CN106786805B - A kind of straight trend section coordination method for optimally controlling of friendship counted and photovoltaic cluster accesses - Google Patents
A kind of straight trend section coordination method for optimally controlling of friendship counted and photovoltaic cluster accesses Download PDFInfo
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- 239000011159 matrix material Substances 0.000 claims description 13
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Classifications
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
- H02J3/46—Controlling of the sharing of output between the generators, converters, or transformers
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/04—Circuit arrangements for ac mains or ac distribution networks for connecting networks of the same frequency but supplied from different sources
- H02J3/06—Controlling transfer of power between connected networks; Controlling sharing of load between connected 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
- H02J3/24—Arrangements for preventing or reducing oscillations of power in networks
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- H02J3/383—
-
- 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]
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/50—Photovoltaic [PV] energy
- Y02E10/56—Power conversion systems, e.g. maximum power point trackers
Abstract
A kind of straight trend section coordination method for optimally controlling of friendship counted and photovoltaic cluster accesses: insertion switch function, based on separate unit inverter and the straight trend section mathematical model of the friendship of nonlinear characteristic, dynamic expanding method and coordinate transform, establish by the straight trend section mathematical model of the friendship of the more inverters meter constituted and nonlinear characteristic；Power coordination optimal controller is constructed, realizes the Primary regulation of the reasonable distribution and DC bus-bar voltage of handing over straight trend section transimission power；It constructs voltage and restores optimal controller, recovery control is carried out to DC bus-bar voltage, realizes the Secondary Control to DC bus-bar voltage, and improve the dynamic response characteristic of DC bus-bar voltage.The present invention can quickly stabilize power swing, maintain alternating current-direct current mixing microgrid internal power balance；While realizing the coordinated control to more parallel running inverters, and it can guarantee that each inverter has optimal dynamic response characteristic；Not only it can guarantee zero dy namics asymptotically stability, but also be able to achieve inverter dynamic characteristic optimum control.
Description
Technical field
Straight trend control of section method is handed over the present invention relates to a kind of.More particularly to a kind of meter and the friendship of photovoltaic cluster access
Straight trend section coordinates method for optimally controlling.
Background technique
With the continuous development of new-energy grid-connected technology, more and more renewable energy access power grid.Photovoltaic, wind-powered electricity generation etc.
It will make network trend that there is randomness and uncertainty after intermittent energy is grid-connected, especially when the intermittent energy such as photovoltaic
When source is grid-connected in the form of cluster, it will so that larger range fluctuation occurs in network trend, it will the difficulty of aggravation system load flow control
Degree.
Micro-capacitance sensor has obtained extensive as a kind of effective way for making bulk power grid more efficiently receive new energy
Concern.Nowadays, specific gravity friendship growing day by day, traditional shared by the ratio of the new energy such as photovoltaic access power distribution network and DC load
Stream micro-capacitance sensor is difficult to preferably adapt to the access of high density distributed energy.Alternating current-direct current mixing micro-capacitance sensor taken into account AC microgrids and
The advantages of direct-current micro-grid, can make up for it the deficiency of conventional AC microgrid.Alternating current-direct current mixing micro-capacitance sensor can reduce energy multi-level and turn
Loss in changing can more fully consider the output characteristics of the photovoltaic distributed energy, more efficiently balanced to consider direct current
The power demand of load and AC load, thus preferably realize distributed energy cluster access under " source-net-lotus-storage " it is excellent
Change operation and coordinated control.
Alternating current-direct current mixing micro-capacitance sensor includes to exchange sub- microgrid and the sub- microgrid of direct current, passes through AC/DC between the sub- microgrid of alternating current-direct current
Bi-directional inverter connection, the transregional transmission of mixing microgrid internal power is realized by AC/DC bi-directional inverter.More parallel runnings
AC/DC bi-directional inverter constitute and hand over straight trend section.In order to realize real-time, the dynamic of alternating current-direct current mixing microgrid internal power
Balance, stabilizes photovoltaic cluster access bring power swing, and the power for needing to study more bi-directional inverters on trend section is soft
Property control technology.By the coordinated control of the bi-directional inverter to more paired runnings, realize that stable state transmits function on trend section
The reasonable distribution of rate, dynamic response is optimal in transient process.
