CN117040021A - Control method and device of network-structured converter based on virtual flux linkage orientation - Google Patents
Control method and device of network-structured converter based on virtual flux linkage orientation Download PDFInfo
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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
- H02J3/38—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
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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
- H02J3/50—Controlling the sharing of the out-of-phase component
Abstract
The invention discloses a control method and a device of a network-structured converter based on virtual flux linkage orientation, wherein the method comprises the following steps: acquiring alternating-current side voltage and current of the grid-structured converter; performing virtual flux linkage measurement based on the voltage and the current, and calculating virtual flux linkage and power values of the grid-formed current transformer; performing reactive power control and active power control based on the power values, and calculating a virtual flux linkage reference signal and a synchronous electrical angle; based on the virtual flux linkage reference signal, the synchronous electrical angle and the virtual flux linkage, performing virtual flux linkage directional control, and calculating a switch control signal of the grid-built converter; controlling the grid-connected converter based on the switch control signal; the invention can realize that the grid-structured converter is connected with the power grid in a voltage source mode, thereby realizing the voltage and frequency support of the power grid and having better robustness.
Description
Technical Field
The invention relates to a control method and device of a grid-structured converter based on virtual flux linkage orientation, and belongs to the technical field of power systems.
Background
With the large-scale grid connection of new energy sources, the power system gradually shows the characteristics of high new energy source duty ratio and double high of high power electronic equipment duty ratio. The traditional synchronous motor is generally based on an electromechanical energy conversion device, so that the control system design of the synchronous motor has a mature theory; in contrast, new energy stations generally use variable current devices to convert energy, so their control systems exhibit stronger nonlinearities and uncertainties.
At present, current transformers used in new energy stations can be divided into two types, namely, heel-net transformers and grid-built transformers. The grid-structured converter realizes quick response to load fluctuation by controlling the sub-transient state and the voltage phase in the transient state, and keeps the stability of the converter. In addition, the internal voltage vector of the converter needs to be controlled to be synchronous with other power generation devices, so that the output active power and reactive power of the converter are controlled to be used for supporting the operation of the power grid. Currently, the main applications of the grid-structured current transformer include: low-strength grid support, grid frequency and voltage stabilization, power oscillation suppression, and system restart or black start.
In actual grid-connected operation, a grid-connected converter is usually regarded as a controlled voltage source, the internal voltage of which is controlled by a reactive power external loop controller or voltage regulator, and the electrical angle of which is controlled by a synchronous control loop containing active power. The operation control mode is similar to that of synchronous motor, and has the advantages of simple structure and high response speed. However, under the above control architecture, the system state variables are not directly controllable, and thus are less robust overall.
Disclosure of Invention
The invention aims to overcome the defects in the prior art, and provides a control method and device for a grid-structured converter based on virtual flux linkage orientation, which solve the technical problem of poor robustness of a control architecture of the existing grid-structured converter.
In order to achieve the above purpose, the invention is realized by adopting the following technical scheme:
in a first aspect, the present invention provides a method for controlling a network-structured converter based on virtual flux linkage orientation, including:
acquiring alternating-current side voltage and current of the grid-structured converter;
performing virtual flux linkage measurement based on the voltage and the current, and calculating virtual flux linkage and power values of the grid-formed current transformer;
performing reactive power control and active power control based on the power values, and calculating a virtual flux linkage reference signal and a synchronous electrical angle;
based on the virtual flux linkage reference signal, the synchronous electrical angle and the virtual flux linkage, performing virtual flux linkage directional control, and calculating a switch control signal of the grid-built converter;
and controlling the network-structured converter based on the switch control signal.
