CN113158416A - Modeling method and device for modular multilevel converter and storage medium - Google Patents

Modeling method and device for modular multilevel converter and storage medium Download PDF

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CN113158416A
CN113158416A CN202110203709.1A CN202110203709A CN113158416A CN 113158416 A CN113158416 A CN 113158416A CN 202110203709 A CN202110203709 A CN 202110203709A CN 113158416 A CN113158416 A CN 113158416A
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mmc
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bridge arm
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sub
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陈盛燃
万敏
何建宗
郑风雷
夏云峰
魏炯辉
钟荣富
何文志
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Guangdong Power Grid Co Ltd
Dongguan Power Supply Bureau of Guangdong Power Grid Co Ltd
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Dongguan Power Supply Bureau of Guangdong Power Grid Co Ltd
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Abstract

The invention discloses a modeling method and device for a modular multilevel converter and a storage medium. A modeling method of a modular multilevel converter comprises the following steps: determining a differential mode component and a common mode component of the capacitance voltage of the submodule in the MMC time domain; transforming the differential mode component and the common mode component to a dq coordinate system; carrying out linearization processing on the converted differential mode component and common mode component to obtain an MMC submodule capacitor voltage s-domain small signal model; obtaining an MMC unbalanced active power linearization model and a MMC direct-current side voltage linearization model according to the dynamic characteristics of the MMC sub-modules; obtaining a mathematical model of the MMC dynamically established according to the voltage of the MMC sub-module according to the MMC vector control strategy; and establishing a motion equation model of the MMC according to the mathematical model of the MMC. The modeling method, the modeling device and the storage medium of the modular multilevel converter disclosed by the embodiment of the invention have universality and universality, and are beneficial to analysis of MMC.

