CN110071514A - A kind of consistency droop control method restored for power distribution and electric voltage frequency - Google Patents
A kind of consistency droop control method restored for power distribution and electric voltage frequency Download PDFInfo
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- CN110071514A CN110071514A CN201910401618.1A CN201910401618A CN110071514A CN 110071514 A CN110071514 A CN 110071514A CN 201910401618 A CN201910401618 A CN 201910401618A CN 110071514 A CN110071514 A CN 110071514A
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/24—Arrangements for preventing or reducing oscillations of power in networks
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
- H02J3/381—Dispersed generators
-
- 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
-
- 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
Abstract
The invention proposes a kind of consistency droop control methods restored for power distribution and electric voltage frequency, are used for isolated island micro-grid system, realize that accurate active and reactive power is shared, while keep frequency is restored and average voltage is kept to reach rated value.In the control program proposed, it is only necessary to neighborhood reactive power information is exchanged by using sparse low bandwidth communication networks, rather than active power is transmitted by the communication link in existing coherence method, the information of reactive power and frequency.Compared with the existing method based on consistency, transmits data and data postpone significant reduction, and the high reliability of system may be implemented.In addition, even if can also ensure that accurate active/reactive power is shared and electric voltage frequency restores in the case where loading the interference with feed line impedance in the case where communication delay.The simulation result of hardware in loop is finally given, the validity of proposed control program is demonstrated.
Description
Technical field
The invention belongs to the microgrid fields in electric system, are related to a kind of for power distribution and electric voltage frequency recovery
Consistency droop control method.
Background technique
In recent years, in the micro-capacitance sensor (Microgrid, MG) of isolated island formula mode, droop control method is widely used in foundation
System frequency and bus voltage, and in the case where not using important traffic simultaneously in distributed power generation (Distributed
Generation, DG) active power is shared between unit.However, in these methods, being drawn by traditional droop control method
Rise voltage and frequency departure be inevitable, and under the conditions of unequal feed line impedance reactive power share it is very poor.
In order to solve problems, typical secondary control strategy declines power grid commonly used in isolated island, and voltage and frequency retrieval are arrived
Rated value, to compensate the limitation of sagging mechanism.Although secondary control strategy can eliminate voltage and frequency departure, micro- electricity
Net central controller (microgrid central controller, MGCC) needs to connect each distribution DG unit, this meeting
Increase system complexity and reduces scalability and reliability.In recent years, MAS control theory obtains in MG system
Research extensively, and the main target of the control of the consistency based on multiple agent is realized between all agencies in a network
General protocol, this only needs the interaction closed between DG, this is higher compared with the focus control mode reliability based on MGCC.So
And at least side frequency, voltage, active power and reactive power information need to transmit in a communication network with equal for power
Point, in this case, high density data will lead to the challenge of data processing and the analysis of extensive micro-grid system.In addition,
Once there are biggish delays or communication link to break down in communication network, lack any desired data, whole system
It will be unstable.
It is learnt according to patent retrieval, Chinese invention patent 201611074223.8 provides a kind of voltage of isolated island micro-capacitance sensor
Uneven secondary control method.It is controlled by voltage of the secondary control to distributed generation resource, to the imbalance electricity of PCC point
Pressure is compensated, and realizes the zero steady state error control of electric current, voltage.This method is not only from the voltage of global angle compensation PCC point
Deviation, and realize the accurate distribution of reactive power.However, this method is not accounted for since sagging controlling mechanism is brought
Electric voltage frequency deviation.Chinese invention patent 201710979119.1 proposes empty in a kind of low pressure micro-capacitance sensor based on MAS
The distributed and coordinated control method of quasi- power supply includes a secondary control and secondary control, and a secondary control is based on virtual impedance and virtually
Power supply is used cooperatively, and it is idle respectively to improve micro- source to a certain extent.Secondary control is based on consistency protocol, passes through micro-capacitance sensor
Sparse communication network carry out the interaction of each virtual power supply information of voltage between micro- source, coordinate each virtual power supply voltage and reach stringent
Unanimously.But this method needs a large amount of data information of interaction between each DG, and communication link once breaks down or exists logical
Letter delay, the stability of micro-capacitance sensor are easy to be affected.
