CN112968452A - Control method and device of converter - Google Patents
Control method and device of converter Download PDFInfo
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Abstract
The application discloses a control method and a control device of a converter, wherein the method comprises the following steps: determining the actual output power of the converter according to the three-phase output voltage and the three-phase current of the converter; determining a coordinate transformation angle according to the active power and the active-frequency control model, and determining a positive sequence component of a modulation wave according to the reactive power and the reactive-voltage control model; determining a voltage negative sequence control instruction and voltage negative sequence control feedback according to the operation mode of the converter, and determining a negative sequence d-axis component of a modulated wave and a negative sequence q-axis component of the modulated wave, thereby determining the modulated wave under a dq-axis coordinate system; and carrying out coordinate transformation on the modulation wave in the dq axis coordinate system to obtain a modulation signal in the abc coordinate system, and driving the converter to work according to the modulation signal. The method has the advantages of simple structure and small calculation amount, and can reduce the unbalance degree of the off-grid output voltage while ensuring the basic characteristics of the voltage type VSG; the unbalance degree of the grid-connected current can be reduced, and voltage and frequency support is provided for the system.
Description
Technical Field
The application belongs to the technical field of energy storage systems, and particularly relates to a control method and device of a converter.
Background
In order to improve the operational reliability of the energy storage system, scholars at home and abroad propose a Virtual Synchronous Generator (VSG) technology, and the technology enables an energy storage converter to be comparable to a traditional generator in external characteristics and an operation mechanism by simulating characteristics such as a body model, active frequency modulation and reactive voltage regulation of a synchronous generator. However, with the variability of energy storage devices and the wide range of applications, there are a large number of unbalanced loads in the system, and various unbalanced faults may occur, which may cause an imbalance in the system voltage or the network current.
In the existing VSG control method, aiming at the problem of unbalanced three-phase voltage output when an off-net belt is in unbalanced load, most of the existing VSG control methods adopt an unbalanced voltage compensation control strategy based on VSG, and the method is simple and reliable, can realize the capability of compensating the unbalanced voltage, but is not suitable for the unbalanced working condition of the three-phase power grid voltage; for the problem of unbalanced three-phase network current when the grid-connected power grid voltage is unbalanced, a power-current control method is generally adopted, or negative sequence component control based on a voltage current double loop is adopted, the former improves the problems of current quality and the like by calculating a reference value of current, but the method is not suitable for an off-grid load unbalanced working condition based on a current type VSG, and the latter control logic is relatively complex.
It should be noted that the statements herein merely provide background information related to the present application and may not necessarily constitute prior art.
Disclosure of Invention
The invention aims to provide a control method and a control device of a converter, which can reduce the unbalance degree of an off-grid output voltage and improve the capacity of a VSG with an off-grid unbalanced load on the premise of ensuring the basic control attribute of the VSG; the unbalance degree of grid-connected current can be reduced, and the fault ride-through capability during the unbalanced voltage of the power grid is achieved.
According to an aspect of the present application, there is provided a control method of a converter, including:
determining the actual output power of the converter according to the three-phase output voltage and the three-phase current of the converter, wherein the actual output power comprises active power and reactive power;
determining a coordinate transformation angle according to the active power and the active-frequency control model, and determining a positive sequence d-axis component of the modulated wave according to the reactive power and the reactive-voltage control model, so that the positive sequence q-axis component of the modulated wave is fixed to be 0; the active-frequency control model and the reactive-voltage control model are obtained based on a Virtual Synchronous Generator (VSG) model;
determining a voltage negative sequence control instruction and voltage negative sequence control feedback according to the operation mode of the converter, and determining a negative sequence d-axis component of a modulating wave and a negative sequence q-axis component of the modulating wave according to the voltage negative sequence control instruction and the voltage negative sequence control feedback, so that the modulating wave under a dq-axis coordinate system is determined according to the positive sequence d-axis component of the modulating wave, the positive sequence q-axis component of the modulating wave, the negative sequence d-axis component of the modulating wave and the negative sequence q-axis component of the modulating wave;
and based on the coordinate transformation angle, carrying out coordinate transformation on the modulation wave in the dq axis coordinate system to obtain a modulation signal in the abc coordinate system, and driving the converter to work according to the modulation signal.
Preferably, in the above method, the determining a negative voltage sequence control command and a negative voltage sequence control feedback according to the operation mode of the converter, and the determining a negative sequence d-axis component of the modulated wave and a negative sequence q-axis component of the modulated wave according to the negative voltage sequence control command and the negative voltage sequence control feedback includes:
if the operation mode of the converter is off-grid operation, making a voltage negative sequence control command be 0, and performing positive-negative sequence separation on three-phase output voltage of the converter to obtain a negative sequence d-axis component of the output voltage and a negative sequence q-axis component of the output voltage as voltage negative sequence control feedback;
and obtaining a negative sequence d-axis component of the modulating wave and a negative sequence q-axis component of the modulating wave when the converter is in off-grid operation through PI control according to the voltage negative sequence control instruction and the voltage negative sequence control feedback.
Optionally, in the above method, determining a negative voltage sequence control command and a negative voltage sequence control feedback according to the operation mode of the converter, and determining a negative sequence d-axis component of the modulated wave and a negative sequence q-axis component of the modulated wave according to the negative voltage sequence control command and the negative voltage sequence control feedback, includes:
if the operation mode of the converter is grid-connected operation, respectively carrying out positive and negative sequence separation on three-phase output voltage and three-phase power grid voltage of the converter to obtain a negative sequence d-axis component of the power grid voltage and a negative sequence q-axis component of the power grid voltage, and using the negative sequence d-axis component of the output voltage and the negative sequence q-axis component of the output voltage as a voltage negative sequence control instruction to obtain a negative sequence d-axis component of the output voltage and a negative sequence q-axis component of the output voltage as voltage negative sequence control feedback;
and obtaining a negative sequence d-axis component of the modulation wave and a negative sequence q-axis component of the modulation wave when the converter is connected to the grid and operated by PI control according to the voltage negative sequence control instruction and the voltage negative sequence control feedback.
