed between each DG can be equivalent to distribution harmonic current, this
It can be realized by controlling the Equivalent Harmonic impedance of each DG.Therefore, ZDGk_h_eq-SDGk_remainingSagging relationship may be implemented by
According to the target of the residual capacity distribution harmonic power of each DG.
About the technical solution adopted by the present invention, in step 6), it is virtually humorous to calculate h time for needing to introduce in k-th of DG
Wave impedance Zvk_h, specific formula is as follows:
Zvk_h=ZDGk_h_eq-Zlk_h (11)
Formula (10) are substituted into above formula, can be obtained
Zvk_h=Z0_h-ah·SDGk_remaining-Zlk_h (12)
About the technical solution adopted by the present invention, in step 7), the h subharmonic electricity of inverter output in k-th of DG is calculated
The reference value v of pressure* DGk_h, specific formula is as follows:
About the technical solution adopted by the present invention, in step 8), the reference value of inverter output voltage in k-th of DG is calculated
v* DGk, specific formula is as follows:
About the technical solution adopted by the present invention, in step 9), the transmission function of used PR controller are as follows:
In formula: wfFor the angular frequency of fundamental wave, KPRFor proportionality coefficient, Kf、KhAnd wbFor the parameter of resonance item.
Compared with the prior art, the invention has the following advantages:
1) Z that the present invention constructsDGk_h_eq-SDGk_remainingIn sagging relationship, the Equivalent Harmonic impedance Z of each DGDGk_h_eqIt
Between difference only by each DG residual capacity SDGk_remianingBetween difference determine.And the existing virtual harmonic impedance of introducing
In method, the expression formula of constructed virtual harmonic impedance will receive the influence of multiple variables, to make the Equivalent Harmonic of each DG
Difference between impedance can not uniquely be determined by the difference between the residual capacity of each DG, it is caused to have in distribution harmonic power
There is certain irrationality.Therefore, the present invention is relative to the existing method for introducing virtual harmonic impedance, in the equivalent of control DG
It is more reasonable when harmonic impedance, it can more accurately realize the target of the residual capacity distribution harmonic power by DG.
2) S in the present inventionDGk_remianingCalculating require no knowledge about each harmonic power of each DG output, and it is existing right
Each harmonic constructs the method for sagging relationship between harmonic wave active and reactive power and harmonic voltage frequency, amplitude respectively and has
The virtual harmonic impedance of introducing method, the accurate of each harmonic power for knowing each DG output is required in control algolithm
Value.Therefore, the present invention relative to it is existing each harmonic is constructed respectively harmonic wave active and reactive power and harmonic voltage frequency,
The method of sagging relationship and the existing method for introducing virtual harmonic impedance, more easy in measurement, workload between amplitude
It is smaller.
3) Z that the present invention constructsDGk_h_eq-SDGk_remainingSagging relationship distinguishes structure to each harmonic relative to existing
Build the method for sagging relationship and the existing virtual harmonic wave of introducing between harmonic wave active and reactive power and harmonic voltage frequency, amplitude
The method of impedance, it is more succinct in mathematical form, it is thus necessary to determine that parameter it is less.Therefore, the present invention is relative to existing to each
Subharmonic constructs between harmonic wave active and reactive power and harmonic voltage frequency, amplitude the method for sagging relationship and existing respectively
The method for introducing virtual harmonic impedance is more easy in control.
Detailed description of the invention
Fig. 1 is the typical isolated island micro-capacitance sensor structure chart comprising two DG and some linear loads and nonlinear load.
Fig. 2 is the control block diagram of inverter in kth (k=1,2) a DG, and the fundamental power computing module in Fig. 2 includes
Abc/dq coordinate transform and fundamental power calculate two parts.
Fig. 3 is the harmonic wave of DG residual capacity and DG output when not using harmonic power distribution method proposed by the invention
The simulation result schematic diagram of current effective value.Wherein, Fig. 3 (a) is DG residual capacity, and Fig. 3 (b) is that the harmonic current of DG output has
Valid value.
When Fig. 4 is using harmonic power distribution method proposed by the invention, the harmonic wave electricity of DG residual capacity and DG output
Flow the simulation result schematic diagram of virtual value.Wherein, Fig. 4 (a) is DG residual capacity, and Fig. 4 (b) is that the harmonic current of DG output is effective
Value.
Fig. 5 is the fundamental power of DG output when not using harmonic power distribution method proposed by the invention.
When Fig. 6 is using harmonic power distribution method proposed by the invention, the fundamental power of DG output.
Specific embodiment
The present invention is described in further details with reference to the accompanying drawing.