Optionally, the direct current side of the grid-connected converter is connected to a direct current power supply, and the alternating current side of the grid-connected converter is connected with a public bus through an LC filter;
the calculation of the virtual flux linkage of the network-structured converter comprises the following steps:
based on the voltage and the current, constructing a dynamic equation of the voltage in the grid-built converter:
wherein k=a, b, c represents a, b, c three phases, R f 、L f Is the equivalent series resistance and inductance of the LC filter, v k 、i k The alternating-current side voltage and current of the grid-formed converter; e, e k Is the voltage in the grid-built converter;
by applying the voltage v k Ac side virtual flux linkage ψ defined as the grid-formed converter k Is the derivative of:
reconstructing a dynamic equation of the voltage in the grid-structured converter:
will L f i k +ψ k Three-phase virtual flux linkage ψ defined as the grid-formed converter kv ：
ψ kv ＝L f i k +ψ k ＝L f i k +∫v k dt。
Optionally, the power value of the grid-formed converter includes active power and reactive power;
the calculation of the active power and the reactive power comprises:
virtual three-phase flux linkage psi kv Performing alpha bc/alpha beta transformation to obtain a three-phase virtual magnetic chain psi kv Is a alpha beta coordinate system component ψ αv 、ψ βv ：
ψ αv ＝L f i α +∫v α dt
ψ βv ＝L f i β +∫v β dt
In the formula, v α 、v β Is the voltage v k Alpha beta coordinate system component, i α 、i β For current i k An αβ coordinate system component of (2);
based on v α 、v β 、i α 、i β Calculating the active power P and the reactive power Q output by the grid-structured converter:
optionally, the calculating the virtual flux linkage reference signal and the synchronous electrical angle includes:
calculating the equivalent angular frequency omega' inside the network-structured converter by simulating a synchronous motor swing equation:
wherein P is * P is the active power reference value and the active power of the grid-structured converter, J is the virtual inertia, D is the damping coefficient, omega 0 Rated frequency for the system;
by integrating the frequency ω, a synchronous electrical angle θ is calculated:
θ＝∫ωdt＝∫(ω′+ω 1 )dt
wherein omega is 1 Is the output of the active current limiter;
by the principle of a virtual flux linkage reactive power controller, when the reactive power controller is used as a PQ node, the input of the reactive power controller is the reactive power reference value Q of the grid-built converter * When the reactive power controller is used as a PV nodeA point which is input as an AC side voltage reference value of the grid-formed converterThe output is magnetic linkage psi v0 Calculating virtual flux linkage reference signals
Wherein n is q For sag factor Q, Q * For the reactive power reference value and reactive power of the grid-formed converter,for an additionally applied flux linkage control signal.
Optionally, the calculating the switch control signal of the grid-configured converter includes:
for the three-phase virtual flux linkage psi kv Is a alpha beta coordinate system component ψ αv 、ψ βv Alpha beta dq conversion is carried out to obtain a three-phase virtual magnetic chain psi kv Is of the dq-axis component ψ dv 、ψ qv ；
According to the three-phase virtual flux linkage psi kv Is of the dq-axis component ψ dv 、ψ qv Defining an error variable e:
in the method, in the process of the invention,is three-phase virtual magnetic chain psi kv Is included in the dq-axis component reference value; e, e d 、e q A dq-axis component which is an error variable e;
based on the error variable e d 、e q Constructing an integral sliding mode surface S:
in χ d 、χ q For controlling constant parameters for sliding mode, S d 、S q The dq-axis component for the integral slip plane S;
the integral sliding mode surface S is derived and brought into a state equation of the grid-structured converter to obtain a derived result
Where χ=diag (χ) d ，χ q )，e dq ＝[e d ，e q ] T ，f dq ＝[f d ，f q ] T ， f dq F is the control input of the network-built converter d ，f q To control input f dq The dq-axis component of (2);
adopting improved index approach law to construct sliding mode controlThe transformation is as follows:
wherein epsilon, N, k, gamma and p are respectively approach law parameters and are constants larger than zero; s is S 0 The value of the sliding mode control when the system is in an initial state;
obtained by two simultaneous acquisitionsCalculating a control input f of the grid-connected converter dq ：
Letting the virtual flux linkage reference signalQ-axis component>Calculating a control input f dq Of (d) q-axis component f d 、f q ；
For the control input f dq Of (d) q-axis component f d 、f q Performing dq/abc conversion to obtain the internal voltage e of the network-structured converter k ；
By applying said voltage e k And obtaining a switch control signal of the grid-connected converter through a PWM link.
Optionally, the constructing of the state equation of the grid-structured converter includes:
virtual three-phase flux linkage psi kv Performing transformation derivative, and constructing a dynamic equation of the network-structured converter:
wherein T is f ＝L f /R f Representing the time constant of the LC filter;
performing abc/dq transformation on the dynamic equation of the grid-structured converter to construct the dynamic equation of the grid-structured converter in a complex plane domain:
in the psi- d 、ψ q Is virtual magnetic chain psi k Is the dq axis component of v d 、v q Is the voltage v k Is included in the (c) d q-axis component of the (c).