In conclusion existing common secondary control and consistency control can realize it is active/idle divide equally, but two
Secondary control often relies on central controller, increases the complexity of system and substantially reduces the reliability of system；And common consistency
Control then needs to interact highdensity data and is just able to achieve good control effect, if each DG unit interaction data prolongs
Shi Xianxiang will also result in the bad of control, furthermore existing consistency control method lacks sagging mechanism, the performance of multiple DG and be
The stability of system also will receive influence.Therefore, it is necessary to study a kind of power-sharing control methods of high reliability, and can be
It is realized in the case of the mutually not same complex electric network of line impedance and guarantees electric voltage frequency while accurate active/reactive power is divided equally
Maintain rated value.
Summary of the invention
It is an object of the invention to overcome in micro-capacitance sensor each distributed generation resource (DG) since line impedance difference and load are disturbed
Voltage/frequency offrating problem is eliminated while moving active/idle mean allocation in situation, is proposed a kind of for function
The consistency droop control method that rate distribution and electric voltage frequency restore, mentioned method combination consistency control algolithm and sagging control
The advantages of algorithm processed, guarantees that electric voltage frequency maintains rated value while realizing each DG power-sharing.
The specific technical proposal of the invention is: being directed to isolated island micro-grid system, propose a kind of for power distribution and voltage
The consistency droop control method of frequency retrieval specifically includes consistent with sagging control advantage in conjunction with common consistency algorithm
Property droop control device, it is shared to be able to achieve accurate active/reactive power, and the frequency of each DG is maintained at rated value and nothing
Need neighborhood voltage, frequency and active information.In addition, it is contemplated that the ability of DG unit, mentioned controller can be used for sharing idle function
Rate, while the average voltage of MG being adjusted to rated value；Voltage and current controller then guarantees the steady of each DG voltage electric current
It is qualitative.The control method proposed through the invention, it can be ensured that isolated island micro-capacitance sensor is multiple in line impedance difference and load disturbance etc.
Dividing equally for active/reactive power is realized under general labourer's condition, voltage and frequency retrieval enhance the fast of micro-grid system to rated value
Speed and stability
The present invention includes the following steps:
S1, the present invention indicate micro-capacitance sensor output voltage amplitude and operation using the following droop control technology without communication
Angular frequency and corresponding reactive power and active power relationship:
In formula Chinese style, EiAnd ωiThe respectively voltage magnitude and angular frequency of micro-capacitance sensor actual motion.Ei *And ωi *Respectively
The rated voltage amplitude of micro-capacitance sensor operation and specified angular frequency, miAnd niIt is frequency and the sagging coefficient of amplitude, P respectivelyiAnd QiPoint
It is not the average active power value and reactive power value of measurement.However, the voltage as caused by sagging control and frequency departure are not
It is evitable, and reactive power cannot be shared in the method.
And then introduce consistency algorithm and combine sagging control algolithm, it establishes achievable power distribution and electric voltage frequency is extensive
The expression of multiple consistency droop control device, equivalent consistency droop control device is as follows:
Wherein piIt is instantaneous active power, ωiAnd EiRepresent the frequency and amplitude of output voltage, ωhAnd ωcIt respectively indicates and changes
Into frequency controller upper and lower bound cutoff frequency, PiAnd QiIt is the average active power and reactive power of measurement respectively
Value. mi, kp, kiIt is postiive gain, ω with bi *And Ei *It is specified angular frequency and voltage, χ respectivelyiAnd χjIt is to consider DGiCapacity adds
Weight coefficient can be set as being equal to DGiSagging coefficient derivative.
The improved frequency droop controller as shown in (2) can be used for realizing that accurate active power is shared, and by each DG
Frequency be maintained at voltage and frequency information of the rated value without neighborhood DG.In addition, it is contemplated that the ability of DG unit, is based on
The reactive power controller of consistency can be used for respectively reactive power, while the average voltage of MG being adjusted to rated value.