Optionally, in the above method, obtaining a negative sequence d-axis component of a modulated wave and a negative sequence q-axis component of the modulated wave when the converter is in off-grid operation by PI control according to the negative voltage sequence control instruction and the negative voltage sequence control feedback, includes:
calculating the negative sequence d-axis component of the modulating wave and the negative sequence q-axis component of the modulating wave when the converter runs off the grid by the following formula:
wherein the content of the first and second substances,
is the negative sequence d-axis component of the modulated wave, 0 is the voltage negative sequence control command,
being the negative sequence d-axis component of the output voltage,
for the negative-sequence q-axis component of the modulated wave,
is negative of the output voltageQ-axis component, G(s) is a proportional integral regulator transfer function;
wherein the content of the first and second substances,
kP、kIfor conventional proportional integral regulator coefficients, s is a time-dependent function determined according to automatic control theory.
Optionally, in the method, the obtaining, according to the negative voltage sequence control instruction and the negative voltage sequence control feedback, a negative sequence d-axis component of the modulated wave and a q-axis component of the modulated wave during the grid-connected operation of the converter through PI control includes:
calculating a negative sequence d-axis component of a modulation wave and a negative sequence q-axis component of the modulation wave when the converter is in grid-connected operation by the following formula:
wherein the content of the first and second substances,
for the negative sequence d-axis component of the modulated wave,
being the negative sequence d-axis component of the grid voltage,
being the negative sequence d-axis component of the output voltage,
for the negative-sequence q-axis component of the modulated wave,
being the negative sequence q-axis component of the grid voltage,
is the negative sequence q-axis component of the output voltage, G(s) is the proportional-integral regulator transfer function;
wherein the content of the first and second substances,
kP、kIfor conventional proportional integral regulator coefficients, s is a time-dependent function determined according to automatic control theory.
Optionally, in the method, determining the actual output power of the converter according to the three-phase output voltage and the three-phase current of the converter includes:
determining the actual output power of the converter according to the following calculation formula:
wherein, PeActive power; q is reactive power; u. ofa、ub、ucThree-phase output voltages of the converter are respectively; i.e. ia、ib、icThree-phase currents of the converter are respectively; gc(s) is the transfer function of a second order low pass filter, GcThe formula for calculation of(s) is:
wherein, ω isnIs the natural angular frequency of the second order low pass filter, ξ is the damping coefficient of the second order low pass filter, and s is a time-dependent function determined according to the automatic control theory.
Optionally, in the foregoing method, determining a coordinate transformation angle according to the active power and the active-frequency control model includes:
determining the angular frequency of the rotor according to the active power and the active-frequency control model, and integrating the angular frequency of the rotor to obtain a coordinate transformation angle;
wherein, the active-frequency control model includes a rotor equation of motion and a prime mover equation of motion, wherein the rotor equation of motion is:
wherein, ω isNRated rotor angular frequency, omega rotor angular frequency; J. d is respectively a rotational inertia and a damping coefficient; pmIs mechanical power, PeActive power; delta is a power angle;
the prime mover regulation equation is:
Pm＝Pref+kf(ωN-ω)，
wherein, PrefAs an active power command, kfIs the active frequency modulation coefficient.
Optionally, in the method, determining the positive sequence d-axis component of the modulated wave according to the reactive power and the reactive-voltage control model includes:
the positive sequence d-axis component of the modulated wave is made to be electromotive force EmElectromotive force EmDetermining according to a reactive power and a reactive-voltage control model, wherein the reactive-voltage control model is as follows:
wherein E ismIs electromotive force; qrefIs a reactive power command; u shapeNIs a nominal phase voltage amplitude; k is a reactive inertia coefficient; k is a radical ofvIs a reactive voltage regulation coefficient; q is reactive power; u shapemIs the voltage amplitude of the converter.
According to another aspect of the present application, there is provided a control apparatus of a converter, including:
the power determining unit is used for determining the actual output power of the converter according to the three-phase output voltage and the three-phase current of the converter, wherein the actual output power comprises active power and reactive power;
the positive sequence component determining unit is used for determining a coordinate transformation angle according to the active power and the active-frequency control model, determining a positive sequence d-axis component of the modulating wave according to the reactive power and the reactive-voltage control model, and fixing a positive sequence q-axis component of the modulating wave to be 0; the active-frequency control model and the reactive-voltage control model are obtained based on a Virtual Synchronous Generator (VSG) model;
the negative sequence component determining unit is used for determining a voltage negative sequence control instruction and voltage negative sequence control feedback according to the operation mode of the converter, and determining a negative sequence d-axis component of the modulating wave and a negative sequence q-axis component of the modulating wave according to the voltage negative sequence control instruction and the voltage negative sequence control feedback, so that the modulating wave under a dq-axis coordinate system is determined according to the positive sequence d-axis component of the modulating wave, the positive sequence q-axis component of the modulating wave, the negative sequence d-axis component of the modulating wave and the negative sequence q-axis component of the modulating wave;
and the coordinate transformation unit is used for carrying out coordinate transformation on the modulation wave in the dq axis coordinate system based on the coordinate transformation angle to obtain a modulation signal in the abc coordinate system, so as to drive the converter to work according to the modulation signal.
Optionally, in the above apparatus, the negative sequence component determining unit is configured to, if the operation mode of the converter is off-grid operation, set the voltage negative sequence control instruction to 0, perform positive-negative sequence separation on three-phase output voltages of the converter, to obtain a negative sequence d-axis component of the output voltage and a negative sequence q-axis component of the output voltage, and use the negative sequence d-axis component and the negative sequence q-axis component as voltage negative sequence control feedback; and the PI control unit is used for obtaining a negative sequence d-axis component of the modulating wave and a negative sequence q-axis component of the modulating wave when the converter is in off-grid operation according to the voltage negative sequence control instruction and the voltage negative sequence control feedback.
Optionally, in the above apparatus, the negative sequence component determining unit is configured to, if the operation mode of the converter is grid-connected operation, respectively perform positive-negative sequence separation on the three-phase output voltage of the converter and the three-phase grid voltage to obtain a negative sequence d-axis component of the grid voltage and a negative sequence q-axis component of the grid voltage, and obtain the negative sequence d-axis component of the output voltage and the negative sequence q-axis component of the output voltage as a voltage negative sequence control instruction, and use the negative sequence d-axis component of the output voltage and the negative sequence q-axis component as voltage negative sequence control feedback; and the negative sequence d and q axis components of the modulation wave are obtained by PI control when the converter is connected with the grid and operates according to the voltage negative sequence control instruction and the voltage negative sequence control feedback.
