CN105226727B - Microgrid inverter parallel power based on simulated capacitance divides equally control method - Google Patents
Microgrid inverter parallel power based on simulated capacitance divides equally control method Download PDFInfo
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Abstract
The invention discloses the microgrid inverter parallel power based on simulated capacitance to divide equally control method, this method obtains voltage magnitude and angle values using the power outer shroud of power outer shroud control algolithm first, then simulated capacitance algorithm is added, obtain output voltage amplitude and phase angle instruction, line output voltage capacitance current double-closed-loop control of going forward side by side.Simulated capacitance algorithm simulates inverter output end shunt capacitance characteristic by control algolithm, inverter output voltage and reactive power is adjusted, simulated capacitance value is calculated according to each inverter output reactive power size and the sagging formula of electric capacity.The present invention without interconnected communication between inverter and on line impedance detection, can adaptive equalization line impedance pressure drop, improve each inverter reactive power and divide equally ability and output voltage precision.
Description
Technical field
The invention belongs to power-sharing control field during microgrid inverter parallel connection islet operation, and in particular to one kind is based on
The microgrid inverter power-sharing control method of simulated capacitance algorithm.
Background technology
With environment, energy problem be on the rise and photovoltaic, wind-powered electricity generation distributed generation technology development and extensively should
With micro-grid system turns into the focus of research.To improve system reliability and redundancy, the dependence to communication is reduced, under more uses
Vertical control or the voltage source inverter networking of virtual synchronous motor control, realize effective bearing power distribution.
Due to the inductive elements such as filter inductance, isolating transformer be present in inverter circuit structure, its output impedance and line
Roadlock is anti-main in perception, therefore, the ratio of each inverter active power of output and active sagging coefficient in the case of systematic steady state
Relevant, the ratio of each inverter output reactive power and idle sagging coefficient and line impedance are relevant.Microgrid is everywhere under stable state
Angular frequency is identical, and load active power can be realized respectively, i.e. Po1/Po2/……/Pon=Prate1/Prate2/……/Praten, its
Middle PoiFor inverter #i active power of output, PrateiFor inverter #i rated active powers；And because each distributed power source is geographical
Position has randomness, and parallel line impedance is difficult to match with rated capacity, therefore conventional droop control and virtual synchronous electricity
Machine control can not realize that reactive load is divided equally, i.e. Qo1/Qo2/……/Qon≠Qrate1/Qrate2/……/Qraten, wherein QoiTo be inverse
Become device #i output reactive powers, QrateiFor inverter #i rated reactive powers.Each inverter can not be respectively idle in micro-grid system
Load can cause some distributed power sources to overload, or even influence the stable operation of system.Therefore, realize each microgrid inverter according to
Its rated capacity load-sharing power is very necessary.
At present, analyzed simultaneously for the power-sharing problem of microgrid inverter parallel running, existing more scientific papers
Solution is proposed, such as：
1st, entitled " Robust droop controller for accurate proportional load sharing
Among inverters operated in parallel ", Zhong Q C, et al,《IEEE Transactions on
Industrial Electronics》, 2013,60 (4):(" it is equal that shunt chopper precise load power can be achieved in 1281-1290
The robust droop control device divided ",《IEEE journals --- industrial electronic periodical》, the 4th 1390-1402 pages of the phase of volume 60 in 2013)
The virtual value of article sampling common load voltage simultaneously adds voltage magnitude integral element, the method in traditional droop control algorithm
Make not influenceed by line impedance dividing equally for shunt chopper power, and eliminate load caused by line drop and droop control
The problem of pressure drop offrating, but the method has the following disadvantages:
1) each inverter need to additionally increase load voltage detection device and sense channel, so as to add cost, be unfavorable for
Project Realization；
2) detection error of load voltage can cause the respectively error of power, divide equally error to reduce, need to increase sagging
Coefficient, and the increase of sagging coefficient can influence the stability of system.
2nd, entitled " An enhanced microgrid load demand sharing strategy ", He J, Li Y
W.,《IEEE Transactions on Power Electronics》, 2012,27 (9):3984-3995 be (" a kind of raising
Microgrid load sharing strategy ",《IEEE journals --- power electronics periodical》, the 9th 3984-3995 pages of the phase of volume 27 in 2012) and text
The compensation term of reactive power is added in chapter in the active droop control equation of tradition, is added in the idle droop control equation of tradition
The compensation term of active power deviation, so that each inverter reaches new steady s tate and realizes accurate power-sharing.But this
Method has the following disadvantages：
1) signal of compensation term is that timing is sent, and can not realize that realtime power compensates；
2) need signal to control each inverter while add compensation term, and be in the steady-state process for compensating and reaching new is added
System load can not change；System voltage frequency and amplitude the deviation increase of new steady s tate.
