CN116614019B - Bandwidth improving method under direct-current voltage stabilizing framework of bidirectional charging pile virtual synchronous machine - Google Patents
Bandwidth improving method under direct-current voltage stabilizing framework of bidirectional charging pile virtual synchronous machine Download PDFInfo
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Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
- B60L53/00—Methods of charging batteries, specially adapted for electric vehicles; Charging stations or on-board charging equipment therefor; Exchange of energy storage elements in electric vehicles
- B60L53/60—Monitoring or controlling charging stations
- B60L53/62—Monitoring or controlling charging stations in response to charging parameters, e.g. current, voltage or electrical charge
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
- B60L53/00—Methods of charging batteries, specially adapted for electric vehicles; Charging stations or on-board charging equipment therefor; Exchange of energy storage elements in electric vehicles
- B60L53/30—Constructional details of charging stations
- B60L53/31—Charging columns specially adapted for electric vehicles
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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
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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
- H02J3/40—Synchronising a generator for connection to a network or to another generator
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/66—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output with possibility of reversal
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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]
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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
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/60—Other road transportation technologies with climate change mitigation effect
- Y02T10/70—Energy storage systems for electromobility, e.g. batteries
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- Charge And Discharge Circuits For Batteries Or The Like (AREA)
Abstract
The invention relates to the technical field of bidirectional charging piles of electric automobiles, in particular to a bandwidth lifting method under a direct current voltage stabilizing framework of a virtual synchronous machine of a bidirectional charging pile, which is used for solving the problem that the virtual synchronous machine of the bidirectional charging pile cannot meet the control requirement of a direct current voltage control outer ring of the virtual synchronous machine of the bidirectional charging pile under low dynamic response due to insufficient bandwidth of an active control ring of the virtual synchronous machine of the bidirectional charging pile in the prior art, and comprises the following steps: acquiring a small signal model of an active control loop of a virtual synchronous machine of the bidirectional charging pile; and according to the small signal model, reducing the closed loop transfer function between the power command and the output power by using forward channel filtering and parallel feedforward, so as to improve the bandwidth of an active control loop in the bidirectional charging pile virtual synchronous machine. The invention improves the active control loop bandwidth of the virtual synchronous machine of the bidirectional charging pile, effectively improves the dynamic tracking capability of direct-current voltage, and improves the stability of the voltage of the middle direct-current bus of the bidirectional charging pile.
Description
Technical Field
The invention relates to the technical field of bidirectional charging piles of electric automobiles, in particular to a bandwidth lifting method under a direct-current voltage stabilizing framework of a virtual synchronous machine of a bidirectional charging pile.
Background
An important mode of interaction of the bidirectional charging pile and the vehicle network of the electric vehicle is to operate as a virtual synchronous machine of the bidirectional charging pile,as a distributed power source to provide inertial support for the grid and further participate in the frequency modulation of the grid. Referring to fig. 1, a typical control architecture for the operation of the bi-directional charging pile virtual synchronous machine in the prior art is to use a current transformer to stabilize the voltage of the intermediate DC bus, and DC/DC to accurately track the charging and discharging power. Under the control architecture, the DC/DC closed-loop control of the charging power of the power battery is realized, and a layer of DC voltage control outer ring is added to the bidirectional charging pile virtual synchronous machine (VSG) to control the capacitor C dc Direct current voltage U at both ends dc Is stable. However, the bidirectional charging pile virtual synchronous machine is used as an inner ring of the direct-current voltage control outer ring, the dynamic response speed is extremely slow, and the direct-current voltage control outer ring inputs a power instruction P of the VSG active control ring when the charging power is changed ref During abrupt change, the bidirectional charging pile virtual synchronous machine cannot track P rapidly ref The voltage of the intermediate DC bus cannot be stabilized due to the breakdown of the DC voltage, and the problem that the control requirement of the DC voltage control outer ring on the DC voltage cannot be met. If voltage stabilization is to be achieved, this can only be done at the cost of a large amount of dc bus capacitance. Further, P in FIG. 1 out For the output active power of VSG, Q is the output reactive power of VSG reactive control loop, Q ref To output reactive power reference value, K * Is the gain of the integral controller, i 0 Is used for the direct-current bus current,for charging instruction->Is a direct-current voltage reference value, D q Sag factor, V, of VSG reactive control loop 0 For the reference voltage amplitude of the power grid, V out The output voltage amplitude for the VSG reactive control loop.
