CN106532685B - For the generalized impedance criterion calculation method of gird-connected inverter stability analysis and application - Google Patents
For the generalized impedance criterion calculation method of gird-connected inverter stability analysis and application Download PDFInfo
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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
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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
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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
- H02J2203/00—Indexing scheme relating to details of circuit arrangements for AC mains or AC distribution networks
- H02J2203/20—Simulating, e g planning, reliability check, modelling or computer assisted design [CAD]
Abstract
The invention discloses a kind of for the generalized impedance criterion calculation method of gird-connected inverter stability analysis and application.Establish the small signal impedance model of the small signal impedance model of the inverter side network port and the grid side network port under polar coordinates, according to the small signal impedance model of the inverter side network port established under polar coordinates and the small signal impedance model of the network port, calculate the generalized impedance for acquiring the inverter side network port and the grid side network port, two generalized impedances that second step obtains are divided by and obtain the ratio between the generalized impedance of the inverter side network port and the network port, as generalized impedance criterion.The generalized impedance criterion that the present invention obtains can be used for the small signal stabilization analysis of grid-connected inverter system, Conventional impedance method is solved the problems, such as because there is coupling due to impact analysis accuracy, it lays a good foundation to clear the power grid oscillation generated when extensive new energy accesses power grid, is the important method for designing circuit control device and improving stability.
Description
Technical field
The present invention relates to a kind of stabilization of power grids criterion calculation method and applications, more particularly, to a kind of for grid-connected inverse
Become the generalized impedance criterion calculation method and application of device stability analysis.
Background technique
With the development of electric system, more and more power electronic equipments start to be applied to electric system, including are used for
Gird-connected inverter, HVDC transmission system and the relevant application of flexible AC transmitting system of new energy access.Although electric power
Electronic equipment has the advantages that flexibly controllable, but the switching device of power electronic equipment can generate harmonic wave in power grid, harm electricity
Source quality and system are stablized.When new energy accesses power grid, in order to improve power delivery capabilities and save line cost, usually passing
Defeated route uses series capacitor compensation, but the interaction between series compensation capacitance and the control system of power electronic equipment
The sub-synchronous oscillation of power grid is may lead.Between the multiple dynamic devices of electric system, such as more Fans current transformers of wind field
Controller between interaction be also possible to lead to system oscillation unstability.
Nowadays the method for analysis system stability mainly has: time-domain-simulation method, characteristic value calculating method, complex torque coefficients,
Impedance method etc..Wherein, time-domain simulation method can directly observe the response curve of each state variable, it can be difficult to identifying each
The damping characteristic of oscillation mode, and required calculation amount is more huge, is not suitable for research large scale system；Characteristic value calculates
It can be concluded that the details about system oscillation, but when system complex, the solution of characteristic value becomes difficult；Multiple torque coefficient
Method is a simple and effective analysis method, but this method is only applicable to one machine infinity bus system, it is difficult to cope with multi-computer system
Complex oscillation；Impedance method is another easy analysis method, and this method is the gird-connected inverter table accessed for new energy
It is shown as the output impedance being connected on voltage source or current source.And utilize Nyquist criterion analysis power supply output impedance and network
The ratio between input impedance, to judge the stability of system.
The problem of Conventional impedance method, is, when impedance model is established under rest frame, deposits between positive-negative sequence impedance
It is coupling, ignoring coupling terms can make the judgement of system stability obtain the conclusion of mistake.When output impedance is under synchronous coordinate system
When modeling, equally exists and couple between the d axis and q axis of synchronous coordinate system.Therefore common Nyquist criterion can not still make
With.Although can analyze system stability using broad sense Nyquist criterion, analyze in this way it is complex, lose using resistance
The advantage of anti-method Simplified analysis.
Summary of the invention
The invention discloses a kind of for the generalized impedance criterion calculation method of gird-connected inverter stability analysis and application, benefit
Grid-connected inverter system stability is judged with Nyquist criterion and to analyze, referred to as generalized impedance method.