In a second aspect, the present invention provides a control device for a networked converter based on virtual flux linkage orientation, the device comprising:
the data acquisition module is used for acquiring the alternating-current side voltage and current of the grid-structured converter;
the virtual flux linkage measuring module is used for carrying out virtual flux linkage measurement based on the voltage and the current and calculating the virtual flux linkage and the power value of the grid-structured converter;
the power control module is used for carrying out reactive power control and active power control based on the power values and calculating a virtual flux linkage reference signal and a synchronous electrical angle;
the virtual flux linkage directional control module is used for carrying out virtual flux linkage directional control based on the virtual flux linkage reference signal, the synchronous electrical angle and the virtual flux linkage, and calculating a switch control signal of the grid-built converter;
and the converter control module is used for controlling the network-structured converter based on the switch control signal.
In a third aspect, the present invention provides an electronic device, including a processor and a storage medium;
the storage medium is used for storing instructions;
the processor is operative according to the instructions to perform steps according to the method described above.
In a fourth aspect, the present invention provides a computer readable storage medium having stored thereon a computer program which when executed by a processor performs the steps of the above method.
Compared with the prior art, the invention has the beneficial effects that:
the invention provides a control method and a device for a grid-structured converter based on virtual flux linkage orientation, which comprises the steps of firstly, determining a main circuit topology of a grid-structured converter control frame, and establishing a state equation of the grid-structured converter, wherein the virtual flux linkage is used as a state variable to participate in a dynamic process of the converter; secondly, acquiring the output voltage and current of the converter to obtain a virtual flux linkage and a power value; then, an active power synchronous control loop and a reactive power-voltage control loop are designed for smoothly outputting active power and reactive power of the converter and limiting output current of the converter, so as to obtain a virtual flux linkage directional control input signal; finally, a virtual flux linkage directional controller based on sliding mode control is designed, and after the input signal is processed, a switching input signal of the converter is generated through a PWM link; in summary, the grid-connected transformer can realize grid connection of the grid-connected transformer in a voltage source mode, so that voltage and frequency support of a power grid is realized, and the method has better robustness.
Drawings
FIG. 1 is a flowchart of a control method of a network-structured converter based on virtual flux linkage orientation according to an embodiment of the present invention;
FIG. 2 is a block diagram of a network transformer based on virtual flux linkage orientation according to an embodiment of the present invention;
fig. 3 is a schematic diagram of a control frame of a grid-structured converter according to a first embodiment of the present invention;
FIG. 4 is a schematic diagram of an active power controller according to a first embodiment of the present invention;
FIG. 5 is a schematic diagram of an active current limiter provided in accordance with a first embodiment of the present invention;
fig. 6 is a schematic diagram of a reactive power controller according to a first embodiment of the present invention;
fig. 7 is a schematic diagram of a reactive current limiter provided in accordance with a first embodiment of the present invention;
FIG. 8 is a block diagram of virtual flux linkage orientation control according to a first embodiment of the present invention;
fig. 9 is a block diagram of the dynamic equation structure of the network-structured converter according to the first embodiment of the present invention.
Detailed Description
The invention is further described below with reference to the accompanying drawings. The following examples are only for more clearly illustrating the technical aspects of the present invention, and are not intended to limit the scope of the present invention.
Embodiment one:
as shown in fig. 1-2, an embodiment of the present invention provides a control method for a network-structured converter based on virtual flux linkage orientation, including the following steps:
1. acquiring alternating-current side voltage and current of a grid-structured converter;
as shown in fig. 3, taking the control frame of the grid-structured converter provided in this embodiment as an example: the DC side of the grid-connected converter VSC is connected to a DC power supply V dc The ac side of the grid-connected converter passes through an LC filter (R f 、C f ) Connecting a public bus; the output port of the grid-built converter VSC is connected with a power grid through a circuit breaker, and the voltage of the power grid is v g The grid-connected converter VSC operates in an island mode when the switch is turned off, and operates in a grid-connected mode when the switch is turned on.
The ac side voltage and current of a grid-formed converter VSC is denoted v k 、i k K=a, b, c represents three phases a, b, c.