S2, further carries out steady-state performance analysis to consistency droop control method.Reactive power is allocated as first
Further analysis, in the time domain, the consistent equation of reactive power/voltage can rewrite as follows:
By taking derivative of each DG unit output voltage relative to the time, the dynamic that reactive power unanimously controls can be indicated
Are as follows:
The derivative of output voltage is equal to zero when in view of stable state, can obtain following matrix:
The equal representing matrix of black matrix variable or vector for noticing overstriking in formulation process in the present invention, wherein drawing general
Lars matrix indicates that diagonal matrix K is defined as K=diag { k with L1,k2,..,kNAnd column vectorQ/ χ is expressed asWith Q χ-1=[Q1/χ1,Q2/χ2,…,QN/χN]T。
According to two Important Theorems in figure theory: 1. if a figureInclude a root node, then it represents that it, which has, generates
, wherein at least there is the directapath to other each nodes in tree.2. L is symmetrical positive semidefinite matrix, zero, which is one, has right spy
Levy vector1Simple eigenvalue, and and if only ifWhen with directed spanning tree, all nonzero eigenvalues all have positive reality
Portion, i.e. L1 n=0 n,1 T nL=0 T n.So being only X=k to the untrivialo solution of LX=01And k > 0, the solution of (5) are available such as
Under:
Q=k (χ)-11, k > 0 (6)
It follows that reactive power is divided equally can be realized by consistency droop control device.
S3, further adjusts the analysis for doing corresponding steady-state performance to average voltage.It considers1 T nL=0 T n, in (5) formula
By multiplied by1 T nK-1Equation below available:
Then (7) can simplify are as follows:
In addition, the output voltage of each DG unit can be write as:
It is noted that the average voltage of micro-capacitance sensor distribution wire is described as follows:
Therefore, in conjunction with (8)-(10), average voltage amplitude is writeable are as follows:
WhereinIt is initial electric amplitude, it can be according to practical application flexible modulation, i.e.,It is set as rated voltage amplitude, E*
And kiEqual to 1, average voltage is adjustable as:
It was therefore concluded that average voltage can be equal to rated value, such as shown in (12).
S4, further, divides equally active power and frequency retrieval does the analysis of corresponding steady-state performance.Each DG's has
Function power is adjusted by the frequency droop controller in consistency droop control device, the active and frequency information without neighborhood DG.It is logical
It crosses using the equivalence between the sagging control of consistency and secondary control, equation (2) can be rewritten as (13):
Wherein kp,ωiAnd ki,ωiIt is DGiPostiive gain, Δ ω is for frequency compensated control variable, and P is to pass through low pass
The average active power of filter measurement.
In addition, the matrix form of (13) can derive are as follows:
ω=ω*-mP+J(ω*-ω) (14)
Wherein J=diag { kpωi+kiωi/ s }, i ∈ [1, N], kpωiAnd kiωiIt is DGiPostiive gain.ω*=ω* 1, ω=
[ω1,ω2,…,ω N]T, m=diag { mi, P=[P1,P2…PN]T。
Under steady state conditions, a reactor, (14) can be rewritten as:
In formula, ωs,And PsRespectively indicate ω, ω*With the steady-state value of P, JpAnd JIIt is the proportionality coefficient and product of J respectively
Divide coefficient.In view of the time correlation part of (15) is equal to zero in stable state, can obtainKωIt is gain vector note
It anticipates and arrives, frequency is a global variable, can be by ensuring that active power is shared based on sagging mechanism.It is thereby achieved that
Active power is divided equally, while the frequency of any DG unit is maintained at rated value.
The beneficial effects of the present invention are:
If 1, realizing the power-sharing of isolated island MG system using existing consistency control strategy, needing to exchange each
Active information, reactive power information, voltage and the frequency information of DG unit, if lacking any one or logical of above- mentioned information
Believe that route disconnects, the power-sharing of system will will fail.It is proposed by the present invention a kind of for power distribution and electric voltage frequency recovery
Consistency droop control method only need the reactive power information between DG, power-sharing can be realized.There are a large amount of points
(the case where bulk information is exchanged between DG unit is needed) in the isolated island formula MG system of cloth power supply, the control proposed
Method can be effectively reduced system communication pressure, improve system reliability.
2, in the event of communication failure, under existing consistency control strategy, system cannot exchange between DG appoints
What information, naturally also can not achieve power-sharing.At identical conditions, although system cannot pass through the sagging control of consistency
It is shared that method realizes reactive power, but still it is shared that active power may be implemented.In addition, frequency remains to stablize in rated value, table
Bright system is not influenced by communication failure.