Specifically, the bandwidth of the active control loop of the bi-directional charging pile virtual synchronous machine can affect the voltage stabilization of the intermediate dc bus voltage. However, the virtual inertia in the bidirectional charging pile virtual synchronous machine can reduce the system bandwidth, and as an inner ring, the low bandwidth of the bidirectional charging pile virtual synchronous machine can introduce delay in a direct-current voltage control outer ring and deteriorate dynamic response capability, so that voltage stabilization of an intermediate direct-current bus cannot be realized. Therefore, in the prior art, the bidirectional charging pile virtual synchronous machine ring and the direct current voltage control outer ring are mutually nested, so that the bandwidth of the bidirectional charging pile virtual synchronous machine cannot be improved under the condition that virtual inertia is not changed, and the problem that the control requirement of the bidirectional charging pile virtual synchronous machine bidirectional charging pile direct current voltage control outer ring cannot be met under the condition of low dynamic response of the bidirectional charging pile virtual synchronous machine caused by insufficient bandwidth of the active control ring of the bidirectional charging pile virtual synchronous machine cannot be solved.
Disclosure of Invention
Aiming at the defects in the prior art, the invention provides a bandwidth lifting method under a direct-current voltage stabilizing framework of a virtual synchronous machine of a bidirectional charging pile.
In order to achieve the above purpose, the method for improving the bandwidth under the direct current voltage stabilizing framework of the bidirectional charging pile virtual synchronous machine provided by the invention comprises the following steps: acquiring a small signal model of an active control loop of a virtual synchronous machine of the bidirectional charging pile; according to the small signal model, forward channel filtering and parallel feedforward are used for reducing a closed loop transfer function between a power instruction and output power; and reducing the order of the closed loop transfer function, so that the bandwidth of an active control loop in the bidirectional charging pile virtual synchronous machine is improved. According to the invention, the inherent oscillation pole of the bidirectional charging pile virtual synchronous machine is eliminated, so that the response speed and bandwidth of an active control loop of the bidirectional charging pile virtual synchronous machine are improved, the inner loop delay of a direct-current voltage control outer loop is reduced, and the dynamic tracking capability of direct-current voltage is effectively improved, thereby improving the stability of the middle direct-current bus voltage of the bidirectional charging pile and meeting the control requirement of the bidirectional charging pile direct-current voltage control outer loop of the bidirectional charging pile virtual synchronous machine.
Optionally, it is characterized in that:
the small signal model comprises a controller and a power transmission model;
the closed loop transfer function satisfies the following relationship:
wherein G is powe For the closed loop transfer function, ΔP is the output power of the active control loop of the virtual synchronous machine of the bidirectional charging pile, and ΔP ref The power command of the active control loop of the bidirectional charging pile virtual synchronous machine is represented by s which is a Lawster transformation operator, G 1 G is the transfer function of the controller 2 Is a transfer function of the power transfer model.
Optionally, the transfer function of the controller satisfies the following relationship:
wherein G is 1 J is virtual inertia, omega, which is the transfer function of the controller 0 Fundamental angular frequency of grid voltage, s is Lawster transformation operator, D p Is the sag factor.
Optionally, the transfer function of the power transfer model satisfies the following relationship:
wherein G is 2 E is the output voltage of the active control loop of the virtual synchronous machine of the bidirectional charging pile, U g For the grid voltage, X g Is the fundamental wave impedance of the power grid.
Optionally, the reducing the closed loop transfer function between the power command and the output power using forward channel filtering and parallel feed forward according to the small signal model includes the steps of:
a low-pass filter is added in a power forward channel of an active control loop in the bidirectional charging pile virtual synchronous machine;
adding a parallel feedforward path consisting of a high-pass filter and a gain link in an active control loop of the bidirectional charging pile virtual synchronous machine;
and eliminating an inherent oscillation pole in an active control loop of the bidirectional charging pile virtual synchronous machine by using the low-pass filter and the parallel feed-forward circuit, and further reducing the closed loop transfer function to be first order.
