CN112448405A - VSG control method applied to self-adaptive inertia constant of electric vehicle charging pile - Google Patents

VSG control method applied to self-adaptive inertia constant of electric vehicle charging pile Download PDF

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CN112448405A
CN112448405A CN201910829106.5A CN201910829106A CN112448405A CN 112448405 A CN112448405 A CN 112448405A CN 201910829106 A CN201910829106 A CN 201910829106A CN 112448405 A CN112448405 A CN 112448405A
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charging pile
synchronous motor
virtual
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CN112448405B (en
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周昕怡
饶新亮
邢宗义
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Nanjing University of Science and Technology
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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
    • H02J3/28—Arrangements for balancing of the load in a network by storage of energy
    • H02J3/32—Arrangements for balancing of the load in a network by storage of energy using batteries with converting means
    • 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
    • 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
    • H02J3/48—Controlling the sharing of the in-phase component
    • 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
    • H02J3/50—Controlling the sharing of the out-of-phase component
    • 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
    • Y02T90/00—Enabling technologies or technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02T90/10—Technologies relating to charging of electric vehicles
    • Y02T90/12—Electric charging stations

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Charge And Discharge Circuits For Batteries Or The Like (AREA)
  • Electric Propulsion And Braking For Vehicles (AREA)

Abstract

The invention discloses a VSG control method applied to a self-adaptive inertia constant of an electric automobile charging pile, which comprises the steps of establishing a mathematical model of the electric automobile charging pile under an abc three-phase static coordinate system; establishing a virtual synchronous motor control strategy model of an AC/DC inverter in an electric automobile charging pile by simulating a rotor motion equation of a synchronous generator; determining a self-adaptive virtual inertia control strategy for a virtual synchronous motor control strategy model of an AC/DC inverter in a charging pile; and applying the self-adaptive virtual inertia control strategy to the body virtual synchronous motor body model to realize VSG control. The invention improves the running performance under system disturbance, ensures that the electric automobile load has certain demand side response regulation capacity and certain inertia and damping under the condition of ensuring the power quality of a power grid, and reduces the influence of the electric automobile load on the power grid.