Summary of the invention
The technical problem to be solved by the invention is to provide under a kind of consideration photovoltaic cluster access conditions, realize to hand over straight tide
The straight trend section of friendship of flow section transmitting active power coordinated allocation, the optimal meter of dynamic response and the access of photovoltaic cluster is coordinated most
Excellent control method.
The technical scheme adopted by the invention is that: a kind of optimal control of the straight trend section coordination of friendship counted and photovoltaic cluster accesses
Method processed, includes the following steps:
1) insertion switch function, based on separate unit inverter and the straight trend section mathematical model of the friendship of nonlinear characteristic,
Dynamic expanding method and coordinate transform are established by the straight trend section mathematics of the friendship of the more inverters meter constituted and nonlinear characteristic
Model；
2) power coordination optimal controller is constructed, realizes the reasonable distribution and DC bus for handing over straight trend section transimission power
The Primary regulation of voltage；
3) building voltage restores optimal controller, carries out recovery control to DC bus-bar voltage, realizes to DC bus electricity
The Secondary Control of pressure, and improve the dynamic response characteristic of DC bus-bar voltage.
Step 1) specifically includes:
(1) under x coordinate space, the straight trend section mathematical model of the friendship of meter and nonlinear characteristic to separate unit inverter into
Mobile state expansion, the straight trend section mathematical model of the friendship of the meter and nonlinear characteristic that obtain inverter is as follows, and subscript k is indicated in formula
Kth platform inverter:
Wherein:
Wherein, each symbol definition is as follows: id(k)、iq(k)Represent the dq axis component of kth platform inverter ac-side current；
id_ref(k)、iq_ref(k)Represent the reference value of kth platform inverter ac-side current dq axis component；ed、eqRepresent alternating current net side three-phase
The dq axis component of voltage, ξ1(k)、ξ2(k)It is the dynamic state variables introduced, L(k)Kth platform inverter exchange side filter inductance is represented,
ω is the angular frequency of power grid, ud(k)、uq(k)Represent the dq axis component of kth platform inverter exchange side voltage；
(2) coordinate transform is chosen, by the straight trend section number of the friendship of the meter of the inverter after dynamic expanding and nonlinear characteristic
It learns model to be mapped under the space new coordinate system z, obtains the new inverter under z coordinate space after state feedback linearization
The straight trend section mathematical model of friendship of meter and nonlinear characteristic；It is specific:
Based on differential geometric theory, following dynamic expanding coordinate transform is chosen:
z(k)=Φ(k)(x) it is mapped for the coordinate under from x coordinate space to z coordinate space, wherein Φ(k)(x) micro- for part
Divide homeomorphism,
The Bu Lunuofu that the straight trend section mathematical model of the friendship of the meter of separate unit inverter and nonlinear characteristic is written as follow
This base master pattern, the straight trend section mathematical model of the friendship of the meter and nonlinear characteristic that constitute new separate unit inverter:
Wherein:
V is the straight trend section mathematical model of friendship of the meter and nonlinear characteristic of separate unit inverter new under z coordinate space
Input variable, i.e. pre-control variable；
(3) specific as follows by the straight trend section mathematical model of the friendship of the n platform inverter meter constituted and nonlinear characteristic:
Wherein:
A(k)And B(k)For the square in the straight trend section mathematical model of friendship of the meter and nonlinear characteristic of new separate unit inverter
Battle array.
Step 2) includes:
(1) the sagging control law of adaptively coordination of active power and DC bus-bar voltage is established, specific as follows:
△P(k)=m(k)×△udc (5)
Wherein, each symbol definition is as follows: △ udc=udc_ref-udcRepresent DC bus-bar voltage departure, udcRepresent direct current
The measuring value of busbar voltage；udc_refRepresent the reference value of DC bus-bar voltage, △ P(k)Represent the difference power that each inverter undertakes
Volume, m(k)For the sagging coefficient of each inverter；
The sagging coefficient of each inverter is defined as follows:
Wherein:
△P(k)max=2PN(k) (8)
Each symbol definition is as follows: PN(k)Represent the rated power of inverter transmission, Pre(k)Represent the dynamic power of inverter
Allowance, P(k)For actual measurement inverter transmit active power, it is specified that from exchanging area to DC area transmission be to be positive, udcmax、
udcminRespectively DC bus-bar voltage upper limit value and lower limit value, △ udcmax、△P(k)maxRespectively represent DC bus-bar voltage and kth
The maximum deviation of platform inverter transimission power；
(2) using feedback linearization method improve transimission power dynamic response characteristic, be according to feedback linearization method,
The straight trend section mathematical model of friendship of meter and nonlinear characteristic to separate unit inverter new obtained in step 1) seeks inner ring
Feedback Control Laws obtain:
v(k)Indicate pre-control variable, u(k)Indicate input variable.