Detailed description of the invention
Fig. 1 is the DG element circuit structure in parallel of isolated island micro-capacitance sensor in the embodiment of the present invention.
Fig. 2 is isolated island micro-capacitance sensor using a kind of consistency droop control method restored for power distribution and electric voltage frequency
Control principle drawing.
Fig. 3 is the dynamic response effect picture of isolated island micro-capacitance sensor under the sagging control strategy of tradition.
Fig. 4 is the dynamic response effect picture that the sagging control strategy of consistency controls lower isolated island micro-capacitance sensor.
Fig. 5 is the dynamic response effect picture in the presence of isolated island micro-capacitance sensor under the sagging control strategy of consistency in the case of delay.
Specific embodiment
Elaborate with reference to the accompanying drawing to the embodiment of the present invention: the present embodiment before being with technical solution of the present invention
It puts and is implemented, the detailed implementation method and specific operation process are given, but protection scope of the present invention is not limited to down
The embodiment stated.
Fig. 1 is the DG element circuit structure in parallel of isolated island micro-capacitance sensor in the embodiment of the present invention, by 4 DG and 3 load groups
At being connected to micro-capacitance sensor, including line impedance, load unit and static switch by PCC point in each DG unit, wherein each
DG unit is made of the local controller of three-phase full-bridge inverter, LCL filter and DG unit.Additionally, it is contemplated that unequal
Feed line impedance and DG unit different rated power, the rated power of DG1 and DG2 are twice of DG3 and DG4 rated capacity,
Complete parameter provides in tablei.
Table I
The present invention includes the following steps:
S1, the present invention indicate micro-capacitance sensor output voltage amplitude and operation using the following droop control technology without communication
Angular frequency and corresponding reactive power and active power relationship:
In formula Chinese style, EiAnd ωiThe respectively voltage magnitude and angular frequency of micro-capacitance sensor actual motion.Ei *And ωi *Respectively
The rated voltage amplitude of micro-capacitance sensor operation and specified angular frequency, miAnd niIt is frequency and the sagging coefficient of amplitude, P respectivelyiAnd QiPoint
It is not the average active power value and reactive power value of measurement.However, the voltage as caused by sagging control and frequency departure are not
It is evitable, and reactive power cannot be shared in the method.Therefore, the invention proposes one kind for power distribution and
The sagging control program of consistency that electric voltage frequency restores, exists as shown in Fig. 2, wherein establishing including voltage and current controller
The interior MG inner ring based on VSI adjusts output voltage and electric current while keeping system stability.It can be seen that voltage control
The reference in circuit processed is generated by proposed consistency droop control device.
It due to the deficiency of droop control device, and then introduces consistency algorithm and combines sagging control algolithm, foundation can be real
The consistency droop control device that existing power distribution and electric voltage frequency restore, the expression of equivalent consistency droop control device
It is as follows:
Wherein piIt is instantaneous active power, ωiAnd EiRepresent the frequency and amplitude of output voltage, ωhAnd ωcIt respectively indicates and changes
Into frequency controller upper and lower bound cutoff frequency, PiAnd QiIt is the average active power and reactive power of measurement respectively
Value. mi, kp, kiIt is postiive gain, ω with bi *And Ei *It is specified angular frequency and voltage, χ respectivelyiAnd χjIt is to consider DGiCapacity adds
Weight coefficient can be set as being equal to DGiSagging coefficient derivative.
As shown in Fig. 2 and (2), shown improved frequency droop controller can be used for realizing that accurate active power is shared,
And the frequency of each DG is maintained at voltage and frequency information of the rated value without neighborhood DG.In addition, it is contemplated that DG unit
Ability, the reactive power controller based on consistency can be used for respectively reactive power, while the adjusting of the average voltage of MG being arrived
Rated value.