2. Virtual flux linkage measurement is carried out based on the voltage and the current, and virtual flux linkage and power values of the grid-formed current transformer are calculated;
(1) The virtual flux linkage of the calculation network type transformer comprises the following steps:
as shown in fig. 3, based on the voltage and current, a dynamic equation of the voltage within the grid-built converter is constructed:
wherein k=a, b, c represents a, b, c three phases, R f 、L f Is the equivalent series resistance and inductance of the LC filter, v k 、i k The alternating-current side voltage and current of the grid-formed converter; e, e k Is the voltage in the grid-built converter;
voltage v k Ac side virtual flux linkage ψ defined as a grid-formed converter k Is the derivative of:
reconstructing a dynamic equation of the voltage in the network-built converter:
will L f i k +ψ k Three-phase virtual flux linkage psi defined as grid-formed current transformer kv ：
ψ kv ＝L f i k +ψ k ＝L f i k +∫v k dt
The virtual flux linkage is the output current i of a grid-connected converter VSC k And port voltage v k A function of the correlation. As can be seen from the right half of the above, for any phase virtual flux linkage ψ kv Which is outputted by a grid-built converter VSC with a current instantaneous value i k Port voltage v k Is determined by integration of (a). Therefore, the virtual flux linkage value can be directly calculated by directly measuring the port voltage and the output current in fig. 3 and adopting the above method; in addition, due to the filter inductance value L f Relatively fixed, thus virtual flux linkage ψ kv The calculated value is approximately negligible due to the parameter variations.
(2) The calculation of the power value of the network-structured converter comprises the following steps: the power value of the grid-formed converter comprises active power and reactive power;
the calculation of the active power and the reactive power comprises the following steps:
virtual three-phase flux-linkage psi kv Performing alpha bc/alpha beta transformation to obtain a three-phase virtual magnetic chain psi kv Is a alpha beta coordinate system component ψ αv 、ψ βv ：
ψ αv ＝L f i α +∫v α dt
ψ βv ＝L f i β +∫v β dt
In the formula, v α 、v β Is the voltage v k Alpha beta coordinate system component, i α 、i β For current i k An αβ coordinate system component of (2);
based on v α 、v β 、i α 、i β Calculating the active power P and the reactive power Q output by the grid-structured converter:
3. performing reactive power control and active power control based on the power values, and calculating a virtual flux linkage reference signal and a synchronous electrical angle;
(1) As shown in fig. 4, providing an active power controller to calculate a synchronous electrical angle includes:
calculating the internal equivalent angular frequency omega' of the network-structured converter by simulating the swinging equation of the synchronous motor:
wherein P is * P is the active power reference value and the active power of the grid-formed converter, J is the virtual inertia, D is the damping coefficient, omega 0 Rated frequency for the system;
by integrating the frequency ω, a synchronous electrical angle θ is calculated:
θ＝∫ωdt＝∫(ω′+ω 1 )dt
wherein omega is 1 Is the output of the active current limiter;
as shown in fig. 5, the current that can be handled by the grid-connected converter VSC is limited. Thus, by setting upAn active current limiter for preventing the active current from exceeding a preset upper limit
Wherein I is act For active current, i.e. when the active current exceeds a predetermined limitWhen the PI controller will cause ω 0 And < 0, thereby limiting the magnitude of the synchronous phase angle theta and ultimately limiting the magnitude of the active current.
(2) As shown in fig. 6, providing a reactive power controller to calculate a virtual flux linkage reference signal includes:
by the principle of a virtual flux linkage reactive power controller, when the reactive power controller is used as a PQ node, the input of the reactive power controller is the reactive power reference value Q of the grid-structured converter * When the reactive power controller is used as the PV node, the input is the AC side voltage reference value of the grid-type converterThe output is magnetic linkage psi v0 Calculating a virtual flux linkage reference signal +.>
Wherein n is q For sag factor Q, Q * For the reactive power reference value and reactive power of the grid-formed converter,for an additionally applied flux linkage control signal.