Wherein:
Pre-control variable v is sought by quadratic performance index linear optimal contro8 design method(k):
Wherein P* is the solution of following Riccati equation:
R and Q is respectively the weight matrix of input variable and state variable, A(k)And B(k)For separate unit new obtained in step 1)
Matrix in the straight trend section mathematical model of friendship of the meter and nonlinear characteristic of inverter.
Building voltage described in step 3) restores optimal controller, comprising:
The meter of inverter and the straight trend section mathematics of the friendship of nonlinear characteristic after the dynamic expanding according to obtained in step 1)
Model chooses output vector again are as follows:
Choose following coordinate transform:
Wherein ξ is to eliminate steady-state error and the expansion dynamic variable that introduces, ξ(k)=∫ z '4(k)dt；
The straight trend section mathematical model of friendship of meter and nonlinear characteristic to separate unit inverter new obtained in step 1),
Inner loop feedback control law is sought, control variable u ' is obtained(k)
Wherein:
Wherein, each symbol definition is as follows: C represents DC bus equivalent capacitance, id(k)、iq(k)Represent the exchange of kth platform inverter
The dq axis component of side electric current；iq_ref(k)Represent the reference value of kth platform inverter ac-side current q axis component, udc_ref(k)Represent
The reference value of k platform inverter DC bus-bar voltage,；ed、eqRepresent the dq axis component of alternating current net side three-phase voltage, L(k)Represent kth
Platform inverter exchanges side filter inductance, and ω is the angular frequency of power grid, ILRepresent kth platform Converter DC-side output current value.
Pre-control variable v ' is sought by quadratic performance index linear optimal contro8 design method(k):
Wherein P* is the solution of following Riccati equation:
R and Q is respectively the weight matrix of input variable and state variable, A(k)And B(k)For separate unit new obtained in step 1)
Matrix in the straight trend section mathematical model of friendship of the meter and nonlinear characteristic of inverter.
A kind of straight trend section of friendship of of the invention meter and photovoltaic cluster access coordinates method for optimally controlling, and have has as follows
Beneficial effect:
(1) the mentioned control method of the present invention can fully consider the access of photovoltaic cluster to micro-capacitance sensor power flowcontrol bring shadow
It rings, can quickly stabilize power swing, maintain alternating current-direct current mixing microgrid internal power balance, improve DC bus-bar voltage quality；
(2) power coordination distribution and dynamic response optimal dual excellent when the mentioned control method of the present invention can take into account stable state
Change target, while realizing the coordinated control to more parallel running inverters, and it is optimal to can guarantee that each inverter has
Dynamic response characteristic；
(3) present invention fully considers the nonlinear characteristic of trend section, using the method for dynamic expanding to system zero dy namics
It is designed.Theoretical and case verification was the result shows that mentioned method not only can guarantee zero dy namics asymptotically stability, but also be able to achieve inverter
Dynamic characteristic optimum control.
Detailed description of the invention
Fig. 1 is the flow chart of the straight trend section coordination method for optimally controlling of friendship of present invention meter and the access of photovoltaic cluster；
Fig. 2 is photovoltaic cluster access mixing microgrid exemplary topology diagram；
Fig. 3 is system entirety control block diagram；
Fig. 4 is NONLINEAR OPTIMAL CONTROL block diagram；
Fig. 5 is adaptively to coordinate sagging rule curve graph；
Fig. 6 is DC bus-bar voltage waveform diagram；
Fig. 7 is trend section transimission power waveform diagram；
Fig. 8 is DC bus-bar voltage waveform diagram in voltage recovery process；
Fig. 9 is transimission power waveform diagram under Traditional control in voltage recovery process；
Figure 10 is transimission power waveform diagram under NONLINEAR OPTIMAL CONTROL in voltage recovery process.
Specific embodiment
Coordinate below with reference to friendship straight trend section of the embodiment and attached drawing to a kind of meter of the invention and the access of photovoltaic cluster
Method for optimally controlling is described in detail.