Referring to Fig.1, in isolated island micro-capacitance sensor DG1 and DG2 be it is in parallel, the harmonic voltage of respective port be it is equal, because
This distributes harmonic power between DG1 and DG2 can be equivalent to distribution harmonic current, and control can be passed through by distributing harmonic current
The relative size of the respective Equivalent Harmonic impedance of DG1 and DG2 is realized.In Fig. 1, the feed line impedance of setting DG1 and DG2 is
Purely resistive.
Referring to Fig. 2, the control program of inverter uses Double closed-loop of voltage and current, voltage in kth (k=1,2) a DG
The reference of outer ring is superimposed after being sought respectively by fundamental wave part and harmonic and obtains.The effect of the control program is to pass
On the basis of defeated fundamental power, pass through the Z of buildingDGk_h_eq-SDGk_remainingSagging relationship, the Equivalent Harmonic resistance of dynamic regulation DG
It is anti-, so that harmonic power be enable to be allocated according to the residual capacity of DG.The control program specifically carries out as follows:
Step 1), to the three-phase current i of inverter reality output in k-th of DGDGkWith the three-phase voltage v of reality outputDGk
It measures, then to iDGkAnd uDGkRespective fundametal compoment i is obtained after being filteredDGk_fAnd vDGk_f, to iDGk_fAnd vDGk_f
It carries out abc/dq coordinate transform and obtains the dq component I of inverter output fundamental current and fundamental voltageDGk_f_d、IDGk_f_q、VDGk_f_d
And VDGk_f_q, and the actual value of inverter exports in k-th of DG fundamental active power and First Harmonic Reactive Power is calculated
PDGk_fAnd QDGkf, correlation formula are as follows:
Step 2), the fundamental active power that inverter in k-th of DG obtained in step 1) is exported and fundamental wave reactive power function
The actual value P of rateDGk_fAnd QDGk_fIt is updated in the sagging control strategy of fundamental wave, obtains the frequency of inverter output voltage in k-th of DG
Rate fDGkWith amplitude VDGk_f, by frequency fDGkPhase theta is obtained to time integral multiplied by 2 π and by result, is then enabled inverse in k-th of DG
Become the d shaft voltage component of device output as VDGk_f, and the q shaft voltage component for enabling it export is 0, is obtained by dq/abc coordinate transform
The reference value v for the fundamental voltage that inverter exports in k-th of DG under abc coordinate system* DGk_f, correlation formula are as follows:
Step 3), the fundamental active power and fundamental wave reactive power function of inverter output in k-th of the DG obtained according to step 1)
The actual value P of rateDGk_f、QDGk_fAnd the rated capacity S of k-th given of DGDGk_ratedThe residual capacity of k-th of DG is calculated
SDGk_remaining, correlation formula are as follows:
Step 4), the residual capacity S for k-th of DG that step 3) is obtainedDGk_remainingSubstitute into the Z of buildingDGk_h_eq-
SDGk_remainingIn sagging relationship, the h equivalent harmonic impedance Z for k-th of DG that expectation is realized is obtainedDGk_h_eq, correlation formula are as follows:
ZDGk_h_eq=Z0_h-ah·SDGk_remaining
Step 5), the Z that step 4) is obtainedDGk_h_eqSubtract the corresponding h subharmonic feed line impedance Z of k-th of DGlk_h, obtain
The virtual harmonic impedance Z of h times for needing to introduce in k-th of DGvk_h, correlation formula are as follows:
Zvk_h=ZDGk_h_eq-Zlk_h=Z0_h-ah·SDGk_remaining-Zlk_h
Step 6) measures step 1) the three-phase current i of inverter reality output in k-th obtained of DGDGkIt is filtered
Wave obtains h three phase harmonic electric current i of its reality outputDGk_h, by iDGk_hThe Z obtained with step 5)vk_hIt is multiplied and then takes result
Opposite number, as in k-th of DG inverter export h subharmonic voltage reference value v* DGk_h, correlation formula are as follows:
Step 7), the reference value v of the fundamental voltage of inverter output in k-th of DG that step 2) is obtained* DGk_fWith step
6) the reference value v for the h subharmonic voltage that inverter exports in k-th of the DG obtained* DGk_hIt is added, considers main low-order harmonic,
That is h=5,7,11,13, obtain the reference value v of inverter output voltage in k-th of DG* DGk, to v* DGkAbc/ α β coordinate is carried out to become
It changes, obtains v* DGkComponent v under α β coordinate system* DGk_αAnd v* DGk_β, as the reference of outer voltage, correlation formula are as follows:
Step 8) measures step 1) the three-phase voltage v of inverter reality output in k-th obtained of DGDGkCarry out abc/
α β coordinate transform, obtains vDGkComponent v under α β coordinate systemDGk_αAnd vDGk_β, v that step 8) is obtained* DGk_αAnd v* DGk_βPoint
V is not subtractedDGk_αAnd vDGk_β, acquired results are inputted respectively in PR controller, using the output result of PR controller as electricity
Flow the reference i of inner ring* Lk_αAnd i* Lk_β.The transmission function of used PR controller are as follows:
Step 9), to inverter side filter inductance L in k-th of DGkOn electric current iLkIt measures and carries out abc/ α β seat
Mark transformation, obtains iLkComponent i under α β coordinate systemLk_αAnd iLk_β, by i obtained in step 8)* Lk_αAnd i* Lk_βIt is individually subtracted
iLk_αAnd iLk_β, then it is K that acquired results are inputted to proportionality coefficient respectivelyPP controller in, to the output result of P controller into
Coordinate transform of going obtains the modulated signal under abc coordinate system, and modulated signal obtains inverter switching device using PWM generation module
The switch control signal of network, for controlling inverter.