As illustrated in fig. 7, the current that can be handled by the grid-connected converter VSC is limited. Thus, by providing a reactive current limiter to prevent reactive current exceeding a preset upper limit
Wherein I is react Is reactive current, when reactive current I react In the case of the normal range of the device,kept at 0; when reactive current I react When the limit is exceeded, the drug is added>A negative +.>For reducing the virtual flux linkage reference signal +.>Thereby limiting reactive current I react ；/>The PI controller generates +.>Is 0, and the existing reactive current value I is maintained react 。
4. Based on the virtual flux linkage reference signal, the synchronous electrical angle and the virtual flux linkage, performing virtual flux linkage directional control, and calculating a switch control signal of the grid-connected converter;
as shown in fig. 8, there is provided a virtual flux linkage directional controller based on sliding mode control, calculating a switching control signal of a grid-structured converter includes:
virtual flux linkage psi for three phases kv Is a alpha beta coordinate system component ψ αv 、ψ βv Alpha beta dq conversion is carried out to obtain a three-phase virtual magnetic chain psi kv Is of the dq-axis component ψ dv 、ψ qv ；
According to three-phase virtual flux linkage psi kv Is of the dq-axis component ψ dv 、ψ qv Defining an error variable e:
in the method, in the process of the invention,is three-phase virtual magnetic chain psi kv Is included in the dq-axis component reference value; e, e d 、e q A dq-axis component which is an error variable e;
based on error variable e d 、e q Constructing an integral sliding mode surface S:
in χ d 、χ q For controlling constant parameters for sliding mode, S d 、S q The dq-axis component for the integral slip plane S;
the integral sliding mode surface S is derived and is brought into a state equation of the grid-structured converter to obtain a derived result
Where χ=diag (χ) d ，χ q )，e dq ＝[e d ，e q ] T ，f dq ＝[f d ，f q ] T ， f dq Is the control input of the grid-structured converter, f d ，f q To control input f dq The dq-axis component of (2);
adopting improved index approach law to construct sliding mode controlThe transformation is as follows:
wherein epsilon, N, k, gamma and p are respectively approach law parameters and are constants larger than zero; s is S 0 The value of the sliding mode control when the system is in an initial state;
obtained by two simultaneous acquisitionsCalculating control input f of a grid-formed converter dq ：
Due to the virtual flux linkage vectorWhen the d-axis is coincident, the grid-formed converter VSG is in a synchronous operation state. In order to make->Is coincident with the d axis, and the q axis is referenced to the flux linkage/>Set to 0 and let this reference flux be +.>And the actual magnetic linkage psi qv Comparing and obtaining the output quantity f of the sliding mode controller q The method comprises the steps of carrying out a first treatment on the surface of the On the other hand, will->And psi is equal to dv After the same difference is made, the difference is input into a sliding mode controller to obtain f d 。
To control input f dq Of (d) q-axis component f d 、f q Performing dq/abc conversion to obtain voltage e in the network-structured converter k The method comprises the steps of carrying out a first treatment on the surface of the Voltage e k The switching control signal S of the network-structured converter is obtained through PWM link 1...6 。
5. Based on the switch control signal S 1...6 And controlling the network-structured converter.
In this embodiment, as shown in fig. 9, the construction of the state equation of the grid-structured converter includes:
virtual three-phase flux-linkage psi kv Performing transformation derivative, and constructing a dynamic equation of the network-structured converter:
wherein T is f ＝L f /R f Representing the time constant of the LC filter; psi phi type kv 、ψ k 、e k V as a state variable k As a control input;
the abc/dq conversion is carried out on the dynamic equation of the network-structured converter:
after the real part and the imaginary part are unfolded, the dynamic equation of the network-structured converter in the complex plane domain is obtained:
in the psi- d 、ψ q Is virtual magnetic chain psi k Is the dq axis component of v d 、v q Is the voltage v k Is included in the (c) d q-axis component of the (c).
Embodiment two:
the embodiment of the invention provides a control device of a network-structured converter based on virtual flux linkage orientation, which comprises the following components:
the data acquisition module is used for acquiring alternating-current side voltage and current of the grid-structured converter;
the virtual flux linkage measuring module is used for carrying out virtual flux linkage measurement based on voltage and current and calculating the virtual flux linkage and power value of the grid-formed current transformer;
the power control module is used for carrying out reactive power control and active power control based on the power values and calculating a virtual flux linkage reference signal and a synchronous electrical angle;
the virtual flux linkage directional control module is used for carrying out virtual flux linkage directional control based on the virtual flux linkage reference signal, the synchronous electrical angle and the virtual flux linkage, and calculating a switch control signal of the grid-structured converter;
and the converter control module is used for controlling the grid-built converter based on the switch control signal.