S2, further carries out steady-state performance analysis to consistency droop control method.Reactive power is allocated as first
Further analysis, in the time domain, the consistent equation of reactive power/voltage can rewrite as follows:
By taking derivative of each DG unit output voltage relative to the time, the dynamic that reactive power unanimously controls can be indicated
Are as follows:
The derivative of output voltage is equal to zero when in view of stable state, can obtain following matrix:
Wherein Laplacian Matrix is indicated with L, and diagonal matrix K is defined as K=diag { k1,k2,..,kNAnd column vector
Q/ χ is expressed asWith Q χ-1=[Q1/χ1,Q2/χ2,…,QN/χN]T。
According to two Important Theorems in figure theory: 1. if a figureInclude a root node, then it represents that it, which has, generates
, wherein at least there is the directapath to other each nodes in tree.2. L is symmetrical positive semidefinite matrix, zero, which is one, has right spy
Levy vector1Simple eigenvalue, and and if only ifWhen with directed spanning tree, all nonzero eigenvalues all have positive reality
Portion, i.e. L1 n=0 n,1 T nL=0 T n.So being only X=k to the untrivialo solution of LX=01And k > 0, the solution of (5) are available such as
Under:
Q=k (χ)-11, k > 0 (6)
It follows that reactive power is divided equally can be realized by consistency droop control device.
Further, the analysis for doing corresponding steady-state performance is adjusted to average voltage.It considers1 T nL=0 T n, lead in (5) formula
Cross multiplied by1 T nK-1Equation below available:
Then (7) can simplify are as follows:
In addition, the output voltage of each DG unit is writeable as follows:
It is noted that the average voltage of micro-capacitance sensor distribution wire is described as follows:
Therefore, in conjunction with (8)-(10), average voltage amplitude is writeable are as follows:
WhereinIt is initial voltage amplitude, it can be according to practical application flexible modulation, i.e.,It is set as rated voltage amplitude,
E*And kiEqual to 1, average voltage is adjustable as:
It was therefore concluded that average voltage can be equal to rated value, such as shown in (12).
Further, active power is divided equally and frequency retrieval does the analysis of corresponding steady-state performance.The wattful power of each DG
Rate is adjusted by the frequency droop controller in consistency droop control device, the active and frequency information without neighborhood DG.By making
With the equivalence between the sagging control of consistency and secondary control, equation (2) can be rewritten as (13):
Wherein kp,ωiAnd ki,ωiIt is DGiPostiive gain, Δ ω is for frequency compensated control variable, and P is to pass through low pass
The average active power of filter measurement.
In addition, the matrix form of (13) can derive are as follows:
ω=ω*-mP+J(ω*-ω) (14)
Wherein J=diag { kpωi+kiωi/ s }, i ∈ [1, N], kpωiAnd kiωiIt is DGiPostiive gain.ω*=ω* 1, ω=
[ω1,ω2,…,ω N]T, m=diag { mi, P=[P1,P2…PN]T。
Under steady state conditions, a reactor, (14) can be rewritten as:
In formula, ωs,And PsRespectively indicate ω, ω*With the steady-state value of P, JpAnd JIIt is the proportionality coefficient and product of J respectively
Divide coefficient.In view of the time correlation part of (15) is equal to zero in stable state, can obtainKωIt is gain vector.
It is noted that frequency is a global variable, it can be by ensuring that active power is shared based on sagging mechanism.Therefore, Ke Yishi
Existing active power is divided equally, while the frequency of any DG unit is maintained at rated value.
In order to verify accuracy of the sagging control strategy of proposed consistency under complex working condition, Fig. 3 and Fig. 4 are respectively
Dynamic response effect picture of the isolated island micro-capacitance sensor under the sagging control of tradition and under the sagging control strategy of consistency, Fig. 5 are to exist to prolong
When in the case of under the sagging control strategy of consistency isolated island micro-capacitance sensor dynamic response effect picture.(a) in Fig. 3, Fig. 4 and Fig. 5,
(b), (c) and (d) respectively indicates the active power of each DG of micro-capacitance sensor, reactive power.Voltage and frequency dynamic response condition.
After introduction based on above-mentioned Fig. 3, Fig. 4 and Fig. 5 service condition, separately below to the dynamic effect of Fig. 3, Fig. 4 and Fig. 5
It is described in detail.
As shown in Fig. 3 (a), initially load is connected to MG system, the stable state active power of each DG be respectively 1000W,
1000W, 500W and 500W.As t=1.5s, load 1 with MG system disconnect, the active power of each DG be down to respectively 750W,
750W, 380W and 380W.Maximum active power fluctuation is 30W or so, under feeder line and the disturbed condition of load, system energy
In shorter regulating time (about 0.3s) interior stable operation.In t=3.5s, load 1 is reconnected, in minor swing and minor
It saves in the time, active power is restored to normal value, shows that system can realize have under load disturbance by the sagging control of tradition
Function power is divided equally.However, due to the inherent shortcoming of the sagging control of tradition, as shown in Fig. 3 (b)-(d), under steady state conditions, a reactor,
Reactive power, voltage and frequency departure decline 31.527var, 0.913v and 0.158hz respectively, illustrate under the sagging control of tradition
Isolated island micro-capacitance sensor stability it is bad.