In MATLAB/Simulink emulation, for isolated island micro-grid system shown in FIG. 1, in order to realize that DG residue is held
The dynamic change of amount increases a linear load at the Time=1.5s moment.Fig. 3, Fig. 4, Fig. 5 and Fig. 6 are simulation result.Figure
In 3 and Fig. 4, SDGk_remainingIndicate the residual capacity of k-th of DG, IDGk_a_h_RMSIndicate that the harmonic current of k-th of DG output has
Valid value, IDGk_a_h_RMSIn footmark a indicate a phase.Since DG1 and DG2 are in parallel, thus harmonic power is distributed and harmonic current
Distribution is of equal value.In Fig. 5 and Fig. 6, SDGk_fIndicate that the actual value of the fundamental power of k-th of DG output, expression formula are
Referring to Fig. 3, for isolated island micro-grid system shown in FIG. 1, when not using harmonic power proposed by the invention point
When method of completing the square, after the Time=1.5s moment increases a linear load, the residual capacity of DG2 is held less than the remaining of DG1
Amount, but the harmonic current virtual value of DG2 output is but greater than the harmonic current virtual value of DG1 output, the i.e. harmonic wave that DG2 is assigned to
Power is greater than the harmonic power that DG1 is assigned to.This harmonic power distribution condition is unreasonable.Therefore, simulation result shows
When not using harmonic power distribution method proposed by the invention, harmonic power cannot be according to the respective remaining appearance of DG1 and DG2
Amount is allocated.
Isolated island micro-grid system shown in FIG. 1 is distributed when using harmonic power proposed by the invention referring to Fig. 4
When method, after the Time=1.5s moment increases a linear load, the residual capacity of DG2 is less than the residual capacity of DG1,
The harmonic current virtual value of DG2 output simultaneously is again smaller than the harmonic current virtual value that DG1 is exported, i.e. harmonic wave function that DG2 is assigned to
Rate is again smaller than the harmonic power that DG1 is assigned to.This harmonic power distribution condition is reasonable.Therefore, simulation result shows
When using harmonic power distribution method proposed by the invention, harmonic power can according to the respective residual capacity of DG1 and DG2 into
Row distribution.
Referring to figure 5 and figure 6, for isolated island micro-grid system shown in FIG. 1, not using and using proposed by the invention
When harmonic power distribution method, the allocation result of fundamental power is identical between DG1 and DG2, it is known that is mentioned using the present invention
Harmonic power distribution method out, which will not influence, distributes fundamental power between DG1 and DG2.