Optionally, in the above apparatus, the negative sequence component determining unit is configured to calculate a negative sequence d-axis component of the modulated wave and a negative sequence q-axis component of the modulated wave when the converter is in off-grid operation by using the following formulas:
wherein the content of the first and second substances,
is the negative sequence d-axis component of the modulated wave, 0 is the voltage negative sequence control command,
being the negative sequence d-axis component of the output voltage,
for the negative-sequence q-axis component of the modulated wave,
is the negative sequence q-axis component of the output voltage, G(s) is the proportional-integral regulator transfer function;
wherein the content of the first and second substances,
kP、kIfor conventional proportional integral regulator coefficients, s is a time-dependent function determined according to automatic control theory.
Optionally, in the above apparatus, the negative sequence component determining unit is configured to calculate a negative sequence d-axis component of the modulated wave and a negative sequence q-axis component of the modulated wave when the converter is in grid-connected operation by using the following formulas:
wherein the content of the first and second substances,
for the negative sequence d-axis component of the modulated wave,
being the negative sequence d-axis component of the grid voltage,
being the negative sequence d-axis component of the output voltage,
for the negative-sequence q-axis component of the modulated wave,
being the negative sequence q-axis component of the grid voltage,
is the negative sequence q-axis component of the output voltage, G(s) is the proportional-integral regulator transfer function;
wherein the content of the first and second substances,
kP、kIfor conventional proportional integral regulator coefficients, s is a time-dependent function determined according to automatic control theory.
Optionally, in the above apparatus, the power determining unit is configured to determine the actual output power of the converter according to the following calculation formula:
wherein, PeActive power; q is reactive power; u. ofa、ub、ucThree-phase output voltages of the converter are respectively; i.e. ia、ib、icThree-phase currents of the converter are respectively; gc(s) is the transfer function of a second order low pass filter, GcThe formula for calculation of(s) is:
wherein, ω isnIs the natural angular frequency of the second order low pass filter, ξ is the damping coefficient of the second order low pass filter, and s is a time-dependent function determined according to the automatic control theory.
Optionally, in the above apparatus, the positive sequence component determining unit is configured to determine a rotor angular frequency according to the active power and an active-frequency control model, and integrate the rotor angular frequency to obtain a coordinate transformation angle;
wherein, the active-frequency control model includes a rotor equation of motion and a prime mover equation of motion, wherein the rotor equation of motion is:
wherein, ω isNRated rotor angular frequency, omega rotor angular frequency; J. d is respectively a rotational inertia and a damping coefficient; pmIs mechanical power, PeActive power; delta is a power angle;
the prime mover regulation equation is:
Pm＝Pref+kf(ωN-ω)，
wherein, PrefAs an active power command, kfIs the active frequency modulation coefficient.
Optionally, in the above apparatus, the positive sequence component determining unit is configured to make the positive sequence d-axis component of the modulated wave be the electromotive force EmElectromotive force EmDetermining according to a reactive power and a reactive-voltage control model, wherein the reactive-voltage control model is as follows:
wherein E ismIs electromotive force; qrefIs a reactive power command; u shapeNIs a nominal phase voltage amplitude; k is a reactive inertia coefficient; k is a radical ofvIs a reactive voltage regulation coefficient; q is reactive power; u shapemAs voltage amplitude of current transformerThe value is obtained.
According to a third aspect of the present application, there is provided a converter comprising a control device of any one of the converters described above.
The beneficial effect of this application lies in: aiming at the working conditions of VSG off-grid load imbalance and grid-connected power grid voltage imbalance, the voltage type VSG control method for the converter under the imbalance working conditions is provided, the control method is simple in calculation structure and small in calculation amount, the basic characteristics of the voltage type VSG are guaranteed, the off-grid output voltage imbalance degree can be reduced, and the capability of the VSG with the off-grid imbalance load is improved; the unbalance degree of grid-connected current can be reduced, the fault ride-through capability during the unbalance of the grid voltage is realized, and the voltage and frequency support is provided for the system; compared with the VSG unbalance control method in the prior art, the VSG unbalance control method is suitable for various unbalance working conditions, simple and reliable in control structure, clear in system working operation mode and high in response speed; the problems of reducing the quality of electric energy, such as harmonic interference, current distortion, large-amplitude power oscillation and the like, are avoided, the service life of an electronic device is prolonged, and the reliability of the integral work of the converter is improved.
As is apparent from the above description, the technical solutions of the present application are only the outline of the technical solutions of the present application, and the embodiments of the present application will be described below in order to make the technical means of the present application more clearly understood, and to make the above and other objects, features, and advantages of the present application more obvious.
Drawings
Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the application. Also, like reference numerals are used to refer to like parts throughout the drawings. In the drawings:
fig. 1 shows a flow diagram of a control method of a converter according to an embodiment of the present application;
fig. 2 shows a main topology of a converter connected to a grid according to an embodiment of the present application;
fig. 3 shows a flow diagram of a control method of a converter according to another embodiment of the present application;
FIG. 4 shows a block diagram of a control method of a converter according to an embodiment of the present application;
fig. 5 shows a schematic configuration of a control device of a converter according to an embodiment of the present application;
FIG. 6 shows a schematic structural diagram of an electronic device according to an embodiment of the present application;
FIG. 7 shows a schematic structural diagram of a computer-readable storage medium according to an embodiment of the present application.
Detailed Description
Exemplary embodiments of the present application will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the present application are shown in the drawings, it should be understood that the present application may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.
The method is characterized in that a voltage type VSG control method suitable for unbalanced working conditions is provided based on the traditional voltage type VSG aiming at unbalanced off-grid loads and unbalanced grid voltage, and a set of control method is provided aiming at different working states of a converter, so that the capacity of the system with unbalanced loads during off-grid operation can be improved, the operation performance of the system during unbalanced grid voltage can be improved, and voltage and frequency support is provided for the system.
Fig. 1 shows a schematic flow chart of a control method of a converter according to an embodiment of the present application, and as can be seen from fig. 1, the method includes:
step S110, determining the actual output power of the converter according to the three-phase output voltage and the three-phase current of the converter, wherein the actual output power comprises active power and reactive power. The actual output power includes the active power PeAnd reactive power Q.
In some embodiments of the present application, the calculation formula of the actual output power of the converter is:
wherein, PeActive power; q is reactive power; u. ofa、ub、ucThree-phase output voltages of the converter are respectively; i.e. ia、ib、icThree-phase currents of the converter are respectively; gc(s) is the transfer function of a second order low pass filter, GcThe formula for calculation of(s) is:
wherein, ω isnIs the natural angular frequency of the second order low pass filter, ξ is the damping coefficient of the second order low pass filter, and s is a time-dependent function determined according to the automatic control theory.