The technical solution adopted by the present invention is that there are three steps:
The first step establishes the small signal impedance model and the grid side network port of the inverter side network port under polar coordinates
Small signal impedance model；
Second step, according to the small signal impedance model and the network port of the inverter side network port established under polar coordinates
Small signal impedance model, calculate and acquire the generalized impedance of the inverter side network port and the grid side network port；
Two generalized impedances that second step obtains are divided by and obtain the inverter side network port and the network port by third step
The ratio between generalized impedance, as generalized impedance criterion.
The polar coordinates are using amplitude and phase angle as the polar coordinates of representation.
For the one machine infinity bus system that inverter and power grid form, the filter in inverter uses LCL filter, inverse
The control mode for becoming device adds bicyclic vector controlled using locking phase, and inverter meets following condition: the inner loop control of inverter has
The electric voltage feed forward and decoupling item of full remuneration, and consider the dynamic of electric voltage feed forward full remuneration and inverter inner ring and phaselocked loop,
Outer ring dynamic, the equivalent delay of PWM link and the filter inductance resistance of inverter and the line resistance of grid side network are ignored
Disregard.
The inverter side network includes the output inductor of inverter and inverter, the inverter side network-side
The small signal impedance model expression of mouth are as follows:
Wherein, △ I is the disturbance of network port current amplitude, and I is network port electric current stable state amplitude,For the network port
Current phase angle disturbance, △ U are network port voltage disturbance, and U is network port voltage stable state amplitude, and △ δ is network port voltage
Phase angle disturbance,For inverter side network port admittance matrix, YgIndicate the non-of inverter side network port admittance matrix
Neutral element, YgExpression formula are as follows:
Wherein, s is Laplace operator, GpllIt (s) is the transmission function of phaselocked loop, Gpll(s)=(Kppll+Kipll/ s)/s,
KppllFor the proportionality coefficient of PI link in phaselocked loop, KipllFor the integral coefficient of PI link in phaselocked loop, G2It (s) is current inner loop
The transmission function of PI controller, G2(s)=Kp2+Ki2/ s, Kp2For the proportionality coefficient of inner ring PI link, Ki2For inner ring PI link
Integral coefficient, LfFor the output inductor of inverter.
The grid side network port includes the filter capacitor C of inverter LCL filter1, include LCL filter grid side
The substitutional connection inductance L of inductance1With route series compensation capacitance.
The small signal impedance model of the grid side network port is first indicated with the loop equation of following formula:
Wherein, L indicates that the component type of inductance, C indicate that the component type of capacitor, k indicate the element number of grid side, j
Indicate that the node serial number of grid side, j=1 indicate that the node serial number of the grid side network port, j=2 indicate substitutional connection inductance L1
With route series compensation capacitance C2Between node, φjFor the power-factor angle of node j, YL(1,1)Indicate inductance L1With 1 phase of node
The admittance matrix of pass, YL(1,2)Indicate inductance L1 and the relevant admittance matrix of node 2, YC(1,1)Indicate capacitor C1It is related to node 1
Admittance matrix, YC(2,2)Indicate capacitor C2With the relevant admittance matrix of node 2；
YL(1,1)And YL(1,2)It is all made of following formula calculating:
YC(1,1)And YC(2,2)It is all made of following formula calculating:
Wherein, YL(k,j)Indicate inductance LkAdmittance matrix relevant with node j, YC(k,j)Indicate capacitor CkIt is relevant with node j
Admittance matrix, s are Laplace operator, and ω is system angular frequency, and L indicates that inductance class component, C indicate that capacitor class component, k indicate
The element number of grid side network, j indicate that the node serial number of grid side network, j=1 indicate that the node of the grid side network port is compiled
Number, j=2 indicates substitutional connection inductance L1With route series compensation capacitance C2Between node, φjFor the power factor of node j
Angle, L1Indicate that the substitutional connection inductance of the grid side network port, substitutional connection are grid side filter inductance and line inductance
Inductance and；
Utilize Y=(YL(1,1)+YC(1,1))-YL(1,2)(YL(2,2)+YC(2,2))-1YL(1,1)Simplify loop equation to eliminate internal section
Point, the grid side network port equation after eliminating internal node are following formula, and the small signal as the grid side network port
Impedance model:
Wherein, Y indicates the small signal admittance matrix of the grid side network port.