Claims (10)
1. a kind of isolated island micro-capacitance sensor harmonic power distribution method based on harmonic impedance control, which is characterized in that including following step
It is rapid:
Step 1) measures the corresponding fundamental wave feed line impedance Z of k-th of DG in isolated island micro-capacitance sensor after each DG installationlk_fWith h times
Harmonic wave feed line impedance Zlk_h；
Step 2), measurement obtain the three-phase current of inverter reality output in k-th of DG filtered after link by LC in DG
iDGkWith the three-phase voltage v of reality outputDGk, to iDGkAnd vDGkRespective fundametal compoment i is obtained after filteringDGk_fAnd vDGk_f, right
iDGk_fAnd vDGk_fIt carries out abc/dq coordinate transform and obtains the dq component I of inverter output fundamental current and fundamental voltageDGk_f_d、
IDGk_f_q、VDGk_f_dAnd VDGk_f_q, and inverter exports in k-th of DG fundamental active power and fundamental wave reactive power function is calculated
The actual value P of rateDGk_fAnd QDGk_f；
Step 3), the fundamental active power that inverter in k-th of DG obtained in step 2) is exported and First Harmonic Reactive Power
Actual value PDGk_fAnd QDGk_fIt is updated in the sagging control strategy of fundamental wave, obtains the frequency of inverter output voltage in k-th of DG
fDGkWith amplitude VDGk_f, by frequency fDGkPhase theta is obtained to time integral multiplied by 2 π and by result, then enables inversion in k-th of DG
The d shaft voltage component of device output is VDGk_f, and the q shaft voltage component for enabling it export is 0, is obtained by dq/abc coordinate transform
The reference value v for the fundamental voltage that inverter exports in k-th of DG under abc coordinate system* DGk_f；
Step 4), the fundamental active power of inverter output and First Harmonic Reactive Power in k-th of the DG obtained according to step 2)
Actual value PDGk_f、QDGk_fAnd the rated capacity S of k-th given of DGDGk_ratedThe residual capacity of k-th of DG is calculated
SDGk_remaining；
Step 5) establishes the sagging relationship between the h equivalent harmonic impedance of k-th of DG and its residual capacity, i.e. ZDGk_h_eq-
SDGk_remainingSagging relationship, the residual capacity S for k-th of DG that step 4) is obtainedDGk_remainingSubstitute into ZDGk_h_eq-
SDGk_remainingIn sagging relationship, the h equivalent harmonic impedance Z for k-th of DG that expectation is realized is obtainedDGk_h_eq；
Step 6), the Z that step 5) is obtainedDGk_h_eqSubtract the corresponding h subharmonic feed line impedance of k-th of DG that step 1) obtains
Zlk_h, obtain h times that needs to introduce in k-th of DG virtual harmonic impedance Zvk_h；
Step 7) measures step 2) the three-phase current i of inverter reality output in k-th obtained of DGDGkIt is filtered, obtains
To h three phase harmonic electric current i of its reality outputDGk_h, by iDGk_hThe Z obtained with step 6)vk_hIt is multiplied and then takes the phase of result
Anti- number, the reference value v as the h subharmonic voltage that inverter in k-th of DG exports* DGk_h；
Step 8), the reference value v of the fundamental voltage of inverter output in k-th of DG that step 3) is obtained* DGk_fIt is obtained with step 7)
To k-th of DG in inverter output h subharmonic voltage reference value v* DGk_hIt is added, considers main low-order harmonic, i.e. h
=5,7,11,13, then obtain the reference value v of inverter output voltage in k-th of DG* DGk, to v* DGkAbc/ α β coordinate is carried out to become
It changes, obtains v* DGkComponent v under α β coordinate system* DGk_αAnd v* DGk_β, reference as outer voltage；
Step 9) measures step 2) the three-phase voltage v of inverter reality output in k-th obtained of DGDGkAbc/ α β is carried out to sit
Mark transformation, obtains vDGkComponent v under α β coordinate systemDGk_αAnd vDGk_β, v that step 8) is obtained* DGk_αAnd v* DGk_βSubtract respectively
Remove vDGk_αAnd vDGk_β, acquired results are inputted respectively in PR controller, using the output result of PR controller as electric current in
The reference i of ring* Lfk_αAnd i* Lfk_β；
Step 10) obtains inverter side filter inductance L in k-th of DG by measurementfkOn electric current iLfk, to iLfkCarry out abc/ α
β coordinate transform, obtains iLfkComponent i under α β coordinate systemLfk_αAnd iLfk_β, by i obtained in step 9)* Lfk_αAnd i* Lfk_βPoint
I is not subtractedLfk_αAnd iLfk_β, then it is K that acquired results are inputted to proportionality coefficient respectivelyPP controller in, to the defeated of P controller
Result carries out α β/abc coordinate transform and obtains the modulated signal under abc coordinate system out, and modulated signal is obtained using PWM generation module
To the switch control signal of inverter switching device network, for controlling inverter.
2. the isolated island micro-capacitance sensor harmonic power distribution method according to claim 1 based on harmonic impedance control, feature
It is, in step 1), the corresponding fundamental wave feed line impedance Z of k-th of DGlk_fWith h subharmonic feed line impedance Zlk_h, in mathematical form
It is expressed as
Zlk_f=Rlk+j·w0·Llk (1)
Zlk_h=Rlk+j·h·w0·Llk (2)
In formula: RlkAnd LlkThe corresponding feeder resistances of respectively k-th of DG and feeder line inductance, w0For the fundamental wave frequency of system.