The method has the advantages that the inherent oscillation pole in the active control loop of the virtual synchronous machine of the bidirectional charging pile is eliminated by utilizing the low-pass filter and the parallel feed-forward circuit, so that the closed-loop transfer function is converted into a form of the low-pass filter, parameters in the low-pass filter and virtual inertia are completely decoupled, and the bandwidth of the active control loop of the virtual synchronous machine of the bidirectional charging pile can be conveniently adjusted at any time according to the requirement.
Optionally, the transfer function of the low pass filter satisfies the following relationship:
wherein G is 3 And s is a Lawster transformation operator, and m is a parameter.
Optionally, the transfer function of the high-pass filter satisfies the following relationship:
wherein G is 4 And s is a Lawster transformation operator, and m is a parameter.
Optionally, the transfer function of the gain element satisfies the following relationship:
wherein K is the transfer function of the gain link, m is a parameter, G 2 Is a transfer function of the power transfer model.
Optionally, the high pass filter and the gain element are connected in series.
Optionally, the low-pass filter and the controller are connected in series and then connected in parallel with the parallel feed-forward circuit.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the embodiments will be briefly described below, it being understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered limiting in scope, and that other related drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram of a typical control architecture for operation of a bi-directional charging pile virtual synchronous machine in the prior art;
fig. 2 is a flow chart of a bandwidth improving method under a direct current voltage stabilizing architecture of a bidirectional charging pile virtual synchronous machine according to an embodiment of the present invention;
fig. 3 is a schematic diagram of a small signal model of an active control loop of a virtual synchronous machine of a bidirectional charging pile, which is a direct-current voltage control outer loop according to an embodiment of the present invention;
FIG. 4 is a schematic diagram of forward channel filtering and parallel feed forward in accordance with an embodiment of the present invention;
fig. 5 is a prior art closed loop transfer function bode plot for power command tracking using the present invention.
Wherein: the device comprises a 1-direct current voltage control outer ring, a 2-controller, a 3-power transmission model, a 4-low-pass filter, a 5-parallel feedforward path, a 6-high-pass filter and a 7-gain link.
Detailed Description
Specific embodiments of the invention will be described in detail below, it being noted that the embodiments described herein are for illustration only and are not intended to limit the invention. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be apparent to one of ordinary skill in the art that: no such specific details are necessary to practice the invention. In other instances, well-known circuits, software, or methods have not been described in detail in order not to obscure the invention.
Throughout the specification, references to "one embodiment," "an embodiment," "one example," or "an example" mean: a particular feature, structure, or characteristic described in connection with the embodiment or example is included within at least one embodiment of the invention. Thus, the appearances of the phrases "in one embodiment," "in an embodiment," "one example," or "an example" in various places throughout this specification are not necessarily all referring to the same embodiment or example. Furthermore, the particular features, structures, or characteristics may be combined in any suitable combination and/or sub-combination in one or more embodiments or examples. Moreover, those of ordinary skill in the art will appreciate that the illustrations provided herein are for illustrative purposes and that the illustrations are not necessarily drawn to scale.
It should be noted in advance that in an alternative embodiment, the same symbols or alphabet meaning and number are the same as those present in all formulas, except where separate descriptions are made.
In an alternative embodiment, referring to fig. 2, the present invention provides a bandwidth improving method under a dc voltage stabilizing architecture of a virtual synchronous machine of a bidirectional charging pile, the method includes the following steps:
s1, acquiring a small signal model of an active control loop of the bidirectional charging pile virtual synchronous machine.
Specifically, in this embodiment, please refer to fig. 3, in which U dc Is a direct current voltage, namely the middle direct current bus voltage of the bidirectional charging pile,is a direct-current voltage reference value omega g And inputting the angular frequency of the signal for the grid-connected point. The small signal model comprises a controller 2 and a power transmission model 3, and a closed loop transfer function between a power instruction and output power of the small signal model can be obtained according to the small signal model, wherein the closed loop transfer function meets the following relation:
wherein G is power As a closed loop transfer function, delta P is the output power of the active control loop of the virtual synchronous machine of the bidirectional charging pile, delta P ref Power command for active control loop of virtual synchronous machine of bidirectional charging pile, s is Lawster transform operator, G 1 G is the transfer function of the controller 2 Is the transfer function of the power transfer model.