3rd, entitled " An accurate power control strategy for power-electronics-
interfaced distributed generation units operating in a low-voltage multibus
Microgrid ", Li Y W, Kao C N.,《IEEE Transactions on Power Electronics》, 2009,24
(12):2977-2988 (" the accurate power control strategy of power electronics interface generator unit in low pressure micro-capacitance sensor ",《IEEE
Report --- Electrical electronic journal》, the 12nd 2977-2988 pages of the phase of volume 24 in 2009) in article first by inverter parallel
Bulk power grid detects its on line impedance, then changes sagging curve according on line impedance value, so as to realize accurate power-sharing, but
The deficiency of this scheme is：The detection of microgrid inverter on line impedance needs bulk power grid in parallel, and is carried out according to certain step, microgrid knot
Structure changes at random such as the position of inverter and load, and on line impedance value can not follow the change of microgrid structure to examine again
Survey, the applicability of the method during so as to limit microgrid structure change.
The content of the invention
Each inverter can not be divided equally by its rated capacity during the present invention seeks to for microgrid inverter isolated island parallel running
The problem of bearing power, there is provided a kind of microgrid inverter based on simulated capacitance is in parallel to divide equally control method, without between inverter
Interconnected communication and on line impedance detection, can adaptive equalization line impedance pressure drop, improve each inverter reactive power and divide equally ability
With output voltage precision.
To achieve the above object, present invention employs following technical scheme：The invention provides one kind to be based on simulated capacitance
Microgrid inverter parallel power divide equally control method, include the collection of microgrid inverter output phase voltage, it is characterised in that main
Want step as follows：
1st, a kind of microgrid inverter parallel power based on simulated capacitance divides equally control method, including microgrid inverter output
The collection of phase voltage, it is characterised in that key step is as follows：
Step 1, microgrid inverter number of units is set as n, and n >=2, #i represent inverter numbering, and i ∈ [2, n]；
Step 2, sampling microgrid inverter #i output phase voltages Uoai,Uobi, bridge arm inductive current ILai,ILbi, and through single same
Step rotating coordinate transformation obtains output voltage dq axis components Uodi,UoqiWith the component I of inductive current dq axlesLdi,ILqi, wherein d axles
For active axle, q axles are idle axle；
Step 3, the microgrid inverter #i obtained in step 2 exported into phase voltage Uoai,UobiCarry out differential calculation and draw electricity
Capacitance current Icai,Icbi, and obtain d axle capacitance current components I through single synchronous rotating anglecdiWith q axle capacitance current components
Icqi；
Step 4, according to the output voltage dq axis components U obtained in step 2odi,UoqiWith the component of inductive current dq axles
ILdi,ILqiInverter output instantaneous active power and reactive power are calculated, and is filtered through low-pass first order filter, is put down
Equal active-power PoiWith average reactive power Qoi；
Step 5, according to the average active power P obtained in step 4oiWith average reactive power Qoi, through overpower outer shroud control
Algorithm processed obtains d shaft voltages instruction Edrefiθ is instructed with phase anglerefi；
Step 6, q shaft voltages are made to instruct Eqrefi=0, and E is instructed according to d shaft voltages in step 5drefi, by simulated capacitance
Algorithm obtains output voltage closed loop d axles instruction Edrefi_virE is instructed with output voltage closed loop q axlesqrefi_vir；
Step 7, by the output voltage closed loop d axles obtained in step 6 instruct Edrefi_virWith the output electricity obtained in step 2
Press d axis components Uodi, by d shaft voltage closed-loop control equations, obtain d axles capacitance current instruction Icdrefi；By what is obtained in step 6
Output voltage closed loop q axles instruct Eqrefi_virWith the output voltage q axis components U obtained in step 2oqi, by q shaft voltage closed loop controls
Equation processed, obtain q axles capacitance current instruction Icqrefi；
Step 8, by the d axles capacitance current obtained in step 7 instruct IcdrefiWith the d axles capacitance current point obtained in step 3
Measure Icdi, by d shaft current closed-loop control equations, obtain d axle output signal Usidi；The q axle capacitance currents obtained in step 7 are referred to
Make IcqrefiWith the q axle capacitance current components I obtained in step 3cqi, by q shaft current closed-loop control equations, obtain the output of q axles
Signal Uiqi；
Step 9, by the output voltage d axles obtained in step 6 instruct Edrefi_virE is instructed with output voltage q axlesqrefi_virMake
Feedovered for voltage instruction, respectively plus the d axle output signal Us obtained in step 8idiWith q axle output signal Usiqi, obtain dq coordinates
Modulating wave U under systemmdiAnd Umqi；
Step 10, by the modulating wave U under dq coordinate systems in step 9mdiAnd UmqiObtained through single synchronously rotating reference frame inverse transformation
The three-phase modulations ripple U of inverter leg voltagemai,Umbi,Umci, the modulated rear drive signal as IGBT circuits.