The small signal impedance model of the inverter side network port and the grid side network port is all made of following formula table
Show:
Wherein, a indicates that △ I is influenced by △ U, and b indicates that △ I is influenced by U △ δ, and c is indicatedIt is influenced by △ U, d
It indicatesIt is influenced by U △ δ；
Then the generalized impedance of two kinds of network ports is all made of following formula and acquires:
ZG=(ad-bc)/a
Wherein, ZGIndicate the generalized impedance of the network port.
Specifically, the generalized impedance calculation formula of the inverter side network port is as follows:
Specifically, the generalized impedance calculation formula of the grid side network port is as follows:
ZG_grid=(Y (1,1) Y (2,2)-Y (1,2) Y (2,1))/Y (1,1)
Wherein, Y (1,1) is the element of Y matrix the first row first row, and Y (1,2) is the element of Y matrix the first row secondary series,
Y (2,1) is the element of the second row of Y matrix first row, and Y (2,2) is the element of the second row of Y matrix secondary series.
The generalized impedance ZGInverse be generalized admittance YG, generalized impedance ZGWith generalized admittance YGRelationship be similar to
The relationship of Conventional impedance and admittance, generalized admittance YGDefinition in the following ways:
When network port current amplitude disturbance △ I is 0, the generalized admittance of the network port is current phase angle correlative
The ratio between with network port voltage phase angle correlative U △ δ, that is, meet:
In formula, I is network port electric current stable state amplitude, and U is network port voltage stable state amplitude, and △ I is network port electricity
Flow disturbance,For the disturbance of network port current phase angle, △ δ is the disturbance of network port voltage phase angle.
The generalized impedance criterion can be used to judge the stability of grid-connected inverter system.
The generalized impedance Z of the inverter side network port is finally calculated in the method for the present inventionG_invWith the grid side network port
Generalized impedance ZG_gridThe ratio between ZG_inv/ZG_gridFoundation or controller design as grid-connected inverter system judgement of stability
With reference to.The nyquist plot that specific implementation both can be drawn, by judging that the intersection point of nyquist plot and negative real axis is
It is no other than (- 1, j0) point or within obtain the whether stable result of grid-connected inverter system.
The beneficial effects of the present invention are:
The present invention calculates the stability that the generalized impedance criterion obtained can be used to judge grid-connected inverter system, for analyzing
Inverter model have decoupling characteristic, caused by avoiding Conventional impedance method due to ignoring the coupling terms in inverter model
Error improves the accuracy of analysis.
The present invention is that the power grid oscillation generated when clearing extensive new energy access power grid is laid a good foundation, and is to improve inversion
The important evidence of device controller stability.
Detailed description of the invention
Fig. 1 is the calculating of generalized impedance method and analysis flow chart diagram of the invention.
Fig. 2 is the inverter one machine infinity bus system structural block diagram of embodiment.
Fig. 3 be system by small interference when phasor diagram.
Fig. 4 be under different line lengths the ratio between generalized impedance of the inverter side network port and the grid side network port how
Qwest's curve.
Fig. 5 is the system voltage current waveform that line inductance size changes front and back under dq coordinate system.
Specific embodiment
The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.
It is as shown in Figure 1 using the embodiment and its process of the method for the present invention progress system stability judgement.