As shown in Figure 1, a kind of meter of the invention and the straight trend section of friendship of photovoltaic cluster access coordinate method for optimally controlling,
Include the following steps:
1) consider the characteristic of the switch non-linearity of inverter, insertion switch function is based on separate unit inverter and non-thread
Property characteristic the straight trend section mathematical model of friendship, dynamic expanding method and coordinate transform, establish the meter that is made of more inverters
And the straight trend section mathematical model of friendship of nonlinear characteristic；It specifically includes:
(1) under x coordinate space, the straight trend section mathematical model of the friendship of meter and nonlinear characteristic to separate unit inverter into
Mobile state expansion, the straight trend section mathematical model of the friendship of the meter and nonlinear characteristic that obtain inverter is as follows, and subscript k is indicated in formula
Kth platform inverter:
Wherein:
Wherein, each symbol definition is as follows: id(k)、iq(k)Represent the dq axis component of kth platform inverter ac-side current；
id_ref(k)、iq_ref(k)Represent the reference value of kth platform inverter ac-side current dq axis component；ed、eqRepresent alternating current net side three-phase
The dq axis component of voltage, ξ1(k)、ξ2(k)It is the dynamic state variables introduced, L(k)Kth platform inverter exchange side filter inductance is represented,
ω is the angular frequency of power grid, ud(k)、uq(k)Represent the dq axis component of kth platform inverter exchange side voltage；
(2) coordinate transform is chosen, by the straight trend section number of the friendship of the meter of the inverter after dynamic expanding and nonlinear characteristic
It learns model to be mapped under the space new coordinate system z, obtains the new inverter under z coordinate space after state feedback linearization
The straight trend section mathematical model of friendship of meter and nonlinear characteristic；It is specific:
Based on differential geometric theory, following dynamic expanding coordinate transform is chosen:
z(k)=Φ(k)(x) it is mapped for the coordinate under from x coordinate space to z coordinate space, wherein Φ(k)(x) micro- for part
Divide homeomorphism,
The Bu Lunuofu that the straight trend section mathematical model of the friendship of the meter of separate unit inverter and nonlinear characteristic is written as follow
This base master pattern, the straight trend section mathematical model of the friendship of the meter and nonlinear characteristic that constitute new separate unit inverter:
Wherein:
v(k)For the meter of separate unit inverter new under z coordinate space and the straight trend section mathematical model of the friendship of nonlinear characteristic
Input variable, i.e. pre-control variable；
(3) specific as follows by the straight trend section mathematical model of the friendship of the n platform inverter meter constituted and nonlinear characteristic:
Wherein:
A(k)And B(k)For the square in the straight trend section mathematical model of friendship of the meter and nonlinear characteristic of new separate unit inverter
Battle array.
2) power coordination optimal controller is constructed, realizes the reasonable distribution and DC bus for handing over straight trend section transimission power
The Primary regulation of voltage, specific control block diagram are as shown in Figure 3 and Figure 4；Include:
(1) the sagging control law of adaptively coordination of active power and DC bus-bar voltage is established, it be according to each inverter
Dynamic margin adaptively change sagging coefficient, and then guarantee that power difference coordinates optimum allocation between more inverters.
It is specific as follows:
△P(k)=m(k)×△udc (5)
Wherein, each symbol definition is as follows: △ udc=udc_ref-udcRepresent DC bus-bar voltage departure, udcRepresent direct current
The measuring value of busbar voltage；udc_refRepresent the reference value of DC bus-bar voltage, △ P(k)Represent the difference power that each inverter undertakes
Volume, m(k)For the sagging coefficient of each inverter；
The sagging coefficient of each inverter is defined as follows:
Wherein:
△P(k)max=2PN(k) (8)
Each symbol definition is as follows: PN(k)Represent the rated power of inverter transmission, Pre(k)Represent the dynamic power of inverter
Allowance, P(k)For actual measurement inverter transmit active power, it is specified that from exchanging area to DC area transmission be to be positive, udcmax、
udcminRespectively DC bus-bar voltage upper limit value and lower limit value, △ udcmax、△P(k)maxRespectively represent DC bus-bar voltage and kth
The maximum deviation of platform inverter transimission power；
The sagging control law curve of the adaptively coordination of active power and DC bus-bar voltage is as shown in Figure 5.Wherein,
a)△udc> 0, DC bus-bar voltage is lower than voltage rating, illustrates for DC area, the wattful power that system issues
Rate is less than the active power that system absorbs, and exchanging area should be by bi-directional inverter to DC area transmission power, that is, △ P at this time(k)>
0；
b)△udc< 0, DC bus-bar voltage is higher than voltage rating, illustrates for DC area, the wattful power that system issues
Rate is greater than the active power that system absorbs, and DC area should be to the power that exchanging area conveys surplus by bi-directional inverter at this time
△P(k)<0。
(2) dynamic response characteristic for improving transimission power using feedback linearization method, is that it exists as controller inner ring
It realizes to outer ring reference instruction quickly, while accurately track, devise explicit state feedback optimal control, it is super to reduce transimission power
It adjusts, so that oscillation is decayed as early as possible, improve the dynamic response of transimission power.