Preferably, differential calculation is carried out described in step 3 and draws capacitance current Icai,IcbiCalculation formula be：
Icai=CfisUoai
Icbi=CfisUobi
Wherein CfiFor microgrid inverter #i filtering capacitance, s is Laplace operator.
Preferably, average active power P described in step 4oiWith average reactive power QoiCalculation formula is respectively：
Wherein TfFor the time constant of low-pass first order filter.
Preferably, power outer shroud control algolithm described in step 5 is droop control algorithm, and its calculation formula is：
Edrefi=E*-niQoi
θrefi=∫ (ω*-miPoi)
Wherein, E*For inverter rated output voltage amplitude, niFor the sagging coefficient of inverter #i reactive powers, ω*For inversion
The specified angular frequency of device, miFor the sagging coefficient of inverter #i active power.
Preferably, power outer shroud control algolithm described in step 5 is virtual synchronous motor control algorithms, and its calculation formula is：
Edrefi=E*-niQoi
Wherein, E*For inverter rated output voltage amplitude, niFor the sagging coefficient of inverter #i reactive powers, ω*For inversion
The specified angular frequency of device, miFor the sagging coefficient of inverter #i active power, J is the virtual rotation inertia of virtual synchronous motor.
Preferably, simulated capacitance algorithmic formula is described in step 6：
Edrefi_vir=Edrefi+ω0 2LiUodi(Cpi *-kciQoi),
Eqrefi_vir=Eqrefi+ω0 2LiUoqi(Cpi *-kciQoi),
And
Wherein ω0For fundamental wave angular frequency, LiFor inverter #i equivalent output impedances, Cpi *For maximum simulated capacitance value, kciFor
The sagging coefficient of simulated capacitance, QrateiFor inverter #i nominal reactive capacity, E*For inverter rated output voltage amplitude, niTo be inverse
Become the sagging coefficient of device #i reactive powers.
Preferably, d shaft voltages closed-loop control equation described in step 7 and q shaft voltage closed-loop control equations are respectively：
Icdrefi=(Edrefi_vir-Uodi)GV(s)
Icqrefi=(Eqrefi_vir-Uoqi)GV(s)
Wherein, GV(s) it is voltage close loop proportional and integral controller, its expression formula is：
GV(s)=kpvi+kivi/s
kpviFor inverter #i voltage close loop proportional controller coefficients, kiviFor integral controller coefficient, s calculates for Laplce
Son.
Preferably, d shaft currents closed-loop control equation described in step 8 and q shaft current closed-loop control equations are respectively：
Uidi=(Icdrefi-Icdi)GI(s)
Uiqi=(Icqrefi-Icqi)GI(s)
GI(s) it is current closed-loop proportional controller, its expression formula is：
GI(s)=kpi,
Wherein kpiFor inverter #i capacitance current closed loop proportional adjuster coefficients.
Microgrid inverter parallel power disclosed by the invention based on simulated capacitance divides equally control method, with existing microgrid
Inverter parallel power-sharing control method is compared, and its advantage is embodied in：
1st, parameter needed for this control method is the sampled value of voltage x current of each inverter itself, without increasing inverter
Between communication and extra sample devices, it is cost-effective；
2nd, without inverter on line impedance detection in this control method, therefore suitable for the micro-grid system of various structures, and
Realize simple；
3rd, because inverter output end shunt capacitance can increase its output voltage amplitude, simulated capacitance algorithm simulation inverter
Output end shunt capacitance characteristic, and according to each inverter output reactive power adaptive equalization line drop, improving idle work(
Rate improves voltage accuracy while dividing equally precision.
Brief description of the drawings
Fig. 1 is inverter parallel structure chart of the embodiment of the present invention.