Embodiment III:
based on the first embodiment, the embodiment of the invention provides electronic equipment, which comprises a processor and a storage medium;
the storage medium is used for storing instructions;
the processor is operative according to the instructions to perform steps according to the method described above.
Embodiment four:
based on the first embodiment, the embodiment of the present invention provides a computer readable storage medium, on which a computer program is stored, which when executed by a processor, implements the steps of the above method.
It will be appreciated by those skilled in the art that embodiments of the present invention may be provided as a method, system, or computer program product. Accordingly, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
The present invention is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the invention. It will be understood that each flow and/or block of the flowchart illustrations and/or block diagrams, and combinations of flows and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
The foregoing is merely a preferred embodiment of the present invention, and it should be noted that modifications and variations could be made by those skilled in the art without departing from the technical principles of the present invention, and such modifications and variations should also be regarded as being within the scope of the invention.
Claims (9)
1. The control method of the network-structured converter based on the virtual flux linkage orientation is characterized by comprising the following steps of:
acquiring alternating-current side voltage and current of the grid-structured converter;
performing virtual flux linkage measurement based on the voltage and the current, and calculating virtual flux linkage and power values of the grid-formed current transformer;
performing reactive power control and active power control based on the power values, and calculating a virtual flux linkage reference signal and a synchronous electrical angle;
based on the virtual flux linkage reference signal, the synchronous electrical angle and the virtual flux linkage, performing virtual flux linkage directional control, and calculating a switch control signal of the grid-built converter;
and controlling the network-structured converter based on the switch control signal.
2. The control method of a grid-connected converter based on virtual flux linkage orientation according to claim 1, wherein a direct current side of the grid-connected converter is connected to a direct current power supply, and an alternating current side of the grid-connected converter is connected to a common bus through an LC filter;
the calculation of the virtual flux linkage of the network-structured converter comprises the following steps:
based on the voltage and the current, constructing a dynamic equation of the voltage in the grid-built converter:
wherein k=a, b, c represents a, b, c three phases, R f 、L f Is the equivalent series resistance and inductance of the LC filter, v k 、i k The alternating-current side voltage and current of the grid-formed converter; e, e k Is the voltage in the grid-built converter;
by applying the voltage v k Ac side virtual flux linkage ψ defined as the grid-formed converter k Is the derivative of:
reconstructing a dynamic equation of the voltage in the grid-structured converter:
will L f i k +ψ k Three-phase virtual flux linkage ψ defined as the grid-formed converter kv ：
ψ kv ＝L f i k +ψ k ＝L f i k +∫v k dt。
3. The control method of a grid-built converter based on virtual flux linkage orientation according to claim 2, wherein the power values of the grid-built converter include active power and reactive power;
the calculation of the active power and the reactive power comprises:
virtual three-phase flux linkage psi kv Performing abc/alpha beta transformation to obtain three-phase virtual magnetic chain psi kv Is a alpha beta coordinate system component ψ αv 、ψ βv ：
ψ αv ＝L f i α +∫v α dt
ψ βv ＝L f i β +∫v β dt
In the formula, v α 、v β Is of voltagev k Alpha beta coordinate system component, i α 、i β For current i k An αβ coordinate system component of (2);
based on v α 、v β 、i α 、i β Calculating the active power P and the reactive power Q output by the grid-structured converter:
4. a method of controlling a networked converter based on virtual flux linkage orientation according to claim 3, wherein the calculating virtual flux linkage reference signals and synchronous electrical angles comprises:
calculating the equivalent angular frequency omega' inside the network-structured converter by simulating a synchronous motor swing equation:
wherein P is * P is the active power reference value and the active power of the grid-structured converter, J is the virtual inertia, D is the damping coefficient, omega 0 Rated frequency for the system;
by integrating the frequency ω, a synchronous electrical angle θ is calculated:
θ＝∫ωdt＝∫(ω′+ω 1 )dt
wherein omega is 1 Is the output of the active current limiter;
by the principle of a virtual flux linkage reactive power controller, when the reactive power controller is used as a PQ node, the input of the reactive power controller is the reactive power reference value Q of the grid-built converter * When the reactive power controller is used as a PV node, the input of the reactive power controller is the AC of the grid-connected converterReference value of current side voltageThe output is magnetic linkage psi v0 Calculating a virtual flux linkage reference signal +.>
Wherein n is q For sag factor Q, Q * For the reactive power reference value and reactive power of the grid-formed converter,for an additionally applied flux linkage control signal.