Step S120, determining a coordinate transformation angle according to the active power and the active-frequency control model, and determining a positive sequence d-axis component of the modulating wave according to the reactive power and the reactive-voltage control model, so that the positive sequence q-axis component of the modulating wave is fixed to be 0; the active-frequency control model and the reactive-voltage control model are obtained based on virtual synchronous generator VSG modeling.
The method comprises the steps that an active-frequency control model and a reactive-voltage control model which take actual output power of a converter as input quantity are established based on a Virtual Synchronous Generator (VSG), wherein a coordinate transformation angle can be determined according to output quantity of the active-frequency control model, the angle is used as a transformation angle for subsequent coordinate transformation, and output quantity of the reactive-voltage control model is a modulation wave positive sequence d-axis component. The active-frequency control model comprises a prime motor regulation equation and a rotor motion equation; the reactive-voltage control model is established through a reactive voltage droop relation.
In some embodiments of the present application, the active-frequency control model comprises a rotor equation of motion and a prime mover governing equation, wherein the rotor equation of motion is:
wherein, ω isNRated rotor angular frequency, omega rotor angular frequency; J. d is respectively a rotational inertia and a damping coefficient; pmIs mechanical power, PeActive power; delta is a power angle;
the prime mover regulation equation is:
Pm＝Pref+kf(ωN-ω)，
wherein, PrefAs an active power command, kfIs the active frequency modulation coefficient.
According to the obtained actual output active power PeAnd converter active power instruction PrefRated angular frequency omegaNThe output angular frequency omega can be obtained through an active-frequency control model, and the angular frequency omega is integrated to obtain a VSG vector angle theta which is used as a coordinate transformation angle.
In some embodiments of the present application, the reactive-voltage control model is:
wherein E ismIs electromotive force; qrefIs a reactive power command; u shapeNIs a nominal phase voltage amplitude; k is a reactive inertia coefficient; k is a radical ofvIs a reactive voltage regulation coefficient; q is reactive power; u shapemIs the voltage amplitude of the converter.
Electromotive force E obtained by the reactive-voltage control modelmCan be used as the positive sequence d-axis component of the modulated wave
Modulated wave positive sequence q-axis component
Fixed to 0, modulated wave positive sequence d-axis component
And the positive sequence q-axis component of the modulated wave
Together constitute the positive sequence component of the modulated wave.
Step S130, determining a voltage negative sequence control command and a voltage negative sequence control feedback according to the operation mode of the converter, and determining a negative sequence d-axis component of the modulated wave and a negative sequence q-axis component of the modulated wave according to the voltage negative sequence control command and the voltage negative sequence control feedback, so that the modulated wave under a dq-axis coordinate system is determined according to the positive sequence d-axis component of the modulated wave, the positive sequence q-axis component of the modulated wave, the negative sequence d-axis component of the modulated wave and the negative sequence q-axis component of the modulated wave.
According to the method, different negative sequence control models are provided according to the operation mode of the converter, when a PCC point switch is in a disconnected state, the converter works in an off-grid operation mode, at the moment, the voltage of a power grid of the converter is 0V, a voltage negative sequence control switch S is turned to a 0 gear, a voltage negative sequence control command is 0 and is fed back to an output voltage negative sequence component, and the balance of output voltage when three-phase unbalanced load exists can be guaranteed; when the PCC point switch is closed and the detected grid voltage is normal, the converter works in a grid-connected operation state, the voltage negative sequence control switch S is switched to 1 gear, the voltage negative sequence control command is a three-phase grid voltage negative sequence component, the three-phase output voltage negative sequence component is fed back, and the balance of three-phase grid-connected current can be ensured when the grid is unbalanced.
In the above method, determining a negative voltage sequence control command and feedback according to the operation mode of the converter, and determining a negative sequence d-axis component and a negative sequence q-axis component of the modulated wave according to the negative voltage sequence control comprises: if the operation mode of the converter is off-grid operation, the other voltage negative sequence control command is 0, and the three-phase output voltage u of the converter is subjected toa、ub、ucCarrying out positive and negative sequence separation to obtain negative sequence d-axis component of output voltage
Negative sequence q-axis component of output voltage
As negative voltage sequence control feedback; and obtaining a negative sequence d-axis component of the modulation wave and a negative sequence q-axis component of the modulation wave when the converter is in off-grid operation through PI control according to the voltage negative sequence control instruction and the voltage negative sequence control feedback.
If the operation mode of the converter is grid-connected operation, the three-phase output voltage u to the convertera、ub、ucAnd three-phase network voltage uga、ugb、ugcRespectively carrying out positive and negative sequence separation to obtain the negative sequence d-axis component of the grid voltage
Negative sequence q-axis component of grid voltage
Obtaining the negative sequence d-axis component of the output voltage as the voltage negative sequence control command
Negative sequence q-axis component of output voltage
As negative voltage sequence control feedback; and obtaining a d-axis component of the modulating wave and a negative sequence q-axis component of the modulating wave when the converter is in off-grid operation through PI control according to the voltage negative sequence control instruction and the voltage negative sequence control feedback. The positive and negative sequence separation can be achieved by any one of the prior art.
In particular, the negative sequence d-axis component of the modulated wave during off-grid operation of the converter
Negative sequence q-axis component of modulated wave
The calculation formula of (2) is as follows:
wherein G isc(s) is a proportional integral regulator transfer function,
kP、kIfor conventional proportional integral regulator coefficients, s is a time-dependent function determined according to automatic control theory.
When the converter works in an off-grid operation mode and is provided with an unbalanced load, the voltage at the bridge port of the traditional voltage type VSG is balanced in three phases, the output voltage and the current are unbalanced, and the control goals of balancing the output voltage and reducing the fluctuation of active power or reactive power are to be achieved, at the moment, the negative sequence component of the output voltage is required to be 0, and therefore the reference value of the negative sequence voltage is set to be 0.
Negative sequence d-axis component e of modulation wave during grid-connected operation of converter- dnNegative sequence q-axis component e of modulated wave- qnThe calculation formula of (2) is as follows:
wherein G isc(s) is a proportional integral regulator transfer function,
kP、kIfor conventional proportional integral regulator coefficients, s is a time-dependent function determined according to automatic control theory.