Fig. 2 is inverter control structures block diagram of the embodiment of the present invention.
Fig. 3 is the equivalent circuit diagram of inverter output end shunt capacitance of the embodiment of the present invention.
Fig. 4 is concrete structure diagram of simulated capacitance of the embodiment of the present invention algorithm under dq reference axis.
Fig. 5 is that the shunt chopper of the embodiment of the present invention two adds active power of output waveform before and after simulated capacitance algorithm.
Fig. 6 is that the shunt chopper of the embodiment of the present invention two adds output reactive power waveform before and after simulated capacitance algorithm.
Fig. 7 is that the shunt chopper of the embodiment of the present invention two adds a phase currents and circulation before simulated capacitance algorithm.
Fig. 8 is that the shunt chopper of the embodiment of the present invention two adds a phase currents and circulation after simulated capacitance algorithm.
Fig. 9 is the shunt chopper of the embodiment of the present invention two respectively using virtual impedance algorithm and simulated capacitance algorithm
PCC dotted line voltage magnitudes.
Embodiment
The present embodiment is specifically described below in conjunction with the accompanying drawings.
Fig. 1 is 2 identical capacity microgrid inverter parallel systems, and inverter numbering is #i=1,2.Inverter #i direct currents
Press as 600V, rated output line voltage is 380V/50Hz, filter inductance value 0.5mH, filtering capacitance 200uF, inverter
Rated capacity is 100KVar.The impedance of inverter #1 on lines is ZL1=0.001+j0.004 Ω, the impedance of inverter #2 on lines are ZL2
=0.075+j0.025 Ω.
Fig. 2 is inverter control structures block diagram of the embodiment of the present invention.The step of control method of the present invention, is as follows：
Step 1：If microgrid inverter number of units is n, and n >=2, #i represent inverter numbering, and i ∈ [2, n].
In the present embodiment, n=2, inverter numbering #i is respectively #1 and #2.
Step 2：2 microgrid inverter #i output phase voltages U of samplingoai,Uobi, bridge arm inductive current ILai,ILbi, and through list
Synchronous rotating angle obtains output voltage dq axis components Uodi,UoqiWith inductive current dq component ILdi,ILqi, wherein d axles
For active axle, q axles are idle axle.
Step 3：The inverter output voltage U that will be obtained in step 2oai,UobiCarry out differential calculation and draw capacitance current
Icai,Icbi, and obtain capacitance current d axles and q axis components, capacitance current I through single synchronous rotating anglecai,IcbiCalculating
Formula is：
Icai=CfisUoai
Icbi=CfisUobi,
Wherein CfiFor inverter #i filtering capacitances, s is Laplace operator, C in the present embodimentfi=200uF.
Step 4：According to the dq components U of the output voltage axle obtained in step 2odi,UoqiWith inductive current dq component
ILdi,ILqiInverter output instantaneous active power and reactive power are calculated, and is filtered through low-pass first order filter, is put down
Equal active-power PoiWith average reactive power Qoi, average active power PoiWith average reactive power QoiCalculation formula is：
Wherein TfFor the time constant of low-pass first order filter.
Low-pass first order filter act as filtering out the noise harmonic wave of instantaneous power, is also acted as in droop control algorithm and pulls open work(
The effect of rate ring and Voltage loop control bandwidth.In virtual synchronous motor algorithm, due to virtual inertia be present, to reduce wave filter pair
The influence of system dynamic characteristic, TfValue is smaller, droop control can value it is bigger.Calculated in the present embodiment using virtual synchronous motor
The outer shroud of method, takes Tf=1e-4s.
Step 5：According to the average active power P obtained in step 4oiWith average reactive power Qoi, through overpower outer shroud control
Algorithm processed obtains d shaft voltages instruction Edrefiθ is instructed with phase anglerefi。
So that the impedance of inverter on line is in mainly perception as an example, power outer shroud control algolithm is droop control algorithm, and it is calculated
Formula is：
Edrefi=E*-niQoi
θrefi=∫ (ω*-miPoi)
Power outer shroud control algolithm is virtual synchronous motor control algorithms, and its calculation formula is：
Edrefi=E*-niQoi
Wherein, E*For inverter rated output voltage amplitude, niFor the sagging coefficient of inverter #i reactive powers, ω*For inversion
The specified angular frequency of device, miFor the sagging coefficient of inverter #i active power, J is the virtual rotation inertia of virtual synchronous motor.