According to feedback linearization method, the friendship of meter and nonlinear characteristic to separate unit inverter new obtained in step 1)
Straight trend section mathematical model seeks inner loop feedback control law, obtains:
v(k)Indicate pre-control variable, u(k)Indicate input variable,
Wherein:
Pre-control variable v is sought by quadratic performance index linear optimal contro8 design method(k):
Wherein P* is the solution of following Riccati equation:
R and Q is respectively the weight matrix of input variable and state variable, A(k)And B(k)For separate unit new obtained in step 1)
Matrix in the straight trend section mathematical model of friendship of the meter and nonlinear characteristic of inverter.
3) building voltage restores optimal controller, carries out recovery control to DC bus-bar voltage, realizes to DC bus electricity
The Secondary Control of pressure, and improve the dynamic response characteristic of DC bus-bar voltage.Specific control block diagram is as shown in Figure 3 and Figure 4.Its
In, the building voltage restores optimal controller, comprising:
The meter of inverter and the straight trend section mathematics of the friendship of nonlinear characteristic after the dynamic expanding according to obtained in step 1)
Model chooses output vector again are as follows:
Choose following coordinate transform:
Wherein ξ is to eliminate steady-state error and the expansion dynamic variable that introduces, ξ(k)=∫ z '4(k)dt；
The straight trend section mathematical model of friendship of meter and nonlinear characteristic to separate unit inverter new obtained in step 1),
Inner loop feedback control law is sought, control variable u ' is obtained(k)
Wherein:
Wherein, each symbol definition is as follows: C represents DC bus equivalent capacitance, id(k)、iq(k)Represent the exchange of kth platform inverter
The dq axis component of side electric current；iq_ref(k)Represent the reference value of kth platform inverter ac-side current q axis component, udc_ref(k)Represent
The reference value of k platform inverter DC bus-bar voltage,；ed、eqRepresent the dq axis component of alternating current net side three-phase voltage, L(k)Represent kth
Platform inverter exchanges side filter inductance, and ω is the angular frequency of power grid, ILRepresent kth platform Converter DC-side output current value.
Pre-control variable v ' is sought by quadratic performance index linear optimal contro8 design method(k):
Wherein P* is the solution of following Riccati equation:
R and Q is respectively the weight matrix of input variable and state variable, A(k)And B(k)For separate unit new obtained in step 1)
Matrix in the straight trend section mathematical model of friendship of the meter and nonlinear characteristic of inverter.
Embodiment is given below.
Under alternating current-direct current mixing microgrid structure shown in Fig. 2, related embodiment is provided.Wherein, parameters are as follows: exchange
Network voltage 10kV, transformer voltage ratio 10kV/220V, ac filter inductance 81.136mH, DC bus voltage rating 560V are changed
Flow device switching frequency 3000Hz.
Embodiment 1: when systematic steady state is run to 0.6s, direct-current micro-grid sudden load increase 280kW, when operation is to 0.8s, direct current
Microgrid load is die-offed 480kW.DC bus-bar voltage waveform and trend section transimission power waveform difference are as shown in Figure 6 and Figure 7.
As seen from Figure 6, when step disturbance occurs for DC load, mentioned control strategy is able to maintain that DC bus electricity
Pressure is stablized, and DC bus-bar voltage is made to have linear dynamic response, and the dynamic regulation time is short, dead-beat.
As seen from Figure 7, after step disturbance occurs for load, each inverter transmitting active power changes therewith
Become, to make up power difference, realizes the dynamic equilibrium of power.When 0.6s sudden load increase, lateral DC side transmission wattful power is exchanged
Rate increases, and the power difference that the active power allowance of three inverters is successively successively decreased, thus undertaken also is sequentially reduced, wherein No. 1
Inverter undertakes 110kW, and No. 2 inverters undertake 92.5kW, and No. 3 inverters undertake 70kW；When 0.8s load is die-offed, direct current is lateral
It exchanges side transmitting active power to increase, the active power allowance power difference incremented by successively, thus undertaking of three inverters
It successively increases, wherein No. 1 inverter undertakes 147.5kW, No. 2 inverters undertake 157.5kW, and No. 3 inverters undertake 170kW.?