When the converter works in a grid-connected operation mode and the voltage of a three-phase power grid is unbalanced, the control goals of balancing output current and reducing active power or reactive power fluctuation are realized, at the moment, the negative sequence component of the output current is required to be 0, and when the negative sequence component of the current is 0, the negative sequence component of the bridge port voltage is equal to the negative sequence component of the power grid voltage, so that the negative sequence power is setReference value of pressure is
And step S140, performing coordinate transformation on the modulation wave in the dq axis coordinate system based on the coordinate transformation angle to obtain a modulation signal in the abc coordinate system, and driving the converter to work according to the modulation signal.
The method shown in fig. 1 shows that a voltage type VSG control method for a converter suitable for unbalanced working conditions is provided for VSG off-grid load unbalanced and grid-connected grid voltage unbalanced working conditions, the control method is simple in calculation structure and small in calculation amount, the basic characteristics of the voltage type VSG are guaranteed, the off-grid output voltage unbalanced degree can be reduced, and the capability of the VSG with the off-grid unbalanced load is improved; the unbalance degree of grid-connected current can be reduced, the fault ride-through capability during the unbalance of the grid voltage is realized, and the voltage and frequency support is provided for the system; compared with the VSG unbalance control method in the prior art, the VSG unbalance control method is suitable for various unbalance working conditions, simple and reliable in control structure, clear in system working operation mode and high in response speed; the problems of reducing the quality of electric energy, such as harmonic interference, current distortion, large-amplitude power oscillation and the like, are avoided, the service life of an electronic device is prolonged, and the reliability of the integral work of the converter is improved.
In some embodiments of the present application, the method further comprises: detecting the state of a PCC point switch, and determining the operation mode of the converter according to the state of the PCC point switch; determining that the operation mode of the converter is off-grid operation under the condition that the PCC point switch is in an off state; and under the condition that the PCC point switch is in a closed state, determining that the operation mode of the converter is grid-connected operation.
Fig. 2 shows a main topology of a converter connected to a grid according to an embodiment of the application, in fig. 2 the right circle of the PCC point switch is a three-phase grid uga、ugb、ugc(ii) a A current transformer is arranged in a left side box of the PCC point switch, and when the PCC point switch is closed, the current transformer is in a grid-connected working state; when the PCC point switch is disconnected, the converter is in an off-grid working state.
In fig. 2, the functions of the electronic devices such as the filter inductor (L), the inductor internal resistance (R), the filter capacitor (C) and the like of the converter are the same as those in the prior art, and the three-phase output voltages of the converter are ua、ub、ucThree phase currents are respectively ia、ib、ic(ii) a The method of the present application can be used in, but is not limited to, the conventional two-level converter of fig. 2.
Fig. 3 shows a detailed flow diagram of a control method of a converter according to an embodiment of the present application.
And calculating the actual output power of the converter, including active power and reactive power, according to the three-phase output voltage and the three-phase current of the converter. And determining output angular frequency according to each active power-frequency control model of the active power, and integrating the output angular frequency to obtain a vector angle serving as a coordinate transformation angle. Determining an electromotive force E from the reactive power and reactive-voltage control modelmElectromotive force EmAs the modulated wave positive sequence d-axis component, the positive sequence q-axis component is fixed to 0. And determining a voltage negative sequence control command according to the operation mode of the converter, and determining d and q axis components of a modulation wave negative sequence according to the voltage negative sequence control. And based on the coordinate transformation angle, transforming the positive sequence d, q-axis components, the negative sequence d and q-axis components of the modulation wave in the dq coordinate system into the abc coordinate system through park transformation to obtain a three-phase modulation signal.
The specific calculation process of the above embodiment may refer to fig. 4, where fig. 4 shows a block diagram of a control method of a converter according to an embodiment of the present application, in fig. 4, a first line represents an active-frequency control model, and a vector angle θ may be obtained through calculation; the second line represents a reactive-voltage control model, and electromotive force E can be obtained through calculationmAs the positive sequence d-axis component of the modulated wave
And let the positive sequence q-axis component
Is 0.
Referring to FIG. 4, examineAnd (4) measuring the on-off state of the PCC, and when the PCC is switched off, turning the negative sequence voltage control switch S to a 0 gear aiming at the off-grid unbalance, wherein the converter works in an off-grid operation mode at the moment. When the negative sequence voltage control switch S is turned to 0 gear, respectively using 0 and 0
And
making difference, and processing by conventional proportional integral regulator coefficient regulator to obtain modulated wave negative sequence d and q axis components
When the PCC point switch is closed, the negative sequence voltage control switch S is turned to 1 gear aiming at the unbalanced grid-connected power grid voltage, and at the moment, the converter works in a grid-connected operation mode and is respectively used
And
and
and
making difference, and processing by conventional proportional integral regulator coefficient regulator to obtain modulated wave negative sequence d and q axis components
And finally, performing coordinate transformation on the modulation waves by taking the vector angle theta as a coordinate transformation angle to obtain modulation signals, wherein the modulation signals are six driving waves and respectively drive driving circuits S1-S6 in the figure 2 to control the operation of the converter.
Fig. 5 is a structural device diagram of a control device of a converter according to an embodiment of the present application, and as can be seen from fig. 5, the device 500 includes:
and a power determining unit 510, configured to determine actual output power of the converter according to the three-phase output voltage and the three-phase current of the converter, where the actual output power includes active power and reactive power.
A positive sequence component determining unit 520, configured to determine a coordinate transformation angle according to the active power and the active-frequency control model, and determine a positive sequence d-axis component of the modulated wave according to the reactive power and the reactive-voltage control model, so that a positive sequence q-axis component of the modulated wave is fixed to 0; the active-frequency control model and the reactive-voltage control model are obtained based on virtual synchronous generator VSG modeling.
And a negative sequence component determination unit 530, configured to determine a voltage negative sequence control command and a voltage negative sequence control feedback according to the operation mode of the converter, and determine a negative sequence d-axis component of the modulated wave and a negative sequence q-axis component of the modulated wave according to the voltage negative sequence control command and the voltage negative sequence control feedback, so that the modulated wave in the dq-axis coordinate system is determined according to the positive sequence d-axis component of the modulated wave, the positive sequence q-axis component of the modulated wave, the negative sequence d-axis component of the modulated wave, and the negative sequence q-axis component of the modulated wave.