niFor U-Q sagging curve slopes, when general value is that inverter exports rated capacity reactive power, voltage magnitude is most
Great fluctuation process 5%.miFor ω-P sagging curve slopes, when general value is that inverter exports rated capacity active power, voltage frequency
Rate maximum fluctuation 1%.J is the rotary inertia of virtual synchronous generator, and its size influences inverter during micro-grid system load change
Frequency response speed, and J values can influence the stability of a system beyond certain limit.Typically use inertia time constant H=J ω2/Srated
The inertia of synchronous motor is weighed, because virtual synchronous motor is that inverter simulates synchronous motor characteristic using control algolithm, it rings
Answer speed faster than actual synchronization motor.Inverter rated capacity S in the present embodimentrated=100Kvar, E*=220V, ω*=
314.159rad/s, H=0.5s is selected, m is calculatedi=1% ω*/Srated=3.14e-5rad/W, ni=2%E*/Srated
=4.4e-5V/Var, J=HSrated/ω2=0.5Kgm2。
Step 6：Q shaft voltages are made to instruct Eqrefi=0, and E is instructed according to d shaft voltages in step 5drefi, by simulated capacitance
Algorithm obtains output voltage closed loop d axles instruction Edrefi_virE is instructed with output voltage closed loop q axlesqrefi_vir。
Fig. 3 is inverter #i output end shunt capacitances CpiEquivalent circuit diagram, LiFor inverter #i equivalent outputting inductance,
LLiFor on line inductance, icFor shunt capacitance electric current, ioFor output current, erefiCalculated for droop control algorithm or virtual synchronous motor
The voltage instruction that method obtains, uoFor inverter output voltage.
Inverter output voltage u can be obtained by Fig. 3oi(s) with voltage instruction erefiAnd output current i (s)o(s) relation：
uoi(s)=erefi(s)-sLi(io(s)+ic(s))
=erefi(s)-s2LiCpieoi(s)-sLiio(s)
Therefore, the instruction of output voltage closed loop is after order addition simulated capacitance algorithm：
erefi_vir(s)=erefi(s)-s2LiCpieoi(s),
It can be achieved to use algorithm simulation inverter output end shunt capacitance characteristic.
Because output voltage need to carry out two subdifferentials in simulated capacitance algorithm, differentiating amplifies high-frequency noise, output
Voltage distortion, reduce system stability margin.In view of present invention is generally directed to the power of fundamental wave component in the case of systematic steady state is equal
Divide problem, the fundamental frequency part of algorithm can be only considered, with j ω0Instead of s, static virtual electric capacity algorithm is obtained：
Erefi_vir=Erefi+ω0 2LiCpiUoi,
Wherein ω0For fundamental wave angular frequency.
Because inverter output end shunt capacitance is bigger, output reactive power is bigger, for output reactive power QoiIt is smaller
Inverter, need larger capacitance C in parallelpi, therefore, according to sagging principle, make Cpi=Cpi *-kciQoi, obtain simulated capacitance algorithm
Formula：
Edrefi_vir=Edrefi+ω0 2LiUodi(Cpi *-kciQoi)
Eqrefi_vir=Eqrefi+ω0 2LiUoqi(Cpi *-kciQoi)
Wherein, Cpi *For maximum simulated capacitance value, kciFor the sagging coefficient of simulated capacitance, QrateiFor inverter #i nominal reactives
Capacity.
As inverter output reactive power QoiDuring=0Var, output voltage closed loop command value is maximum, and is system requirements
Maximum voltage value, therefore C can be tried to achievepi *：
And specified reactive power Q is exported according to sagging principle, inverterrateiWhen, corresponding CpiFor maximum Cpi *, so as to
Obtain kci：
Fig. 4 is concrete structure diagram of the simulated capacitance algorithm under dq reference axis.
According to each parameter of microgrid inverter in the present embodiment, C is calculated to obtainpi *=0.1F, kci=1e-6F/VA.
Step 7：The output voltage closed loop d axles obtained in step 6 are instructed into Edrefi_virWith the output electricity obtained in step 2
Press d axis components Uodi, by d shaft voltage closed-loop control equations, obtain d axles capacitance current instruction Icdrefi；Electricity will be exported in step 6
Press off ring q axles instruction Eqrefi_virOutput voltage q axis components U in 2 obtained with stepoqi, by q shaft voltages closed-loop control side
Journey, obtain q axles capacitance current instruction Icqrefi。
D shaft voltage closed-loop control equations and q shaft voltage closed-loop control equations are：
Icdrefi=(Edrefi_vir-Uodi)GV(s)
Icqrefi=(Eqrefi_vir-Uoqi)GV(s)
GV(s) it is voltage close loop proportional and integral controller, its expression formula is：
GV(s)=kpvi+kivi/ s,
kpviFor inverter #i voltage close loop proportional controller coefficients, kiviFor integral controller coefficient.