The dynamic response of the consistency droop control device of the bringing onto load disturbance proposed in the present invention is as shown in Figure 4.This
In the case of, active and reactive power can be divided in portion, while average voltage being adjusted to rated value, such as Fig. 4 (a) and
(b) shown in.It is noted that reactive power (being less than 15.517var) only has the dynamic of very little in the disturbance of feeder line and load
State fluctuation, as shown in Fig. 4 (b).It is recommended that single busbar voltage should be offset slightly from rated value (less than 5%), to realize that each DG is mono-
The accurate reactive power distribution of member.It is maximum when the respectively active and reactive power of isolated island formula MG system as shown in Fig. 4 (c)
Voltage difference is less than 0.09V (about the 0.15% of nominal power voltage amplitude).In addition, Fig. 4 (d) shows in no field DG unit
In the case where voltage and frequency information, frequency can be restored to rated value.Wave compared with Fig. 3 Traditional control strategy, in Fig. 4
It moves smaller (about 0.028Hz), regulating time is shorter (about 0.51s).
In addition, being investigated influence of the communication delay to the control method proposed, and sparse in the DG low bandwidth of system
It joined continuous 400 millisecond delay in communication network.Improved consistency droop control device is not by time delay
It influences, because the program does not need neighborhood active power, frequency and information of voltage.Therefore, in communication delay even communication system
In the case where collapse, accurate reactive power distribution and frequency retrieval may be implemented.It therefore, can from Fig. 5 (a) and 5 (d)
Out, the active power of system is divided equally and frequency retrieval is corresponding to the dynamic of not communication delay identical (such as Fig. 4 (a) and 4 (d)).
Although it can be seen that the about minor fluctuations of 0.2V or so of output voltage, (can be less than in a short time in Fig. 5 (c)
1s) it is adjusted.As shown in Fig. 5 (b), even if nor affecting on accurate reactive power distribution in the case where communication delay,
Reactive power allocation result and non-delay situation are essentially identical, show that the reliability of MG system is higher.
Those of ordinary skill in the art will understand that the embodiments described herein, which is to help reader, understands this hair
Bright principle, it should be understood that protection scope of the present invention is not limited to such specific embodiments and embodiments.This field
Those of ordinary skill disclosed the technical disclosures can make according to the present invention and various not depart from the other each of essence of the invention
The specific variations and combinations of kind, these variations and combinations are still within the scope of the present invention.
Claims (1)
1. a kind of consistency droop control method restored for power distribution and electric voltage frequency, which is characterized in that including as follows
Step:
S1, indicated using the following droop control technology without communication micro-capacitance sensor output voltage amplitude and operation angular frequency with it is right
The reactive power and active power relationship answered:
In formula Chinese style, EiAnd ωiThe respectively voltage magnitude and angular frequency of micro-capacitance sensor actual motion；Ei *And ωi *Respectively micro- electricity
Net the rated voltage amplitude run and specified angular frequency；miAnd niIt is frequency and the sagging coefficient of amplitude respectively；PiAnd QiIt is to survey respectively
The average active power value and reactive power value of amount；However, the voltage as caused by sagging control and frequency departure are inevitable
, and reactive power cannot be shared in the method；
And then introduce consistency algorithm and combine sagging control algolithm, it establishes and can be achieved what power distribution and electric voltage frequency restored
The expression of consistency droop control device, equivalent consistency droop control device is as follows:
Wherein piIt is instantaneous active power；ωiAnd EiRepresent the frequency and amplitude of output voltage；ωhAnd ωcIt respectively indicates improved
The upper and lower bound cutoff frequency of frequency controller；PiAnd QiIt is the average active power and reactive power value of measurement respectively；mi,