The transfer function of the controller and the transfer function of the power transfer model satisfy the following relationships:
wherein J is virtual inertia, ω 0 Is the fundamental wave angular frequency of the power grid voltage, D p Is a sagging coefficient; wherein E is the output voltage of the active control loop of the virtual synchronous machine of the bidirectional charging pile, U g For the grid voltage, X g Is the fundamental wave impedance of the power grid.
Further, in order to more clearly show how to boost the bandwidth of the active control loop of the bidirectional charging pile virtual synchronous machine, fig. 3 also shows the dc voltage control outer loop 1 of the bidirectional charging pile virtual synchronous machine simply, and the power command Δp ref Namely, the output of the dc voltage control outer ring, wherein PI is a PI controller of the dc voltage control outer ring, and the specific structure of the dc voltage control outer ring 1 can refer to the prior art, and will not be described herein.
S2, according to the small signal model, forward channel filtering and parallel feedforward are used for reducing a closed loop transfer function between a power command and output power.
Wherein, step S2 further comprises the following steps:
s21, a low-pass filter is added in a power forward channel of an active control loop in the bidirectional charging pile virtual synchronous machine.
Specifically, in this embodiment, referring to fig. 4, except for the dc voltage control outer ring 1, the rest of fig. 4 forms a new active control ring of the bidirectional charging pile virtual synchronous machine, the low-pass filter 4 is located in a power forward channel of the active control ring of the bidirectional charging pile virtual synchronous machine, that is, between the dc voltage control outer ring 1 and the controller 2, and the transfer function of the low-pass filter 4 satisfies the following relationship:
wherein G is 3 Is the transfer function of the low pass filter 4 and m is a parameter. The method has the advantages that the cut-off frequency of the low-pass filter 4, namely the parameter m, is convenient to adjust, provides preconditions for changing the bandwidth of the active control loop of the virtual synchronous machine of the bidirectional charging pile at any time according to the requirement, and simultaneously provides a basis for reducing the closed loop transfer function.
S22, adding a parallel feedforward path consisting of a high-pass filter and a gain link in an active control loop of the bidirectional charging pile virtual synchronous machine.
Specifically, in this embodiment, referring to fig. 4, the parallel feedforward path 5 includes a high-pass filter 6 and a gain link 7, the high-pass filter 6 and the gain link 7 are connected in series, the low-pass filter 4 and the controller 2 are connected in series and then connected in parallel with the parallel feedforward path 5, and the transfer function of the high-pass filter 6 satisfies the following relationship:
wherein G is 4 Is the transfer function of the high pass filter 6.
The parallel feedforward path 5 and the low-pass filter 4 are combined to change the closed-loop transfer function between the power command and the output power, and provide a basis for the reduction of the closed-loop transfer function.
S23, eliminating an inherent oscillation pole in the active control loop of the two-way charging pile virtual synchronous machine by utilizing the low-pass filter and the parallel feed-forward circuit, and further reducing the closed loop transfer function to be first order.
Specifically, in the present embodiment, according to the relational expression provided in step S1, it cannot be derived that:
it is not difficult to derive from this relation that the closed loop transfer function has two poles, i.e. the system is a second order system, since the bandwidth of the control system is mainly determined by the pole-zero of the closed loop transfer function, and the bandwidth of the control system is determined by the cut-off frequency of the system, and the second oscillation pole point existing in the second order system will affect the cut-off frequency of the second order system, reducing the bandwidth of the active control loop of the virtual synchronous machine of the bidirectional charging pile, further introducing delay in the outer loop 1 of the direct voltage control and deteriorating the dynamic tracking capability of the direct voltage, so that the virtual synchronous machine of the bidirectional charging pile is in low dynamic response and cannot meet the control requirement of the outer loop of the direct voltage control of the bidirectional charging pile of the virtual synchronous machine of the bidirectional charging pile.