Description

VSG control method applied to self-adaptive inertia constant of electric vehicle charging pile
Technical Field
The invention belongs to the power system technology, and particularly relates to a VSG control method for a self-adaptive inertia constant of an electric vehicle charging pile.
Background
At present, the control method of the electric vehicle charging pile which is the most mature research adopts Direct Power Control (DPC), and the method is feasible in effect on the electric vehicle charging pile which is tested on a small scale at present and has no great influence on a power grid. However, with the popularization and large-scale access of electric vehicles, the alternating current-direct current electric energy conversion process of the electric vehicle charging pile can bring a large amount of harmonic pollution to a power distribution network, and the stability of the power distribution network is influenced. This is mainly due to the lack of a synchronization mechanism with the distribution network for these conventional converter control strategies.
Therefore, a power grid side is in urgent need of a plurality of power grid-friendly and power grid interactive high-performance charging piles, under the condition that the power quality of a power grid is guaranteed, the electric automobile load has certain demand side response adjusting capacity and certain inertia and damping, and the influence of the electric automobile load on the power grid is reduced.
Due to the advantage that the virtual motor technology is naturally friendly to the power grid, the technology gradually becomes a research hotspot in the world at present. By using the synchronous motor technology in the traditional power grid for reference, if the charging pile of the electric automobile can be equivalently controlled to be the synchronous motor under the action of the virtual motor control strategy, the electric automobile can automatically have high-level functions of interaction with the power grid, demand side response and the like.
Disclosure of Invention
The invention aims to provide a VSG control method applied to a self-adaptive inertia constant of an electric vehicle charging pile.
The technical scheme for realizing the purpose of the invention is as follows: a VSG control method applied to a self-adaptive inertia constant of an electric vehicle charging pile comprises the following steps:
step 1, establishing a mathematical model of an electric automobile charging pile under an abc three-phase static coordinate system;
step 2, establishing a virtual synchronous motor control strategy model of an AC/DC inverter in the electric automobile charging pile by simulating a rotor motion equation of the synchronous generator;
step 3, determining a self-adaptive virtual inertia control strategy for a virtual synchronous motor control strategy model of an AC/DC inverter in a charging pile;
and 4, applying the self-adaptive virtual inertia control strategy to the body virtual synchronous motor body model to realize VSG control.
Preferably, the mathematical model of the electric vehicle charging pile established under the abc three-phase static coordinate system is specifically as follows:
Figure BDA0002190072670000011
in the formula, L and R are respectively stator inductance and resistance of the synchronous motor; e.g. of the typeabcThree-phase electromotive force of a synchronous motor; u. ofabcThe terminal voltage of the synchronous motor; i.e. iabcIs a three-phase current.
Preferably, the virtual synchronous motor control strategy model includes a virtual synchronous motor body model, an active power regulation model and a reactive power regulation model, which are respectively specifically:
the virtual synchronous motor body model is as follows:
Figure BDA0002190072670000021
where 2H is the virtual inertia constant ω is the electrical angular velocity of the synchronous machine, δ is the power angle of the generator, ω is0For synchronizing the angular speed, P, of the gride、PmElectromagnetic power and mechanical power of the synchronous motor are respectively, and D is a virtual damping coefficient;
the model of VSG active power regulation droop control comprises the following active power regulation models:
Pm＝Pref+kω(ωref-ω0)
in the formula, PrefThe reference active power is the active rated output of the direct current bus voltage; k is a radical ofωIs the sag factor; omegarefIs a reference angular frequency;
the reactive power regulation model is as follows:
Figure BDA0002190072670000022
in the formula, E, ErefRespectively an output voltage and a reference voltage; qrefIs a reference reactive power; qeOutputting reactive power for actual; kP、KIControl parameters of the PI controller; and s is an integral operator.
Preferably, the adaptive virtual inertia control strategy determined in step 3 is specifically:
Figure BDA0002190072670000023
in the formula, 2H is self-adaptive virtual inertia output by a control strategy; 2H0Is an initial virtual inertia constant; χ represents the scale of electric vehicle access; alpha is a threshold value of the access scale of the electric automobile; beta is a control constant.
Preferably, the electric vehicle is connected to the specific size | dPLoad/dt|，PLoadThe total charging power of the electric automobile in the charging pile.
Compared with the prior art, the invention has the remarkable advantages that: (1) according to the invention, through simulating a traditional generator rotor motion equation, a virtual synchronous machine technology is introduced into a charging pile control strategy, so that the whole charging pile is equivalent to a synchronous motor load, inertia and damping are provided for a power grid, and the voltage stability of an electric vehicle charging station is also improved; (2) the VSG active frequency adjusting and reactive voltage adjusting controller can realize friendly access of the electric automobile charging pile to a power distribution network, and reduces impact on equipment and a power grid when the charging automobile is accessed or quitted from the charging pile in a large scale; (3) the invention further optimizes the performance of the VSG controller by using the flexibility and the simplicity of self-adaptive control, improves the stability of the system, has clear stability mechanism and higher engineering practical value.
Drawings
Fig. 1 is a flowchart of a VSG control strategy for an adaptive virtual inertia constant of an electric vehicle charging pile according to the present invention.
Fig. 2 is a grid-connected topology structure diagram of the electric vehicle charging pile of the present invention.
FIG. 3 is a schematic diagram of the VSG control strategy for the AC/DC inverter in the charging post of the present invention.