In transient process, each inverter transimission power non-overshoot, dead-beat, regulating time is short, embodies good dynamic response characteristic.
Embodiment 2: when system stable operation is to 0.7s, DC load is uprushed 500kW, and MEMS issues instruction when 0.8s, is opened
Dynamic voltage restores control.This paper voltage is restored into optimum control and traditional constant voltage control strategy compares, under two kinds of strategies
DC bus-bar voltage waveform is as shown in figure 8, hand over straight trend section transmitting active power difference as shown in Figure 9 and Figure 10.
As seen from Figure 8, mentioned voltage restores optimum control and can effectively improve dynamic voltage characteristics herein, so that
There is no overshoot in voltage recovery process, there is shorter regulating time, thus it is controlled compared to traditional constant voltage with more excellent
Dynamic response characteristic.
Comparison diagram 9 and Figure 10 can be seen that since the margin of power of No. 1 inverter after 0.7s is maximum, thus MEMS is cut
It changes No. 1 inverter and undertakes the task that voltage restores control.When using this paper control strategy, in transient process, inverter transmits function
Rate is small without impact, overshoot, and oscillation can comparatively fast calm down, and regulating time is short, has more preferably power dynamic response characteristic.
Claims (4)
1. a kind of meter and the straight trend section of friendship of photovoltaic cluster access coordinate method for optimally controlling, which is characterized in that including as follows
Step:
1) insertion switch function, based on separate unit inverter and the straight trend section mathematical model of the friendship of nonlinear characteristic, dynamic
Expansion method and coordinate transform are established by the straight trend section mathematical modulo of the friendship of the more inverters meter constituted and nonlinear characteristic
Type；
2) power coordination optimal controller is constructed, realizes the reasonable distribution and DC bus-bar voltage for handing over straight trend section transimission power
Primary regulation；
3) building voltage restores optimal controller, carries out recovery control to DC bus-bar voltage, realizes to DC bus-bar voltage
Secondary Control, and improve the dynamic response characteristic of DC bus-bar voltage.
2. a kind of meter according to claim 1 and the straight trend section of friendship of photovoltaic cluster access coordinate method for optimally controlling,
It is characterized in that, step 1) specifically includes:
(1) under x coordinate space, the straight trend section mathematical model of the friendship of meter and nonlinear characteristic to separate unit inverter is moved
State expansion, the straight trend section mathematical model of the friendship of the meter and nonlinear characteristic that obtain inverter is as follows, and subscript k indicates kth in formula
Platform inverter:
Wherein:
Wherein, each symbol definition is as follows: id(k)、iq(k)Represent the dq axis component of kth platform inverter ac-side current；id_ref(k)、
iq_ref(k)Represent the reference value of kth platform inverter ac-side current dq axis component；ed、eqRepresent the dq of alternating current net side three-phase voltage
Axis component, ξ1(k)、ξ2(k)It is the dynamic state variables introduced, L(k)Kth platform inverter exchange side filter inductance is represented, ω is power grid
Angular frequency, ud(k)、uq(k)Represent the dq axis component of kth platform inverter exchange side voltage；
(2) coordinate transform is chosen, by the straight trend section mathematical modulo of the friendship of the meter of the inverter after dynamic expanding and nonlinear characteristic
Type is mapped under the space new coordinate system z, obtain the new inverter under z coordinate space after state feedback linearization meter and
The straight trend section mathematical model of the friendship of nonlinear characteristic；It is specific:
Based on differential geometric theory, following dynamic expanding coordinate transform is chosen:
z(k)=Φ(k)(x) it is mapped for the coordinate under from x coordinate space to z coordinate space, wherein Φ(k)(x) same for infinitesimal
Embryo,
The Bu Lunuo Paderewski that the straight trend section mathematical model of the friendship of the meter of separate unit inverter and nonlinear characteristic is written as follow
Master pattern, the straight trend section mathematical model of the friendship of the meter and nonlinear characteristic that constitute new separate unit inverter:
Wherein:
V is the input of the straight trend section mathematical model of friendship of the meter and nonlinear characteristic of separate unit inverter new under z coordinate space
Variable, i.e. pre-control variable；
(3) specific as follows by the straight trend section mathematical model of the friendship of the n platform inverter meter constituted and nonlinear characteristic:
Wherein:
A(k)And B(k)For the matrix in the straight trend section mathematical model of friendship of the meter and nonlinear characteristic of new separate unit inverter.