Further, according to steps S21 and S22, after adding the low pass filter 4 and the parallel feed forward path 5, the closed loop transfer function between the power command and the output power will become:
G power2 adding a low-pass filter 4 and a closed loop transfer function after a parallel feedforward path 5 to an active control loop of the bidirectional charging pile virtual synchronous machine; k is the transfer function of the gain element 7 and is also the feed-forward channel coefficient of the feed-forward channel 6.
Further, it can be seen that about G power Is a third-order system with three closed loop poles:
wherein the closed loop pole s 1 The closed loop pole s is dependent only on the parameter m, i.e. the cut-off frequency of the low pass filter 4 2，3 Is a pair of conjugate poles and is related to parameters such as virtual inertia, droop coefficient and the like.
Meanwhile, the three-order system has two zero points:
wherein zero point s 4，5 Is related to the virtual inertia, sag factor, fundamental angular frequency of the grid voltage and transfer function K.
To make zero point s 4，5 Elimination of conjugate pole s 2，3 The third-order system is reduced to the first order, and s 1 Becomes the dominant pole, then K needs to satisfy the following relationship:
at this time, zero point s 4，5 The conjugate pole s can be eliminated 2，3 The third-order system is reduced to the first order, and the closed loop transfer function G is equivalently realized powe Reducing to a first order system, and closing loop transfer function G after reducing power2 Will become the following form:
wherein G is power As a closed loop transfer function G power In the form after the reduction, as can be seen from the relational expression, when the feedforward channel coefficient K meets the condition, the closed loop transfer function of the third-order system realizes the cancellation of the polar zero point. Closed loop transfer function G power2 Is transformed into a form of a low-pass filter, which is equivalent to a closed-loop transfer function G power1 Is transformed into the form of a low-pass filter and has a closed-loop transfer function G power1 Only the cut-off frequency m of the low-pass filter 4, independently of the parameters of the controller 2 and of the power transmission model 3. The parameter m can be adjusted at any time as the cut-off frequency of the low-pass filter 4, so that the parameter m can be adjusted in real time according to actual needs, and the bandwidth of the active control loop of the bidirectional charging pile virtual synchronous machine can be adjusted.
S3, reducing the closed loop transfer function, and further improving the bandwidth of an active control loop in the bidirectional charging pile virtual synchronous machine.
Specifically, in this embodiment, according to step S2, the closed loop transfer function between the power command and the output power of the active control loop of the bidirectional charging pile virtual synchronous machine is reduced from the second-order system to the first-order system through the low-pass filter 4 and the parallel feedforward path 5, so that the phase delay of the system is reduced, and the response speed and bandwidth of the active control loop of the bidirectional charging pile virtual synchronous machine are improved.
More specifically, the bandwidth of the active control loop of the bidirectional charging pile virtual synchronous machine is the bandwidth of a closed loop transfer function tracked by a power instruction, and the bandwidth of the closed loop transfer function is the frequency corresponding to the time when the amplitude-frequency characteristic curve of the closed loop transfer function passes through-3 dB. Referring to FIG. 5, a closed loop transfer function G of the prior art power1 About 2.12Hz, and the closed loop transfer function G after using the invention power3 Is about 7.93Hz, compared with the closed loop transfer function G po The bandwidth of the (c) is greatly improved. In addition, the value of the parameter m is completely decoupled from the virtual inertia J, so that the bandwidth of the active control loop of the bidirectional charging pile virtual synchronous machine can be independently set, and if the parameter m is larger, the active control loop of the bidirectional charging pile virtual synchronous machine has higher bandwidth, which is more beneficial to the voltage tracking of the direct-current voltage control outer loop, thereby improving the stability of the intermediate direct-current bus voltage of the bidirectional charging pile.
Furthermore, in the actual implementation process, the bandwidth of the active control loop of the bidirectional charging pile virtual synchronous machine can be improved by 10 times.
It should be noted that, in some cases, the actions described in the specification may be performed in a different order and still achieve desirable results, and in this embodiment, the order of steps is merely provided to make the embodiment more clear, and it is convenient to describe the embodiment without limiting it.