FIG. 4 is a block diagram of the VSG control for adaptive virtual inertia based on electric vehicle charging size in accordance with the present invention.
Detailed Description
As shown in fig. 1, a VSG control method applied to an adaptive inertia constant of an electric vehicle charging pile includes the following steps:
step 1, establishing a mathematical model of an electric automobile charging pile under an abc three-phase static coordinate system;
as shown in fig. 2, the grid is connected to the charging pile through a PCC switch, where the three-phase voltage is uabc. The charging pile is composed of two parts, wherein the first part is composed of an AC/DC (alternating Current/direct Current) inverter rectifier and PWM (pulse width modulation) control thereof, which are corresponding positions of the VSG in a control strategy, and the second part is composed of a DC/DC buck converter, because the lowest input bus voltage of the direct-current grade charging equipment is usually 600V, and the voltage of the battery of the electric automobile is lower, usually 36, 48, 60, 72V and the like. An LC filter circuit is added behind the two-part converter to reduce harmonic waves and reduce current THD.
A mathematical model of an AC/DC inverter in an electric vehicle charging pile under an abc three-phase static coordinate system is that an electromagnetic equation of a synchronous motor is as follows:
Figure BDA0002190072670000031
in the formula (1), L and R are respectively a stator inductor and a resistor of the synchronous motor; u. ofabcTerminal voltages of synchronous machines, i.e. three-phase voltages at PCC switches, uabc. It is worth noting that the stator inductance L and the resistance R here correspond to the filter inductance of the DC/AC interface and the parasitic resistance of the filter (and IGBT).
And 2, establishing a virtual synchronous motor control strategy model of an AC/DC inverter in the electric vehicle charging pile by simulating a rotor motion equation of the synchronous generator, so that the whole charging pile can be equivalent to a synchronous motor load.
Further, the virtual synchronous motor control strategy model includes a virtual synchronous motor body model, an active power regulation model and a reactive power regulation model, which are respectively specifically:
referring to a traditional synchronous motor equation, a virtual synchronous motor (VSG) body model is obtained as follows:
Figure BDA0002190072670000032
in the formula (2), 2H is a virtual inertia constant, the mechanical angular velocity ω is also the electrical angular velocity of the synchronous motor, δ is the power angle of the generator, ω is0And synchronizing the angular speed of the power grid. Pe、PmThe damping coefficient is the electromagnetic power and the mechanical power of the synchronous motor (namely the active power output by a power grid at a PCC grid-connected point and the active power output by a charging pile DC/DC converter), and D is the virtual damping coefficient. Due to the existence of 2H and D, the charging pile shows mechanical inertia and the capability of damping power oscillation in the processes of power grid voltage/frequency disturbance and electric automobile load switching.
Referring to droop control of active frequency of a traditional synchronous generator, obtaining a model of VSG active regulation droop control, as follows:
Pm＝Pref+kω(ωref-ω0) (3)
in the formula, PrefThe reference active power is the active rated output of the direct current bus voltage; k is a radical ofωIs the sag factor; omegarefIs a reference angular frequency.
Substituting formula (3) into 2 can obtain:
Figure BDA0002190072670000041
the reactive voltage control of the traditional synchronous generator is referred, and a PI controller is added to obtain a VSG reactive power regulation model of
Figure BDA0002190072670000042
Furthermore, the motor electromotive force that can obtain among the electric automobile charging pile mathematical model is:
Figure BDA0002190072670000043
step 3, as shown in fig. 3, determining an adaptive virtual inertia control strategy for a virtual synchronous motor control strategy model of an AC/DC inverter in a charging pile, specifically:
Figure BDA0002190072670000044
where 2H is the adaptive virtual inertia, 2H0And x represents the scale of the electric automobile access, alpha is a threshold value, and beta is a control constant.
Because electric vehicles are various in variety and different in model, the deviation can be caused by measuring the scale of the electric vehicles by the quantity of the electric vehicles, and the most direct and practical index is the total charging power P of the electric vehicles in the charging pileLoadAnd (4) showing.
Figure BDA0002190072670000045
When the absolute value of the power change is smaller than alpha, the inertia time constant is unchanged; when it is larger than α, the inertia time constant is adaptively decreased. In order to prevent the situation that the | dP is caused by sudden power change when large-scale electric automobiles are connected into a charging pile in a short timeLoadThe value of/dt | is too large to be negative for 2H, and 2H is set to an appropriate lower limit value to prevent overflow.
And 4, applying the self-adaptive virtual inertia control strategy to the body virtual synchronous motor body model to realize VSG control, as shown in FIG. 4.
The invention replaces the traditional Direct Power Control (DPC) strategy with a control strategy based on a virtual synchronous machine (VSG) technology, looks into the control strategy from a grid-connected point, enables the whole charging pile to be equivalent to a synchronous motor load, responds to the voltage/frequency disturbance of the power grid in a self-adaptive manner, and provides necessary inertia and damping for the power grid. The adaptive virtual inertia strategy based on the electric automobile scale replaces a constant inertia constant strategy of VSG, so that the robustness and the anti-interference capability of the system can be further improved.
The alternating current interface connected with the power grid adopts a virtual synchronous motor control strategy, so that the current distortion of a grid-connected point is reduced, necessary voltage and frequency support can be provided for the power grid, and the system stability is improved. In addition, the whole charging pile can be regarded as a synchronous motor load so as to meet the requirement of response of a power grid demand side. The direct current interface connected with the electric automobile adopts an isolated DC/DC conversion circuit, can effectively realize electrical isolation with a power grid, improves the reliability of the system, and can effectively finish the quick constant-power charging of the battery of the electric automobile.