The first step establishes the small signal impedance model and the grid side network port of the inverter side network port under polar coordinates
Small signal impedance model；
Specific example as shown in connection with fig. 2 considers inverter one machine infinity bus system, and wherein filter uses typical LCL
The control strategy of filtering, inverter adds bicyclic vector controlled using the most common locking phase, and inverter meets following assumed condition:
Assuming that 1: the inner loop control of inverter has electric voltage feed forward and decoupling item, and considers that electric voltage feed forward is fully compensated.
Assuming that 2: considering the dynamic of inverter inner ring and phaselocked loop, the equivalent delay of the dynamic and PWM link of outer ring is neglected
Slightly disregard.
Assuming that 3: ignoring filter inductance resistance and line resistance.
The dynamic characteristic of the phaselocked loop of the inverter may be expressed as:
The state equation of inverter filtering inductance are as follows:
After the decoupling and feedforward factor that consider inner loop control, the dynamical equation of inner loop control device are as follows:
Wherein, s is Laplace operator；UsdAnd UsqThe respectively d of node that is connected with inverter of inverter filtering inductance
Shaft voltage and q shaft voltage；UsdrAnd UsqrThe respectively d shaft voltage reference value of node that is connected with inverter of inverter filtering inductance
With q shaft voltage reference value；UdAnd UqThe respectively d shaft voltage and q shaft voltage of the node that are connected with network of inverter filtering inductance；
IdAnd IqThe respectively d axis component and q axis component of inverter output current；IdrAnd IqrThe respectively d axis of inverter output current
Component reference value and q axis component reference value；ω is the system angular frequency obtained by phaselocked loop；Gpll(s)=(Kppll+Kipll/s)/s
For the transmission function of phaselocked loop；ω0For system fundametal compoment angular frequency；LfFor the inductance value of inverter side filter inductance；G2(s)
For the transmission function of current inner loop PI controller, G2(s)=Kp2+Ki2/s。
Fig. 3 show phasor diagram of the system by small interference when.As seen from the figure, xy seat synchronous with dq two is shared in the figure
Mark system, wherein xy coordinate system is with the synchronization angular frequency of grid sidesThe coordinate system of rotation, dq coordinate system are then with phaselocked loop frequency
Rotatable coordinate axis on the basis of rate ω；θpllFor the angle between dq coordinate system and xy coordinate system, size is by phaselocked loop according to inverse
Become the q shaft voltage U for the node that device filter inductance is connected with networkqIt determines；θIAnd θURespectively electric current and voltage are in dq coordinate system
Phase angle,It is respectively the phase angle of electric current and voltage in xy coordinate system with δ.
Formula (1)-(3) are linearized, the dynamical equation under inverter microvariations can be obtained:
(4)-(6) can be rewritten as dynamic under the inverter microvariations indicated under polar coordinates by phasor relation according to Fig.3,
State equation:
As can be seen from FIG. 2, the angular relationship in above formula meets:
△θU=△ δ-△ θpll (10)
Simultaneous (10) and (7), can be by △ θpllIt is indicated with △ δ are as follows:
Due to not considering the delay of PWM link, so that
Again by assuming 2, the oscillation that the present invention is paid close attention to is the oscillation of secondary/supersynchronous frequency range and inner ring bandwidth is much higher than outer ring,
Therefore it is believed that outer ring exports constant, i.e. △ IdrWith △ IqrIt is 0.Therefore, bringing formula (8) and (9) into formula (13) can obtain:
The substitution of angular relationship shown in (10)-(12) formula (14) can be obtained again:
In formula,
Formula (15) is the small signal impedance model of the inverter side network port under polar coordinates.
In the grid-connected typical circuit of single inverter shown in Fig. 2, network port circuit includes the output filtering of inverter
Capacitor C1, consider the effective transmission route inductance L after the net side inductance of filter1, route series compensation capacitance C2, Yi Jiwu
Poor bulk power grid.