And a coordinate transformation unit 540, configured to perform coordinate transformation on the modulation wave in the dq axis coordinate system based on the coordinate transformation angle to obtain a modulation signal in the abc coordinate system, so as to drive the converter to operate according to the modulation signal.
In some embodiments of the present application, in the above apparatus, the negative sequence component determining unit 520 is configured to make the voltage negative sequence control command to be 0 if the operation mode of the converter is off-grid operation, and perform positive-negative sequence separation on the three-phase output voltage of the converter to obtain a negative sequence d-axis component of the output voltage and a negative sequence q-axis component of the output voltage as voltage negative sequence control feedback; and the PI control unit is used for obtaining a negative sequence d-axis component of the modulating wave and a negative sequence q-axis component of the modulating wave when the converter is in off-grid operation according to the voltage negative sequence control instruction and the voltage negative sequence control feedback.
In some embodiments of the present application, in the above apparatus, the negative sequence component determining unit 520 is configured to, if the operation mode of the converter is grid-connected operation, perform positive-negative sequence separation on the three-phase output voltage and the three-phase grid voltage of the converter respectively to obtain a negative sequence d-axis component of the grid voltage and a negative sequence q-axis component of the grid voltage, and obtain a negative sequence d-axis component of the output voltage and a negative sequence q-axis component of the output voltage as the voltage negative sequence control command, and use the negative sequence d-axis component of the output voltage and the negative sequence q-axis component of the output voltage as the voltage negative sequence; and the negative sequence d and q axis components of the modulation wave are obtained by PI control when the converter is connected with the grid and operates according to the voltage negative sequence control instruction and the voltage negative sequence control feedback.
In some embodiments of the present application, in the above apparatus, the negative sequence component determining unit 520 is configured to calculate a negative sequence d-axis component of the modulated wave and a negative sequence q-axis component of the modulated wave when the converter is in the off-grid operation by the following formulas:
wherein the content of the first and second substances,
is the negative sequence d-axis component of the modulated wave, 0 is the voltage negative sequence control command,
being the negative sequence d-axis component of the output voltage,
for the negative-sequence q-axis component of the modulated wave,
is the negative sequence q-axis component of the output voltage, G(s) is the proportional-integral regulator transfer function;
wherein the content of the first and second substances,
kP、kIfor conventional proportional integral regulator coefficients, s is a time-dependent function determined according to automatic control theory.
In some embodiments of the present application, in the above apparatus, the negative sequence component determining unit 520 is configured to calculate a negative sequence d-axis component of the modulated wave and a negative sequence q-axis component of the modulated wave when the converter is in grid-connected operation by the following formulas:
wherein the content of the first and second substances,
for the negative sequence d-axis component of the modulated wave,
being the negative sequence d-axis component of the grid voltage,
being the negative sequence d-axis component of the output voltage,
for the negative-sequence q-axis component of the modulated wave,
being the negative sequence q-axis component of the grid voltage,
is the negative sequence q-axis component of the output voltage, G(s) is the proportional-integral regulator transfer function;
wherein the content of the first and second substances,
kP、kIfor conventional proportional integral regulator coefficients, s is a time-dependent function determined according to automatic control theory.
In some embodiments of the present application, in the above apparatus, the power determining unit 510 is configured to determine the actual output power of the converter according to the following calculation formula:
wherein, PeActive power; q is reactive power; u. ofa、ub、ucThree-phase output voltages of the converter are respectively; i.e. ia、ib、icThree-phase currents of the converter are respectively; gc(s) is the transfer function of a second order low pass filter, GcThe formula for calculation of(s) is:
wherein, ω isnIs the natural angular frequency of the second order low pass filter, ξ is the damping coefficient of the second order low pass filter, and s is a time-dependent function determined according to the automatic control theory.
In some embodiments of the present application, in the above apparatus, the positive sequence component determining unit 530 is configured to determine a rotor angular frequency according to the active power and the active-frequency control model, and integrate the rotor angular frequency to obtain a coordinate transformation angle;
wherein, the active-frequency control model includes a rotor equation of motion and a prime mover equation of motion, wherein the rotor equation of motion is:
wherein, ω isNRated rotor angular frequency, omega rotor angular frequency; J. d is respectively a rotational inertia and a damping coefficient; pmIs mechanical power, PeActive power; delta is a power angle;
the prime mover regulation equation is:
Pm＝Pref+kf(ωN-ω)，
wherein, PrefAs an active power command, kfIs the active frequency modulation coefficient.
In some embodiments of the present application, in the aboveIn the above-mentioned device, the positive sequence component determination unit 530 is used for making the positive sequence d-axis component of the modulated wave be electromotive force EmElectromotive force EmDetermining according to a reactive power and a reactive-voltage control model, wherein the reactive-voltage control model is as follows:
wherein E ismIs electromotive force; qrefIs a reactive power command; u shapeNIs a nominal phase voltage amplitude; k is a reactive inertia coefficient; k is a radical ofvIs a reactive voltage regulation coefficient; q is reactive power; u shapemIs the voltage amplitude of the converter.
The device shown in fig. 5 can show that, aiming at the working conditions of unbalanced VSG off-grid load and unbalanced grid voltage, the voltage type VSG control device for the converter under the unbalanced working condition is provided, the control device has a simple calculation structure and small calculation amount, and can reduce the unbalanced degree of the off-grid output voltage and improve the capability of the VSG with the off-grid unbalanced load while ensuring the basic characteristics of the voltage type VSG; the unbalance degree of grid-connected current can be reduced, the fault ride-through capability during the unbalance of the grid voltage is realized, and the voltage and frequency support is provided for the system; compared with the VSG unbalance control method in the prior art, the VSG unbalance control method is suitable for various unbalance working conditions, simple and reliable in control structure, clear in system working operation mode and high in response speed; the problems of reducing the quality of electric energy, such as harmonic interference, current distortion, large-amplitude power oscillation and the like, are avoided, the service life of an electronic device is prolonged, and the reliability of the integral work of the converter is improved.
In some embodiments of the present application, the apparatus further comprises: the PCC point switch detection unit is used for detecting the state of the PCC point switch and determining the operation mode of the converter according to the state of the PCC point switch; determining that the operation mode of the converter is off-grid operation under the condition that the PCC point switch is in an off state; and under the condition that the PCC point switch is in a closed state, determining that the operation mode of the converter is grid-connected operation.