Voltage close loop control action is adjusted to enable output voltage preferably to follow command voltage using than understanding to divide
Save device, and when integrated load disturbs output voltage dynamic characteristic, select in the present embodiment voltage regulator parameter for：kpvi=
0.03, kivi=800.
Step 8：The d axles capacitance current obtained in step 7 is instructed into IcdrefiWith the d axles capacitance current point obtained in step 3
Measure Icdi, by d shaft current closed-loop control equations, obtain d axle output signal Usidi；The q axle capacitance currents obtained in step 7 are referred to
Make IcqrefiWith the q axle capacitance current components I obtained in step 3cqi, by q shaft current closed-loop control equations, obtain the output of q axles
Signal Uiqi。
D shaft current closed-loop control equations and q shaft current closed-loop control equations are:
Uidi=(Icdrefi-Icdi)GI(s)
Uiqi=(Icqrefi-Icqi)GI(s)
GI(s) it is current closed-loop proportional controller, its expression formula is：
GI(s)=kpi,
Wherein kpiFor inverter #i capacitance current closed loop proportional adjuster coefficients.
Capacitance current ring closure is improves inverter output voltage dynamic characteristic, to ensure its rapidity, current closed-loop
Adoption rate adjuster, k is selected in the present embodimentpi=0.03.
Step 9：The output voltage d axles obtained in step 6 are instructed into Edrefi_virE is instructed with q axlesqrefi_virRefer to as voltage
Order feedforward, respectively plus the d axle output signal Us obtained in step 8idiWith q axle output signal Usiqi, obtain the tune under dq coordinate systems
Ripple U processedmdiAnd Umqi。
Step 10：By the modulating wave U under dq coordinate systems in step 9mdiAnd UmqiObtained through single synchronously rotating reference frame inverse transformation
The three-phase modulations ripple U of inverter leg voltagemai,Umbi,Umci, the modulated rear drive signal as IGBT circuits.
Invention is applied to power ring using droop control algorithm and the list of virtual synchronous motor control algorithms in the present embodiment
Phase and three-phase microgrid inverter.Be below two identical capacity shown in Fig. 1 100KW parallel connection of three-phase inverter system add it is virtual
The simulation waveform of electric capacity algorithm.
Inverter power outer shroud uses virtual synchronous motor algorithm, parallel running during 0.6s, during 0.8s impact 100KW and
140KVar common loads, 2.2s add simulated capacitance algorithm.
Fig. 5 is inverter #1, #2 active power of output waveform, is added before and after simulated capacitance algorithm, two inverters are defeated all the time
Go out identical active power, after adding simulated capacitance algorithm, active power slightly increases, and is due to the increase of simulated capacitance algorithm
Caused by output voltage amplitude.
Fig. 6 is inverter #1, #2 output reactive power waveform, before adding simulated capacitance algorithm, due to inverter #1 on lines
Impedance is less than inverter #2, and inverter #1 output reactive powers are more than inverter #2, and reactive circular power flow is inverter rated current
14%.After adding simulated capacitance algorithm, reactive power divides equally error reduction, and reactive circular power flow is reduced to inverter rated current
5%.
For Fig. 7 to add inverter #1, #2 output a phase currents and circulation before simulated capacitance algorithm, Fig. 8 is addition simulated capacitance
Inverter #1 after algorithm, #2 export a phase currents and circulation.
Fig. 9 is inverter #1, and #2 adds the PCC line voltage amplitudes of virtual impedance algorithm and simulated capacitance algorithm.Due under
Vertical characteristic, decline 5% with line voltage after reactive load, virtual impedance algorithm makes PCC point voltages further reduce, and virtual impedance
Value need to estimate that line impedance parameter is designed.And simulated capacitance algorithm improves voltage essence while reactive circular power flow is reduced
Degree.Caused by voltage landing during 0.8s is shock load.