3. the isolated island micro-capacitance sensor harmonic power distribution method according to claim 1 based on harmonic impedance control, feature
It is, in step 2), to iDGk_fAnd vDGk_fIt is coordinately transformed to obtain dq points of inverter output fundamental current and fundamental voltage
Measure IDGk_f_d、IDGk_f_q、VDGk_f_dAnd VDGk_f_q, and inverter exports in k-th of DG fundamental active power and base is calculated
The actual value P of wave reactive powerDGk_fAnd QDGk_f, specific formula is as follows:
4. the isolated island micro-capacitance sensor harmonic power distribution method according to claim 1 based on harmonic impedance control, feature
It is, in step 3), the sagging control strategy of the fundamental wave of use is to realize in the case where no communication between each DG rationally
The target of fundamental power is distributed, concrete form needs are determined according to the property of line impedance, when line impedance is based on perception
When, the sagging control strategy of fundamental wave is as follows:
When line impedance with it is resistive for it is main when, the sagging control strategy of fundamental wave is as follows:
In formula: f*For the specified fundamental voltage frequency of DG output, V*For the specified fundamental voltage amplitude of DG output, P* DGk_fWith
Q* DGk_fRespectively DG exports the reference value of fundamental active power and First Harmonic Reactive Power, mkAnd nkThe respectively sagging system of fundamental active
The several and sagging coefficient of fundamental wave reactive power；
When resistive composition in line impedance and sensitive ingredients are not much different, resistance therein is balanced out by introducing negative virtual impedance
Property ingredient or sensitive ingredients, make equivalent line impedance that pure perception or purely resistive be presented, to eliminate fundamental active power and fundamental wave
The coupling of reactive power.
5. the isolated island micro-capacitance sensor harmonic power distribution method according to claim 1 based on harmonic impedance control, feature
It is, in step 4), the actual value P of the fundamental active power and First Harmonic Reactive Powers that exported by inverter in k-th of DGDGk_f、
QDGk_fAnd the rated capacity S of k-th given of DGDGk_ratedThe residual capacity S of k-th of DG is calculatedDGk_remaining, specifically
Formula is as follows:
6. the isolated island micro-capacitance sensor harmonic power distribution method according to claim 1 based on harmonic impedance control, feature
It is, in step 5), establishes ZDGk_h_eq-SDGk_remainingSagging relationship, specific formula is as follows:
ZDGk_h_eq=Z0_h-ah·SDGk_remaining (10)
In formula: Z0_hFor using ZDGk_h_eq-SDGk_remainingAfter sagging relationship, when the residual capacity of DG is 0, each DG etc.
Imitate harmonic impedance, i.e. Z0_hIt is all identical, Z for every DG unit0_hValue needs comprehensively consider to PCC voltage THD's
Influence the precision with harmonic power distribution；ahFor the Z of each DGDGk_h_eq-SDGk_remainingHarmonic impedance in sagging relationship is sagging
Coefficient, i.e. ahIt is also all identical for each DG unit.
7. the isolated island micro-capacitance sensor harmonic power distribution method according to claim 6 based on harmonic impedance control, feature
It is, in step 6), by ZDGk_h_eqSubtract the corresponding h subharmonic feed line impedance Z of k-th of DGlk_h, obtain needing in k-th of DG
The virtual harmonic impedance Z of h times of middle introducingvk_h, specific formula is as follows:
Zvk_h=ZDGk_h_eq-Zlk_h (11)
Formula (10) are substituted into above formula, can be obtained
Zvk_h=Z0_h-ah·SDGk_remaining-Zlk_h (12)。
8. the isolated island micro-capacitance sensor harmonic power distribution method according to claim 1 based on harmonic impedance control, feature
It is, in step 7), by iDGk_hWith Zvk_hIt is multiplied and then takes the opposite number of result, h times exported as inverter in k-th of DG
The reference value v of harmonic voltage* DGk_h, specific formula is as follows:
9. the isolated island micro-capacitance sensor harmonic power distribution method according to claim 1 based on harmonic impedance control, feature
It is, in step 8), the reference value v for the fundamental voltage that inverter in k-th of DG is exported* DGk_fIt is defeated with inverter in k-th of DG
The reference value v of h subharmonic voltage out* DGk_hIt is added, obtains the reference value v of inverter output voltage in k-th of DG* DGk, specifically
Formula is as follows:
10. the isolated island micro-capacitance sensor harmonic power distribution method according to claim 1 based on harmonic impedance control, feature
It is, in step 9), the transmission function of used PR controller are as follows:
In formula: wfFor the angular frequency of fundamental wave, KPRFor proportionality coefficient, Kf、KhAnd wbFor the parameter of resonance item.
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