It should be noted that the apparatus 500 of the present application can implement the above-mentioned methods one by one, and the details are not repeated.
It should be noted that:
the algorithms and displays presented herein are not inherently related to any particular computer, virtual machine, or other apparatus. Various general purpose devices may be used with the teachings herein. The required structure for constructing such a device will be apparent from the description above. In addition, this application is not directed to any particular programming language. It will be appreciated that a variety of programming languages may be used to implement the teachings of the present application as described herein, and any descriptions of specific languages are provided above to disclose the best modes of the present application.
In the description provided herein, numerous specific details are set forth. However, it is understood that embodiments of the application may be practiced without these specific details. In some instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure an understanding of this description.
Similarly, it should be appreciated that in the foregoing description of exemplary embodiments of the application, various features of the application are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the application and aiding in the understanding of one or more of the various inventive aspects. However, the disclosed method should not be interpreted as reflecting an intention that: this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single foregoing disclosed embodiment. Thus, the claims following the detailed description are hereby expressly incorporated into this detailed description, with each claim standing on its own as a separate embodiment of this application.
Those skilled in the art will appreciate that the modules in the device in an embodiment may be adaptively changed and disposed in one or more devices different from the embodiment. The modules or units or components of the embodiments may be combined into one module or unit or component, and furthermore they may be divided into a plurality of sub-modules or sub-units or sub-components. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and all of the processes or elements of any method or apparatus so disclosed, may be combined in any combination, except combinations where at least some of such features and/or processes or elements are mutually exclusive. Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise.
Furthermore, those skilled in the art will appreciate that while some embodiments described herein include some features included in other embodiments, rather than other features, combinations of features of different embodiments are meant to be within the scope of the application and form different embodiments. For example, in the following claims, any of the claimed embodiments may be used in any combination.
The various component embodiments of the present application may be implemented in hardware, or in software modules running on one or more processors, or in a combination thereof. It will be appreciated by those skilled in the art that a microprocessor or Digital Signal Processor (DSP) may be used in practice to implement some or all of the functions of some or all of the components in the control arrangement of the current transformer according to embodiments of the present application. The present application may also be embodied as apparatus or device programs (e.g., computer programs and computer program products) for performing a portion or all of the methods described herein. Such programs implementing the present application may be stored on a computer readable medium or may be in the form of one or more signals. Such a signal may be downloaded from an internet website or provided on a carrier signal or in any other form.
For example, fig. 6 shows a schematic structural diagram of an electronic device according to an embodiment of the present application. The electronic device 600 comprises a processor 610 and a memory 620 arranged to store computer executable instructions (computer readable program code). The memory 620 may be an electronic memory such as a flash memory, an EEPROM (electrically erasable programmable read only memory), an EPROM, a hard disk, or a ROM. The memory 620 has a storage space 630 storing computer readable program code 631 for performing any of the method steps described above. For example, the memory space 630 for storing the computer readable program code may comprise respective computer readable program codes 631 for respectively implementing the various steps in the above method. The computer readable program code 631 may be read from or written to one or more computer program products. These computer program products comprise a program code carrier such as a hard disk, a Compact Disc (CD), a memory card or a floppy disk. Such a computer program product is typically a computer readable storage medium such as that shown in fig. 7. FIG. 7 shows a schematic diagram of a computer-readable storage medium according to an embodiment of the present application. The computer readable storage medium 700, in which a computer readable program code 631 for performing the method steps according to the application is stored, is readable by the processor 610 of the electronic device 600, which computer readable program code 631, when executed by the electronic device 600, causes the electronic device 600 to perform the respective steps of the method described above, in particular the computer readable program code 631 stored by the computer readable storage medium may perform the method shown in any of the embodiments described above. The computer readable program code 631 may be compressed in a suitable form.
It should be noted that the above-mentioned embodiments illustrate rather than limit the application, and that those skilled in the art will be able to design alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The word "comprising" does not exclude the presence of elements or steps not listed in a claim. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The application may be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In the unit claims enumerating several means, several of these means may be embodied by one and the same item of hardware. The usage of the words first, second and third, etcetera do not indicate any ordering. These words may be interpreted as names.
Claims (10)
1. A method for controlling a converter, comprising:
determining actual output power of the converter according to three-phase output voltage and three-phase current of the converter, wherein the actual output power comprises active power and reactive power;
determining a coordinate transformation angle according to the active power and active-frequency control model, and determining a positive sequence d-axis component of the modulated wave according to the reactive power and reactive-voltage control model, so that the positive sequence q-axis component of the modulated wave is fixed to be 0; wherein the active-frequency control model and the reactive-voltage control model are both obtained based on virtual synchronous machine (VSG) modeling;
determining a voltage negative sequence control instruction and voltage negative sequence control feedback according to the operation mode of the converter, and determining a negative sequence d-axis component of a modulated wave and a negative sequence q-axis component of the modulated wave according to the voltage negative sequence control instruction and the voltage negative sequence control feedback, so that the modulated wave under a dq-axis coordinate system is determined according to the positive sequence d-axis component of the modulated wave, the positive sequence q-axis component of the modulated wave, the negative sequence d-axis component of the modulated wave and the negative sequence q-axis component of the modulated wave;
and based on the coordinate transformation angle, carrying out coordinate transformation on the modulation wave in the dq axis coordinate system to obtain a modulation signal in an abc coordinate system, and driving the converter to work according to the modulation signal.
2. The method of claim 1, wherein determining a negative-sequence voltage control command and a negative-sequence voltage control feedback based on the operating mode of the converter, and determining a negative-sequence d-axis component of the modulated wave and a negative-sequence q-axis component of the modulated wave based on the negative-sequence voltage control command and the negative-sequence voltage control feedback, comprises:
if the operation mode of the converter is off-grid operation, making a voltage negative sequence control command be 0, and performing positive-negative sequence separation on three-phase output voltage of the converter to obtain a negative sequence d-axis component of the output voltage and a negative sequence q-axis component of the output voltage as voltage negative sequence control feedback;
and obtaining a negative sequence d-axis component of the modulation wave and a negative sequence q-axis component of the modulation wave when the converter is in off-grid operation through PI control according to the voltage negative sequence control command and the voltage negative sequence control feedback.