Claims (7)
1. a kind of microgrid inverter parallel power based on simulated capacitance divides equally control method, including microgrid inverter output phase electricity
The collection of pressure, it is characterised in that key step is as follows：
Step 1, microgrid inverter number of units is set as n, and n >=2, #i represent inverter numbering, and i ∈ [2, n]；
Step 2, sampling microgrid inverter #i output phase voltages Uoai,Uobi, bridge arm inductive current ILai,ILbi, and through single synchronous rotation
Turn coordinate transform and obtain output voltage dq axis components Uodi,UoqiWith the component I of inductive current dq axlesLdi,ILqi, wherein d axles are to have
Work(axle, q axles are idle axle；
Step 3, the microgrid inverter #i obtained in step 2 exported into phase voltage Uoai,UobiCarry out differential calculation and draw electric capacity electricity
Flow Icai,Icbi, and obtain d axle capacitance current components I through single synchronous rotating anglecdiWith q axle capacitance current components Icqi；
Step 4, according to the output voltage dq axis components U obtained in step 2odi,UoqiWith the component I of inductive current dq axlesLdi,ILqi
Inverter output instantaneous active power and reactive power are calculated, and is filtered through low-pass first order filter, is obtained averagely active
Power PoiWith average reactive power Qoi；
Step 5, according to the average active power P obtained in step 4oiWith average reactive power Qoi, control and calculate through overpower outer shroud
Method obtains d shaft voltages instruction Edrefiθ is instructed with phase anglerefi；
Step 6, q shaft voltages are made to instruct Eqrefi=0, and E is instructed according to d shaft voltages in step 5drefi, by simulated capacitance algorithm
Obtain output voltage closed loop d axles instruction Edrefi_virE is instructed with output voltage closed loop q axlesqrefi_vir；
The simulated capacitance algorithmic formula is：
Edrefi_vir=Edrefi+ω0 2LiUodi(Cpi *-kciQoi),
Eqrefi_vir=Eqrefi+ω0 2LiUoqi(Cpi *-kciQoi),
And
Wherein ω0For fundamental wave angular frequency, LiFor inverter #i equivalent output impedances, Cpi *For maximum simulated capacitance value, kciTo be virtual
The sagging coefficient of electric capacity, QrateiFor inverter #i nominal reactive capacity, E*For inverter rated output voltage amplitude, niFor inversion
The sagging coefficient of device #i reactive powers；
Step 7, by the output voltage closed loop d axles obtained in step 6 instruct Edrefi_virWith the output voltage d axles obtained in step 2
Component Uodi, by d shaft voltage closed-loop control equations, obtain d axles capacitance current instruction Icdrefi；The output that will be obtained in step 6
Voltage close loop q axles instruct Eqrefi_virWith the output voltage q axis components U obtained in step 2oqi, by q shaft voltages closed-loop control side
Journey, obtain q axles capacitance current instruction Icqrefi；
Step 8, by the d axles capacitance current obtained in step 7 instruct IcdrefiWith the d axle capacitance current components obtained in step 3
Icdi, by d shaft current closed-loop control equations, obtain d axle output signal Usidi；The q axles capacitance current obtained in step 7 is instructed
IcqrefiWith the q axle capacitance current components I obtained in step 3cqi, by q shaft current closed-loop control equations, obtain q axles output letter
Number Uiqi；
Step 9, by the output voltage d axles obtained in step 6 instruct Edrefi_virE is instructed with output voltage q axlesqrefi_virAs electricity
Pressure instruction feedforward, respectively plus the d axle output signal Us obtained in step 8idiWith q axle output signal Usiqi, obtain under dq coordinate systems
Modulating wave UmdiAnd Umqi；
Step 10, by the modulating wave U under dq coordinate systems in step 9mdiAnd UmqiInversion is obtained through single synchronously rotating reference frame inverse transformation
The three-phase modulations ripple U of device bridge arm voltagemai,Umbi,Umci, the modulated rear drive signal as IGBT circuits.
2. the microgrid inverter parallel power according to claim 1 based on simulated capacitance divides equally control method, its feature
It is：Differential calculation is carried out described in step 3 and draws capacitance current Icai,IcbiCalculation formula be：
Icai=CfisUoai
Icbi=CfisUobi
Wherein CfiFor microgrid inverter #i filtering capacitance, s is Laplace operator.
3. the microgrid inverter parallel power according to claim 1 based on simulated capacitance divides equally control method, its feature
It is：Average active power P described in step 4oiWith average reactive power QoiCalculation formula is respectively：
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Wherein TfFor the time constant of low-pass first order filter.