Element both ends node serial number is respectively indicated with i, j, indicates element number with k, available, the inductance member of linearisation
Part state equation are as follows:
Remember φiFor the power-factor angle of i-th of node, then formula (16) may be expressed as: under polar coordinates
For convenient for writing, above formula can be denoted as:
ΔIk=YL(k,i)ΔUi-YL(k,j)ΔUj (18)
Wherein,
Similarly, the capacitance state equation of linearisation are as follows:
It is expressed as under polar coordinates:
For that (21) can be denoted as convenient for writing:
ΔIk=YC(k,i)ΔUi-YC(k,j)ΔUj (22)
Wherein,
It can be obtained further according to topological column network loop equation shown in Fig. 2:
Particularly, when inverter is filtered using pure inductance, Y in formulaC(1,1)It is 0, when route is without series compensation capacitance,
YC(2,2)It is 0.
It can be calculated, the small signal admittance matrix of the grid side network port are as follows:
Y=(YL(1,1)+YC(1,1))-YL(1,2)(YL(2,2)+YC(2,2))-1YL(1,1) (25)
The small signal impedance model of the grid side network port under polar coordinates are as follows:
Second step, according to the small signal impedance model and the network port of the inverter side network port established under polar coordinates
Small signal impedance model, calculate and acquire the generalized impedance of the inverter side network port and the grid side network port；
Define (generalized admittance YG): when port current amplitude disturbance △ I is 0, the generalized admittance of port is current phase angle
CorrelativeThe ratio between with port voltage phase angle correlative U △ δ, that is, meet:
Similar to the relationship of Conventional impedance and admittance, the inverse of generalized admittance is generalized impedance ZG。
In formula, I is stable state port current, and U is stable state port voltage, and △ I is port current disturbance,For port current
Phase angle disturbance, △ δ are the disturbance of port voltage phase angle.
If the small signal impedance model of polar coordinates lower port are as follows:
Then the generalized impedance of the port can acquire according to the following formula:
ZG=(ad-bc)/a (29)
It can according to the small signal impedance model of the inverter side network port under (29) and polar coordinates and the grid side network port
In the hope of the generalized impedance Z of the inverter side network portG_invAnd the generalized impedance Z of the grid side network portG_grid。
Two generalized impedances that second step obtains are divided by and obtain the inverter side network port and the network port by third step
The ratio between generalized impedance, as generalized impedance criterion.
Below with reference to specific example, illustrate application of the ratio between the generalized impedance in terms of system stability analysis.In order to make to ask
Topic simplifies, and the inverter considered in example assumes that DC voltage is constant, and assumes that inverter injects watt current I to power griddref
With reactive current Iqref；Inverter is filtered using pure inductance, and inverters parameter is as shown in table 1.In simulations, consider route
Inductance becomes 0.7pu from 0.35pu, to simulate the synchronised grids of access varying strength.
Table 1 emulates the parameter of inverter model used
Using the generalized impedance of the inverter side network port and the grid side network port, whether stable to system can make
Judgement.For the machine net reciprocal effect characteristic equation of the system, the broad sense of the inverter side network port and the grid side network port
The ratio between impedance is ZG_grid(s)/ZG_inv(s), it draws respectively when line inductance is 0.35pu and Nai Kui when 0.7pu corresponding to it
This Tequ line, as a result as shown in Figure 4.
As seen from the figure, the nyquist plot of open-loop transfer function Mid Frequency be approximately two rotate clockwise it is ellipse
Circle, and negative real axis is passed through clockwise.With the increase of line length, the intersection point positioned at nyquist plot and negative real axis can be to the left
It is mobile.When line inductance is 0.35pu, intersection point is located at (- 1, j0) point right side, and nyquist plot does not surround (- 1, j0) point,
Therefore system is stablized.When line inductance is 0.7pu, intersection point is located at (- 1, j0) point left side, and nyquist plot surrounds clockwise
2 circle of (- 1, j0) point.It means that there are the poles that two are located at right half plane for former closed-loop system characteristic equation, therefore work as route
Series connection additional inductor and after dying down, system is unstable.