5. The method of controlling a networked converter based on virtual flux linkage orientation of claim 4, wherein said calculating a switching control signal of the networked converter comprises:
for the three-phase virtual flux linkage psi kv Is a alpha beta coordinate system component ψ αv 、ψ βv Alpha beta dq conversion is carried out to obtain a three-phase virtual magnetic chain psi kv Is of the dq-axis component ψ dv 、ψ qv ；
According to the three-phase virtual flux linkage psi kv Is of the dq-axis component ψ dv 、ψ qv Defining an error variable e:
in the method, in the process of the invention,is three-phase virtual magnetic chain psi kv Is included in the dq-axis component reference value; e, e d 、e q A dq-axis component which is an error variable e;
based on the error variable e d 、e q Constructing an integral sliding mode surface S:
in χ d 、χ q For controlling constant parameters for sliding mode, S d 、S q The dq-axis component for the integral slip plane S;
the integral sliding mode surface S is derived and brought into a state equation of the grid-structured converter to obtain a derived result
Where χ=diag (χ) d ，χ q )，e dq ＝[e d ，e q ] T ，f dq ＝[f d ，f q ] T ， f dq F is the control input of the network-built converter d ，f q To control input f dq The dq-axis component of (2);
adopting improved index approach law to construct sliding mode controlThe transformation is as follows:
wherein epsilon, N, k, gamma and p are respectively approach law parameters and are constants larger than zero; s is S 0 The value of the sliding mode control when the system is in an initial state;
obtained by two simultaneous acquisitionsCalculating a control input f of the grid-connected converter dq ：
Letting the virtual flux linkage reference signalQ-axis component>Calculating a control input f dq Of (d) q-axis component f d 、f q ；
For the control input f dq Of (d) q-axis component f d 、f q Performing dq/abc conversion to obtain the internal voltage e of the network-structured converter k ；
By applying said voltage e k And obtaining a switch control signal of the grid-connected converter through a PWM link.
6. The method for controlling a networked converter based on virtual flux linkage orientation according to claim 5, wherein the constructing of the state equation of the networked converter includes:
virtual three-phase flux linkage psi kv Proceeding withTransforming and deriving, and constructing a dynamic equation of the network-structured converter:
wherein T is f ＝L f /R f Representing the time constant of the LC filter;
performing abc/dq transformation on the dynamic equation of the grid-structured converter to construct the dynamic equation of the grid-structured converter in a complex plane domain:
in the psi- d 、ψ q Is virtual magnetic chain psi k Is the dq axis component of v d 、v q Is the voltage v k Is included in the (c) d q-axis component of the (c).
7. A control device for a networked converter based on virtual flux linkage orientation, the device comprising:
the data acquisition module is used for acquiring the alternating-current side voltage and current of the grid-structured converter;
the virtual flux linkage measuring module is used for carrying out virtual flux linkage measurement based on the voltage and the current and calculating the virtual flux linkage and the power value of the grid-structured converter;
the power control module is used for carrying out reactive power control and active power control based on the power values and calculating a virtual flux linkage reference signal and a synchronous electrical angle;
the virtual flux linkage directional control module is used for carrying out virtual flux linkage directional control based on the virtual flux linkage reference signal, the synchronous electrical angle and the virtual flux linkage, and calculating a switch control signal of the grid-built converter;
and the converter control module is used for controlling the network-structured converter based on the switch control signal.
8. An electronic device, comprising a processor and a storage medium;
the storage medium is used for storing instructions;
the processor being operative according to the instructions to perform the steps of the method according to any one of claims 1-6.
9. A computer readable storage medium, on which a computer program is stored, characterized in that the program, when being executed by a processor, implements the steps of the method according to any one of claims 1-7.
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| CN117595409B (en) * | 2024-01-19 | 2024-04-02 | 国网湖北省电力有限公司 | Active power control method and related device for virtual synchronous machine of network-structured converter |
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