3. The method of claim 1, wherein determining a negative-sequence voltage control command and a negative-sequence voltage control feedback based on the operating mode of the converter, and determining a negative-sequence d-axis component of the modulated wave and a negative-sequence q-axis component of the modulated wave based on the negative-sequence voltage control command and the negative-sequence voltage control feedback, comprises:
if the operation mode of the converter is grid-connected operation, respectively carrying out positive and negative sequence separation on three-phase output voltage and three-phase power grid voltage of the converter to obtain a negative sequence d-axis component of the power grid voltage and a negative sequence q-axis component of the power grid voltage, and using the negative sequence d-axis component of the output voltage and the negative sequence q-axis component of the output voltage as a voltage negative sequence control instruction to obtain a negative sequence d-axis component of the output voltage and a negative sequence q-axis component of the output voltage as voltage negative sequence control feedback;
and obtaining a negative sequence d-axis component of the modulation wave and a q-axis component of the modulation wave when the converter is connected to the grid and operates through PI control according to the voltage negative sequence control command and the voltage negative sequence control feedback.
4. The method according to claim 2, wherein obtaining a negative sequence d-axis component of a modulated wave and a negative sequence q-axis component of the modulated wave when the converter is in off-grid operation through PI control according to the negative voltage sequence control command and the negative voltage sequence control feedback comprises:
calculating the negative sequence d-axis component of the modulating wave and the negative sequence q-axis component of the modulating wave when the converter runs off the grid by the following formula:
wherein the content of the first and second substances,
is the negative sequence d-axis component of the modulated wave, 0 is the voltage negative sequence control command,
being the negative sequence d-axis component of the output voltage,
for the negative-sequence q-axis component of the modulated wave,
is the negative sequence q-axis component of the output voltage, G(s) is the proportional-integral regulator transfer function;
wherein the content of the first and second substances,
kP、kIfor conventional proportional integral regulator coefficients, s is a time-dependent function determined according to automatic control theory.
5. The method according to claim 3, wherein obtaining a negative sequence d-axis component of a modulation wave and a q-axis component of the modulation wave during grid-connected operation of the converter through PI control according to the negative voltage sequence control command and the negative voltage sequence control feedback comprises:
calculating a negative sequence d-axis component of a modulation wave and a negative sequence q-axis component of the modulation wave when the converter is in grid-connected operation by the following formula:
wherein the content of the first and second substances,
for the negative sequence d-axis component of the modulated wave,
being the negative sequence d-axis component of the grid voltage,
being the negative sequence d-axis component of the output voltage,
for the negative-sequence q-axis component of the modulated wave,
being the negative sequence q-axis component of the grid voltage,
is the negative sequence q-axis component of the output voltage, G(s) is the proportional-integral regulator transfer function;
wherein the content of the first and second substances,
kP、kIfor conventional proportional integral regulator coefficients, s is a time-dependent function determined according to automatic control theory.
6. The method of claim 1, wherein determining the actual output power of the converter from the three phase output voltages and the three phase currents of the converter comprises:
determining the actual output power of the converter according to the following calculation formula:
wherein, PeActive power; q is reactive power; u. ofa、ub、ucThree-phase output voltages of the converter are respectively; i.e. ia、ib、icThree-phase currents of the converter are respectively; gc(s) is the transfer function of a second order low pass filter, GcThe formula for calculation of(s) is:
wherein, ω isnIs the natural angular frequency of the second order low pass filter, ξ is the damping coefficient of the second order low pass filter, and s is a time-dependent function determined according to the automatic control theory.
7. The method of claim 1, wherein determining a coordinate transformation angle from the active power and active-frequency control model comprises:
determining the rotor angular frequency according to the active power and the active-frequency control model, and integrating the rotor angular frequency to obtain the coordinate transformation angle;
wherein the active-frequency control model comprises a rotor motion equation and a prime mover regulation equation, wherein the rotor motion equation is:
wherein, ω isNRated rotor angular frequency, omega rotor angular frequency; J. d is respectively a rotational inertia and a damping coefficient; pmIs mechanical power, PeActive power; delta is a power angle;
the prime mover regulation equation is:
Pm＝Pref+kf(ωN-ω)，
wherein, PrefAs an active power command, kfIs the active frequency modulation coefficient.
8. The method of claim 1, wherein determining a positive sequence d-axis component of a modulated wave from the reactive power and reactive-voltage control model comprises:
making the positive sequence d-axis component of the modulated wave as electromotive force EmElectromotive force EmDetermining according to the reactive power and a reactive-voltage control model, wherein the reactive-voltage control model is:
wherein E ismIs electromotive force; qrefIs a reactive power command; u shapeNIs a nominal phase voltage amplitude; k is a reactive inertia coefficient; k is a radical ofvIs a reactive voltage regulation coefficient; q is reactive power; u shapemIs the voltage amplitude of the converter.
9. A control apparatus for a converter, comprising:
the power determining unit is used for determining the actual output power of the converter according to the three-phase output voltage and the three-phase current of the converter, wherein the actual output power comprises active power and reactive power;
the positive sequence component determining unit is used for determining a coordinate transformation angle according to the active power and active-frequency control model, determining a positive sequence d-axis component of the modulating wave according to the reactive power and reactive-voltage control model, and fixing a positive sequence q-axis component of the modulating wave to be 0; wherein the active-frequency control model and the reactive-voltage control model are both obtained based on virtual synchronous machine (VSG) modeling;
the negative sequence component determining unit is used for determining a voltage negative sequence control command and voltage negative sequence control feedback according to the operation mode of the converter, and determining a negative sequence d-axis component of a modulating wave and a negative sequence q-axis component of the modulating wave according to the voltage negative sequence control command and the voltage negative sequence control feedback, so that the modulating wave under a dq-axis coordinate system is determined according to the positive sequence d-axis component of the modulating wave, the positive sequence q-axis component of the modulating wave, the negative sequence d-axis component of the modulating wave and the negative sequence q-axis component of the modulating wave;
and the coordinate transformation unit is used for carrying out coordinate transformation on the modulation wave in the dq axis coordinate system based on the coordinate transformation angle to obtain a modulation signal in an abc coordinate system, so as to drive the converter to work according to the modulation signal.
10. A converter comprising the converter control apparatus of claim 9.
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| 乔仁飞: "基于虚拟同步发电机的光伏系统低电压穿越技术研究", 《CNKI优秀硕士学位论文全文数据库》 * |
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| CN112968452B (en) | 2022-11-29 |
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