In summary, the method for eliminating the inherent oscillation pole in the active control loop of the bidirectional charging pile virtual synchronous machine by introducing the low-pass filter and the parallel feed-forward circuit into the active control loop of the bidirectional charging pile virtual synchronous machine is equivalent to reducing the closed loop transfer function of the active control loop of the bidirectional charging pile virtual synchronous machine from a second-order system to a first-order system, so that the delay of the inner loop of the active control loop of the bidirectional charging pile virtual synchronous machine, namely the direct-current voltage control outer loop, is greatly reduced, the response speed and the bandwidth of the active control loop of the bidirectional charging pile virtual synchronous machine are remarkably improved, the dynamic performance of the bidirectional charging pile virtual synchronous machine and the dynamic tracking capability of the direct-current voltage are effectively improved, the stability of the middle direct-current bus voltage of the bidirectional charging pile is improved, and the control requirement of the direct-current voltage control outer loop of the bidirectional charging pile virtual synchronous machine is further met.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention, and not for limiting the same; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the invention, and are intended to be included within the scope of the appended claims and description.
Claims (5)
1. The bandwidth lifting method of the bidirectional charging pile virtual synchronous machine under the direct current voltage stabilizing framework is characterized by comprising the following steps of:
the method comprises the steps of obtaining a small signal model of an active control loop of a bidirectional charging pile virtual synchronous machine, wherein the small signal model comprises a controller and a power transmission model, and transfer functions of the controller and the power transmission model respectively meet the following relations:
wherein G is 1 J is virtual inertia, omega, which is the transfer function of the controller 0 Fundamental angular frequency of grid voltage, s is Lawster transformation operator, D p For sag factor, G 2 E is the output voltage of the active control loop of the virtual synchronous machine of the bidirectional charging pile, U g For the grid voltage, X g Is the fundamental wave impedance of the power grid;
a low-pass filter is added in a power forward channel of an active control loop in the bidirectional charging pile virtual synchronous machine;
a parallel feedforward path consisting of a high-pass filter and a gain link is added in an active control loop of the bidirectional charging pile virtual synchronous machine, the high-pass filter and the gain link are connected in series, and the low-pass filter and the controller are connected in series and then connected in parallel with the parallel feedforward path;
utilizing the low-pass filter and the parallel feed-forward circuit to eliminate an inherent oscillation pole in an active control loop of the bidirectional charging pile virtual synchronous machine, and further reducing a closed loop transfer function between a power command and output power to be first order;
and reducing the order of the closed loop transfer function, so that the bandwidth of an active control loop in the bidirectional charging pile virtual synchronous machine is improved.
2. The method for improving the bandwidth under the direct-current voltage stabilizing framework of the virtual synchronous machine of the bidirectional charging pile according to claim 1 is characterized in that:
the closed loop transfer function satisfies the following relationship:
wherein G is power1 For the closed loop transfer function, ΔG is the output power of the active control loop of the virtual synchronous machine of the bidirectional charging pile, ΔP ref The power command of the active control loop of the bidirectional charging pile virtual synchronous machine is represented by s which is a Lawster transformation operator, G 1 G is the transfer function of the controller 2 Is a transfer function of the power transfer model.
3. The method for improving the bandwidth under the direct current voltage stabilizing framework of the virtual synchronous machine with the bidirectional charging pile according to claim 2, wherein the transfer function of the low-pass filter satisfies the following relationship:
wherein G is 3 And s is a Lawster transformation operator, and m is a parameter.
4. The method for bandwidth improvement under a direct current voltage stabilizing architecture of a bi-directional charging pile virtual synchronous machine according to claim 3, wherein the transfer function of the high-pass filter satisfies the following relationship:
wherein G is 4 And s is a Lawster transformation operator, and m is a parameter.
5. The method for bandwidth improvement under a direct current voltage stabilizing architecture of a bi-directional charging pile virtual synchronous machine according to claim 4, wherein the transfer function of the gain element satisfies the following relationship:
wherein K is the transfer function of the gain link, m is a parameter, G 2 Is a transfer function of the power transfer model.
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