Claims (5)

1. The VSG control method for the self-adaptive inertia constant of the electric vehicle charging pile is characterized by comprising the following steps of:
step 1, establishing a mathematical model of an electric automobile charging pile under an abc three-phase static coordinate system;
step 2, establishing a virtual synchronous motor control strategy model of an AC/DC inverter in the electric automobile charging pile by simulating a rotor motion equation of the synchronous generator;
step 3, determining a self-adaptive virtual inertia control strategy for a virtual synchronous motor control strategy model of an AC/DC inverter in a charging pile;
and 4, applying the self-adaptive virtual inertia control strategy to the body virtual synchronous motor body model to realize VSG control.
2. The VSG control method applied to the adaptive inertia constant of the electric vehicle charging pile according to claim 1, wherein the mathematical model of the electric vehicle charging pile under the abc three-phase static coordinate system is specifically:
Figure FDA0002190072660000011
in the formula, L and R are respectively stator inductance and resistance of the synchronous motor; e.g. of the typeabcThree-phase electromotive force of a synchronous motor; u. ofabcThe terminal voltage of the synchronous motor; i.e. iabcIs a three-phase current.
3. The VSG control method applied to the adaptive inertia constant of the electric vehicle charging pile according to claim 1, wherein the virtual synchronous motor control strategy model comprises a virtual synchronous motor body model, an active regulation model and a reactive regulation model, which are respectively embodied as:
the virtual synchronous motor body model is as follows:
Figure FDA0002190072660000012
where 2H is the virtual inertia constant ω is the electrical angular velocity of the synchronous machine, δ is the power angle of the generator, ω is0For synchronizing the angular speed, P, of the gride、PmElectromagnetic power and mechanical power of the synchronous motor are respectively, and D is a virtual damping coefficient;
the model of VSG active power regulation droop control comprises the following active power regulation models:
Pm＝Pref+kω(ωref-ω0)
in the formula, PrefThe reference active power is the active rated output of the direct current bus voltage; k is a radical ofωIs the sag factor; omegarefIs a reference angular frequency;
the reactive power regulation model is as follows:
Figure FDA0002190072660000021
in the formula, E, ErefRespectively an output voltage and a reference voltage; qrefIs a reference reactive power; qeOutputting reactive power for actual; kP、KIControl parameters of the PI controller; and s is an integral operator.
4. The VSG control method applied to the adaptive inertia constant of the electric vehicle charging pile according to claim 1, wherein the adaptive virtual inertia control strategy determined in the step 3 is specifically as follows:
Figure FDA0002190072660000022
in the formula, 2H is self-adaptive virtual inertia output by a control strategy; 2H0Is an initial virtual inertia constant; χ represents the scale of electric vehicle access; alpha is a threshold value of the access scale of the electric automobile; beta is a control constant.
5. The VSG control method for the adaptive inertia constant of the electric vehicle charging pile according to claim 4, wherein the electric vehicle is connected to a specific scale of | dPLoad/dt|，PLoadThe total charging power of the electric automobile in the charging pile.
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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116565980A (en) * 2023-07-11 2023-08-08 麦田能源股份有限公司 Inverter system with reactive support and control method thereof

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CN104953686A (en) * 2014-03-24 2015-09-30 国家电网公司 Control method for charge-discharge virtual synchronization motor for electromobile energy storage

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CN104953686A (en) * 2014-03-24 2015-09-30 国家电网公司 Control method for charge-discharge virtual synchronization motor for electromobile energy storage

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116565980A (en) * 2023-07-11 2023-08-08 麦田能源股份有限公司 Inverter system with reactive support and control method thereof
CN116565980B (en) * 2023-07-11 2023-09-19 麦田能源股份有限公司 Inverter system with reactive support and control method thereof

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