4. the microgrid inverter parallel power according to claim 1 based on simulated capacitance divides equally control method, its feature
It is：Power outer shroud control algolithm described in step 5 is droop control algorithm, and its calculation formula is：
Edrefi=E*-niQoi
θrefi=∫ (ω*-miPoi)
Wherein, E*For inverter rated output voltage amplitude, niFor the sagging coefficient of inverter #i reactive powers, ω*For inverter volume
Determine angular frequency, miFor the sagging coefficient of inverter #i active power.
5. the microgrid inverter parallel power according to claim 1 based on simulated capacitance divides equally control method, its feature
It is：Power outer shroud control algolithm described in step 5 is virtual synchronous motor control algorithms, and its calculation formula is：
Edrefi=E*-niQoi
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</mrow>
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Wherein, E*For inverter rated output voltage amplitude, niFor the sagging coefficient of inverter #i reactive powers, ω*For inverter volume
Determine angular frequency, miFor the sagging coefficient of inverter #i active power, J is the virtual rotation inertia of virtual synchronous motor.
6. the microgrid inverter parallel power according to claim 1 based on simulated capacitance divides equally control method, its feature
It is：D shaft voltages closed-loop control equation described in step 7 and q shaft voltage closed-loop control equations are respectively：
Icdrefi=(Edrefi_vir-Uodi)GV(s)
Icqrefi=(Eqrefi_vir-Uoqi)GV(s)
Wherein, GV(s) it is voltage close loop proportional and integral controller, its expression formula is：
GV(s)=kpvi+kivi/s
kpviFor inverter #i voltage close loop proportional controller coefficients, kiviFor integral controller coefficient, s is Laplace operator.
7. the microgrid inverter parallel power according to claim 1 based on simulated capacitance divides equally control method, its feature
It is：D shaft currents closed-loop control equation described in step 8 and q shaft current closed-loop control equations are respectively：
Uidi=(Icdrefi-Icdi)GI(s)
Uiqi=(Icqrefi-Icqi)GI(s)
GI(s) it is current closed-loop proportional controller, its expression formula is：
GI(s)=kpi,
Wherein kpiFor inverter #i capacitance current closed loop proportional adjuster coefficients.
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| CN106301055A (en) * | 2016-09-27 | 2017-01-04 | 天津大学 | Inverter parallel loop current suppression system based on virtual synchronous generator control strategy |
| CN107612025B (en) * | 2017-09-12 | 2019-11-08 | 西安交通大学 | Current-control type inverter improves control method in microgrid |
| CN109698517B (en) | 2017-10-23 | 2023-03-28 | 台达电子企业管理（上海）有限公司 | Method and device for controlling power system |
| CN108322049B (en) * | 2018-02-12 | 2020-09-25 | 西安理工大学 | Virtual capacitance control method for bidirectional direct current converter |
| CN109088439B (en) * | 2018-08-17 | 2022-01-11 | 江苏大学 | Control method of inverter parallel system based on secondary frequency modulation and virtual homopolar generator algorithm |
| CN109904881A (en) * | 2019-04-12 | 2019-06-18 | 中南大学 | A kind of cascade microgrid power based on adaptive simulated capacitance divides equally control method |
| CN110212513B (en) * | 2019-04-30 | 2023-07-14 | 华北电力大学（保定） | Flexible virtual capacitor control method for stabilizing voltage fluctuation of direct-current micro-grid bus |
| CN110148948B (en) * | 2019-05-23 | 2023-04-25 | 四川科陆新能电气有限公司 | Device and method for improving power generation power of photovoltaic inverter at tail end of power grid |
| CN112018803B (en) * | 2019-05-28 | 2022-03-15 | 内蒙古电力(集团)有限责任公司内蒙古电力科学研究院分公司 | Power control method and device based on parallel double inverters |
| CN110277803B (en) * | 2019-07-30 | 2021-02-12 | 西安西电电气研究院有限责任公司 | Virtual synchronous generator control method and control device of energy storage converter |
| CN110350507B (en) * | 2019-08-01 | 2020-11-03 | 华北电力大学（保定） | Method and device for determining equivalent capacitance of direct-current microgrid and computer-readable storage medium |
| CN111431211B (en) * | 2020-05-07 | 2021-06-08 | 合肥学院 | Micro-grid inverter parallel control method based on active curve droop |
| CN111463837B (en) * | 2020-05-18 | 2021-05-14 | 重庆大学 | Distributed power distribution method for multi-source hybrid power system |
| CN113258806B (en) * | 2021-04-14 | 2022-03-29 | 山东大学 | Virtual capacitor-based parallel converter model prediction control method and system |
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