kp, kiIt is postiive gain with b；ωi *And Ei *It is specified angular frequency and voltage respectively；χiAnd χjIt is to consider DGiThe weighting coefficient of capacity,
It can be set as being equal to DGiSagging coefficient derivative；
The improved frequency droop controller as shown in (2) can be used for realizing that accurate active power is shared, and by the frequency of each DG
Rate is maintained at voltage and frequency information of the rated value without neighborhood DG；In addition, it is contemplated that the ability of DG unit, is based on consistency
Reactive power controller can be used for respectively reactive power, while the average voltage of MG being adjusted to rated value；
S2, further carries out steady-state performance analysis to consistency droop control method；Reactive power is allocated as into one first
Step analysis, in the time domain, the consistent equation of reactive power/voltage can rewrite as follows:
By taking derivative of each DG unit output voltage relative to the time, the dynamic that reactive power unanimously controls be may be expressed as:
The derivative of output voltage is equal to zero when in view of stable state, can obtain following matrix:
Notice the equal representing matrix of black matrix variable or vector of overstriking in formulation process in the present invention, wherein Laplce
Matrix indicates that diagonal matrix K is defined as K=diag { k with L1,k2,..,kNAnd column vectorQ/ χ is expressed asWith Q χ-1=[Q1/χ1,Q2/χ2,…,QN/χN]T；
According to two Important Theorems in figure theory: 1. if a figureIncluding a root node, then it represents that it has spanning tree,
Wherein at least there is the directapath to other each nodes；2. L is symmetrical positive semidefinite matrix；Zero be one have right feature to
Amount1Simple eigenvalue, and and if only ifWhen with directed spanning tree, all nonzero eigenvalues all have positive real part, i.e.,
L1 n=0 n,1 T nL=0 T n；So being only X=k to the untrivialo solution of L X=01And k > 0, the solution of (5) are available as follows:
Q=k (χ)-11, k > 0 (6)
It follows that reactive power is divided equally can be realized by consistency droop control device；
S3, further adjusts the analysis for doing corresponding steady-state performance to average voltage；It considers1 T nL=0 T n, pass through in (5) formula
Multiplied by1 T nK-1Equation below available:
Then (7) can simplify are as follows:
In addition, the output voltage of each DG unit is writeable as follows:
It is noted that the average voltage of micro-capacitance sensor distribution wire is described as follows:
Therefore, in conjunction with (8)-(10), average voltage amplitude is writeable are as follows:
Wherein Ei dIt is initial voltage amplitude, it can be according to practical application flexible modulation, i.e. Ei dIt is set as rated voltage amplitude, E*And ki
Equal to 1, average voltage is adjustable as:
It was therefore concluded that average voltage can be equal to rated value, such as shown in (12)；
S4, further, divides equally active power and frequency retrieval does the analysis of corresponding steady-state performance；The active power of each DG
It is adjusted by the frequency droop controller in consistency droop control device, the active and frequency information without neighborhood DG；By using
Equation (2) can be rewritten as (13) by the equivalence between the sagging control of consistency and secondary control:
Wherein kp,ωiAnd ki,ωiIt is DGiPostiive gain, Δ ω is for frequency compensated control variable, and P is to pass through low-pass filter
The average active power of measurement；
In addition, the matrix form of (13) can derive are as follows:
ω=ω*-mP+J(ω*-ω) (14)
Wherein J=diag { kpωi+kiωi/ s }, i ∈ [1, N], kpωiAnd kiωiIt is DGiPostiive gain；ω*=ω* 1, ω=[ω1,
ω2,…,ωN]T, m=diag { mi, P=[P1,P2…PN]T；
Under steady state conditions, a reactor, (14) can be rewritten as:
ωs=ωs,*-nPs+Jp(ωs,*-ωs)+JI(ωs,*-ωs)(t-t0)+Kω(t0) (15)
In formula, ωs, ωs,*And PsRespectively indicate ω, ω*With the steady-state value of P；JpAnd JIIt is the proportionality coefficient and integration system of J respectively
Number, KωIt is gain vector；In view of the time correlation part of (15) is equal to zero in stable state, ω can be obtaineds=ωs,*；Pay attention to
It arrives, frequency is a global variable, can be by ensuring that active power is divided equally based on sagging mechanism；It is thereby achieved that having
Function power is shared, while the frequency of any DG unit is maintained at rated value.
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