3. a kind of meter according to claim 2 and the straight trend section of friendship of photovoltaic cluster access coordinate method for optimally controlling,
It is characterized in that, step 2) includes:
(1) the sagging control law of adaptively coordination of active power and DC bus-bar voltage is established, specific as follows:
ΔP(k)=m(k)×Δudc (5)
Wherein, each symbol definition is as follows: Δ udc=udc_ref-udcRepresent DC bus-bar voltage departure, udcRepresent DC bus
The measuring value of voltage；udc_refRepresent the reference value of DC bus-bar voltage, Δ P(k)The power difference that each inverter undertakes is represented,
m(k)For the sagging coefficient of each inverter；
The sagging coefficient of each inverter is defined as follows:
Wherein:
ΔP(k)max=2PN(k) (8)
Each symbol definition is as follows: PN(k)Represent the rated power of inverter transmission, Pre(k)The dynamic power allowance of inverter is represented,
P(k)For actual measurement inverter transmit active power, it is specified that from exchanging area to DC area transmission be to be positive, udcmax、udcminRespectively
For DC bus-bar voltage upper limit value and lower limit value, Δ udcmax、ΔP(k)maxRespectively represent DC bus-bar voltage and kth platform inverter
The maximum deviation of transimission power；
(2) dynamic response characteristic for improving transimission power using feedback linearization method, is according to feedback linearization method, to step
It is rapid 1) obtained in the straight trend section mathematical model of friendship of meter and nonlinear characteristic of new separate unit inverter seek inner loop feedback
Control law obtains:
v(k)Indicate pre-control variable, u(k)Indicate input variable；
Wherein:
In formula, ω is the angular frequency of power grid；id(k)、iq(k)Represent the dq axis component of kth platform inverter ac-side current；ed、eqGeneration
The dq axis component of table alternating current net side three-phase voltage；L(k)Represent kth platform inverter exchange side filter inductance；
Pre-control variable v is sought by quadratic performance index linear optimal contro8 design method(k):
Wherein P* is the solution of following Riccati equation:
R and Q is respectively the weight matrix of input variable and state variable, A(k)And B(k)For the separate unit change of current new obtained in step 1)
Matrix in the straight trend section mathematical model of friendship of the meter and nonlinear characteristic of device.
4. a kind of meter according to claim 2 and the straight trend section of friendship of photovoltaic cluster access coordinate method for optimally controlling,
It is characterized in that, building voltage described in step 3) restores optimal controller, comprising:
The meter of inverter and the straight trend section mathematical model of the friendship of nonlinear characteristic after the dynamic expanding according to obtained in step 1),
Again output vector is chosen are as follows:
Choose following coordinate transform:
Wherein ξ is to eliminate steady-state error and the expansion dynamic variable that introduces, ξ(k)=∫ z '4(k)dt；
The straight trend section mathematical model of friendship of meter and nonlinear characteristic to separate unit inverter new obtained in step 1), seeks
Inner loop feedback control law obtains control variable u '(k)
Wherein:
Wherein, each symbol definition is as follows: C represents DC bus equivalent capacitance, id(k)、iq(k)Represent kth platform inverter exchange side electricity
The dq axis component of stream；iq_ref(k)Represent the reference value of kth platform inverter ac-side current q axis component, udc_ref(k)Represent kth platform
The reference value of inverter DC bus-bar voltage；ed、eqRepresent the dq axis component of alternating current net side three-phase voltage, L(k)Kth platform is represented to change
It flows device and exchanges side filter inductance, ω is the angular frequency of power grid, ILRepresent kth platform Converter DC-side output current value；
Pre-control variable v ' is sought by quadratic performance index linear optimal contro8 design method(k):
Wherein P* is the solution of following Riccati equation:
R and Q is respectively the weight matrix of input variable and state variable, A(k)And B(k)For the separate unit change of current new obtained in step 1)
Matrix in the straight trend section mathematical model of friendship of the meter and nonlinear characteristic of device.
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