The Digital Simulation carried out in MATLAB software demonstrates the ratio between generalized impedance having as system stability criterion
Effect property.Simulation model is built in MATLAB/SIMULINK software, and the sampling of control system and control frequency are in emulation
The frequency of 4kHz, SVPWM are 4kHz, simulation step length 5us.
In emulation, in t=5s, line inductance becomes 0.7pu from 0.35pu, indicates the increase of contact line length.It is sat in dq
Under mark system, the system voltage current waveform that line inductance size changes front and back is as shown in Figure 5.Found out by figure, in series connection additional electrical
Before sense, the oscillation of system gradually decays, and system is stablized.After series connection additional inductance, systems stay oscillation will not
Unstability has occurred in decaying, system.Comparison MATLAB simulation result and theoretical analysis result, the two are consistent.
Pass through above-mentioned simulated example, it can be seen that generalized impedance method proposed by the present invention can accurate analysis system it is steady
It is qualitative.Analytic process avoids Conventional impedance method because of the problem of ignoring coupling terms and impact analysis accuracy.In the present invention
Generalized impedance not only may determine that the stability of system than criterion, is also used as in inverter control system design, improves inverse
Become the foundation of device stability.The method achieve the analyses of the depression of order of system, have for the stability analysis of complication system important
Meaning.
Above-mentioned specific embodiment is used to illustrate the present invention, rather than limits the invention, of the invention
In spirit and scope of protection of the claims, to any modifications and changes that the present invention makes, protection model of the invention is both fallen within
It encloses.
Claims (5)
1. a kind of generalized impedance criterion calculation method for gird-connected inverter stability analysis, it is characterised in that mainly include following
Three steps:
The first step establishes the small of under polar coordinates the small signal impedance model of the inverter side network port and the grid side network port
Signal impedance model；
The inverter side network includes the output inductor of inverter and inverter, the inverter side network port
Small signal impedance model expression are as follows:
Wherein, △ I is the disturbance of network port current amplitude, and I is network port electric current stable state amplitude,For network port electric current phase
Angle disturbance, △ U are network port voltage disturbance, and U is network port voltage stable state amplitude, and △ δ is that network port voltage phase angle is disturbed
It is dynamic,For inverter side network port admittance matrix, YgIndicate the nonzero element of inverter side network port admittance matrix,
YgExpression formula are as follows:
Wherein, s is Laplace operator, GpllIt (s) is the transmission function of phaselocked loop, Gpll(s)=(Kppll+Kipll/ s)/s, Kppll
For the proportionality coefficient of PI link in phaselocked loop, KipllFor the integral coefficient of PI link in phaselocked loop, G2(s) it is controlled for current inner loop PI
The transmission function of device processed, G2(s)=Kp2+Ki2/ s, Kp2For the proportionality coefficient of inner ring PI link, Ki2For the integral of inner ring PI link
Coefficient, LfFor the output inductor of inverter；
The grid side network port includes the filter capacitor C of inverter LCL filter1, include LCL filter grid side inductance
Substitutional connection inductance L1With route series compensation capacitance C2；
The small signal impedance model of the grid side network port is first indicated with the loop equation of following formula:
Wherein, L indicates that the component type of inductance, C indicate that the component type of capacitor, k indicate that the element number of grid side, j indicate
The node serial number of grid side, j=1 indicate that the node serial number of the grid side network port, j=2 indicate substitutional connection inductance L1With line
Road series compensation capacitance C2Between node, φjFor the power-factor angle of node j, YL(1,1)Indicate inductance L1With the node of j=1
Relevant admittance matrix, YL(1,2)Indicate the relevant admittance matrix of node of inductance L1 and j=2, YC(1,1)Indicate capacitor C1And j=
The relevant admittance matrix of 1 node, YC(2,2)Indicate capacitor C2Admittance matrix relevant with the node of j=2；
YL(1,1)And YL(1,2)It is all made of following formula calculating:
YC(1,1)And YC(2,2)It is all made of following formula calculating:
Wherein, YL(k,j)Indicate inductance LkAdmittance matrix relevant with node j, YC(k,j)Indicate capacitor CkAdmittance relevant with node j
Matrix, s are Laplace operator, and ω is system angular frequency, and L indicates that inductance class component, C indicate that capacitor class component, k indicate power grid
The element number of side network, j indicate that the node serial number of grid side network, j=1 indicate the node serial number of the grid side network port, j
=2 indicate substitutional connection inductance L1With route series compensation capacitance C2Between node, φjFor the power-factor angle of node j, L1
Indicate that the substitutional connection inductance of the grid side network port, substitutional connection are the inductance of grid side filter inductance and line inductance
With；
Second step, according to the small of the small signal impedance model of the inverter side network port established under polar coordinates and the network port
Signal impedance model calculates the generalized impedance for acquiring the inverter side network port and the grid side network port；
The small signal impedance model of the inverter side network port and the grid side network port is all made of following formula expression:
Wherein, a indicates △ I by the affecting parameters of △ U, and b indicates △ I by the affecting parameters of U △ δ, and c is indicatedIt is influenced by △ U
Parameter, d are indicatedBy the affecting parameters of U △ δ；
Then the generalized impedance of two kinds of network ports is all made of following formula and acquires:
ZG=(ad-bc)/a
Wherein, ZGIndicate the generalized impedance of the network port；
The generalized impedance calculation formula of the inverter side network port is as follows:
The generalized impedance calculation formula of the grid side network port is as follows:
ZG_grid=(Y (1,1) Y (2,2)-Y (1,2) Y (2,1))/Y (1,1)
Wherein, Y (1,1) be Y matrix the first row first row element, Y (1,2) be Y matrix the first row secondary series element, Y (2,
It 1) is the element of the second row of Y matrix first row, Y (2,2) is the element of the second row of Y matrix secondary series；
Two generalized impedances that second step obtains are divided by and obtain the wide of the inverter side network port and the network port by third step
The ratio between adopted impedance, as generalized impedance criterion.
2. a kind of generalized impedance criterion calculation method for gird-connected inverter stability analysis according to claim 1,
Be characterized in that: the polar coordinates are using amplitude and phase angle as the polar coordinates of representation.
3. a kind of generalized impedance criterion calculation method for gird-connected inverter stability analysis according to claim 1,
Be characterized in that: for the one machine infinity bus system of inverter and power grid composition, the filter in inverter uses LCL filter,
The control mode of inverter adds bicyclic vector controlled using locking phase, and inverter meets following condition: the inner loop control tool of inverter
Have the electric voltage feed forward and decoupling item of full remuneration, and consider electric voltage feed forward be fully compensated and inverter inner ring and phaselocked loop it is dynamic
State, outer ring dynamic, the equivalent delay of PWM link and the filter inductance resistance of inverter and the line resistance of grid side network are neglected
Slightly disregard.
4. a kind of generalized impedance criterion calculation method for gird-connected inverter stability analysis according to claim 1,
It is characterized in that: the generalized impedance ZGInverse be generalized admittance YG, generalized admittance YGDefinition in the following ways:
When network port current amplitude disturbance △ I is 0, the generalized admittance of the network port is current phase angle correlativeWith net
The ratio between network port voltage phase angle correlative U △ δ meets:
In formula, I is network port electric current stable state amplitude, and U is network port voltage stable state amplitude, and △ I is that network port electric current is disturbed
It is dynamic,For the disturbance of network port current phase angle, △ δ is the disturbance of network port voltage phase angle.
5. the application for the generalized impedance criterion that -4 any the methods obtain according to claim 1, it is characterised in that: described is wide
Adopted impedance criterion can be used to judge the stability of grid-connected inverter system.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201610946122.9A CN106532685B (en) | 2016-10-26 | 2016-10-26 | For the generalized impedance criterion calculation method of gird-connected inverter stability analysis and application |
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