Description

Modeling method and device for modular multilevel converter and storage medium
Technical Field
The invention relates to the technical field of electric power, in particular to a modeling method and device of a modular multilevel converter and a storage medium.
Background
Modular Multilevel Converters (MMC) have the advantages of high modularization degree, good output waveform quality, low loss and the like, become the most competitive Converter topology in a flexible direct-current transmission system, and are also applied to medium-high voltage power electronic transformers.
The system stability problem based on the MMC topology is researched, and the method has important significance for guaranteeing safe and stable operation of the power system. For the research of the MMC topology, modeling needs to be carried out on the MMC topology firstly, but the current modeling method for the MMC is not accurate enough, the modeling method is too mathematical and has unknown physical significance, and the stability research on the MMC topology is influenced. Therefore, how to abstract a physical model which is easy to understand the dynamic mechanism of the MMC from the existing mathematical model of the MMC is the key for analyzing and solving the system stability problem.
Disclosure of Invention
The invention provides a modeling method and device of a modular multilevel converter and a storage medium, which have universality and are beneficial to analysis of an MMC.
In a first aspect, an embodiment of the present invention provides a modeling method for a modular multilevel converter, including:
determining a differential mode component and a common mode component of the capacitance voltage of the submodule in the MMC time domain;
transforming the differential mode component and the common mode component to a dq coordinate system;
carrying out linearization processing on the converted differential mode component and common mode component to obtain an MMC submodule capacitor voltage s-domain small signal model;
obtaining an MMC unbalance active power linearization model according to the dynamic characteristics of the MMC sub-modules;
obtaining a linear model of the voltage of the MMC direct current side according to the dynamic characteristics of the MMC sub-modules;
obtaining a mathematical model of the MMC according to an MMC vector control strategy, wherein the mathematical model is dynamically established according to the voltage of a submodule of the MMC;
and establishing a motion equation model of the MMC according to the mathematical model of the MMC.
In a possible implementation manner of the first aspect, determining a differential-mode component and a common-mode component of a sub-module capacitor voltage in an MMC time domain includes:
according to the formula
Figure BDA0002948964550000021
Determining a differential mode component of the capacitance voltage of the submodule in the MMC time domain;
wherein C isarmEquivalent sub-module capacitance, C, for one bridge armarmC is the capacitance value of each submodule, N is the number of submodules of each bridge arm,
Figure BDA0002948964550000022
is the differential mode component of the bridge arm output voltage,
Figure BDA0002948964550000023
for the common-mode component of the bridge arm modulation function,
Figure BDA0002948964550000024
for the differential-mode component of the bridge arm modulation function,
Figure BDA0002948964550000025
is the common-mode component of the bridge arm currents,
Figure BDA0002948964550000026
is the differential-mode component of the bridge arm current,
Figure BDA0002948964550000027
is the internal potential of the inverter and,
Figure BDA0002948964550000028
ucjpfor the upper bridge arm to output voltage ucjnOutputting voltage for a lower bridge arm;
according to the formula
Figure BDA0002948964550000029
Determining a common-mode component of the capacitance voltage of the submodule in the MMC time domain;
wherein the content of the first and second substances,
Figure BDA00029489645500000210
is the common-mode component of the bridge arm output voltage,
Figure BDA00029489645500000211
ucjpfor the upper arm outputting voltage ucjnAnd outputting voltage for the lower bridge arm.
In a possible implementation manner of the first aspect, transforming the differential-mode component and the common-mode component to a dq coordinate system includes:
the differential and common mode components are transformed to the dq coordinate system using a dq transformation matrix P as follows:
Figure BDA0002948964550000031
the sub-module capacitor voltage differential mode component after dq conversion is
Figure BDA0002948964550000032
Wherein:
Figure BDA0002948964550000033
is the d-axis component of the differential-mode component of the sub-module capacitance voltage,
Figure BDA0002948964550000034
q-axis component, ω, of differential-mode component of sub-module capacitor voltage1For the fundamental angular frequency of the ac system,
Figure BDA0002948964550000035
for the d-axis component of the bridge arm differential mode modulation current,
Figure BDA0002948964550000036
modulating a q-axis component of the current for the bridge arm differential mode;
Figure BDA0002948964550000037
the common mode component of the sub-module capacitor voltage after dq conversion is
Figure BDA0002948964550000038
Wherein:
Figure BDA0002948964550000039
is the d-axis component of the common mode component of the sub-module capacitor voltage,
Figure BDA00029489645500000310
being the q-axis component of the common mode component of the sub-module capacitor voltage,
Figure BDA00029489645500000311
is a direct current component in the common mode component of the sub-module capacitor voltage,
Figure BDA00029489645500000312
is the d-axis component of the bridge arm common mode modulation current,
Figure BDA00029489645500000313
for the q-axis component of the bridge arm common mode modulation current,
Figure BDA00029489645500000314
modulating the direct current component of the current for the common mode of the bridge arms;
Figure BDA00029489645500000315
wherein the content of the first and second substances,
Figure BDA00029489645500000316
is the dc component of the MMC bridge arm common mode current,
Figure BDA00029489645500000317
for the d-axis component of the MMC bridge arm common mode current,
Figure BDA00029489645500000318
for the q-axis component of the MMC bridge arm common mode current,
Figure BDA00029489645500000319
is the d-axis component of the differential mode current of the MMC bridge arm,
Figure BDA00029489645500000320
for the q-axis component of the MMC bridge arm differential mode current,
Figure BDA00029489645500000321
for the dc component of the MMC bridge arm common mode modulation function,
Figure BDA0002948964550000041
for the MMC bridge arm common mode modulation function d-axis component,
Figure BDA0002948964550000042
for the q-axis component of the MMC bridge arm common mode modulation function,
Figure BDA0002948964550000043
is the d-axis component of the differential mode current of the MMC bridge arm,
Figure BDA0002948964550000044
q-axis component, omega, of differential mode current of bridge arm of MMC1Is the fundamental angular frequency of the ac system.
In a possible implementation manner of the first aspect, an s-domain small signal model after a differential mode component of a sub-module capacitor voltage is subjected to linearization processing is as follows:
Figure BDA0002948964550000045
the s-domain small signal model of the common-mode component of the sub-module capacitor voltage after linearization processing is as follows:
Figure BDA0002948964550000046
where s is the laplace operator.
In a possible implementation manner of the first aspect, obtaining an MMC unbalanced active power linearization model according to a dynamic characteristic of an MMC sub-module includes:
using the formula
Figure BDA0002948964550000047
Obtaining an MMC unbalance active power linearization model, wherein, delta PdcRepresenting the unbalanced power, Δ Pdc＝ΔPin-ΔP，PinRepresents the input power of the direct current side, and P represents the output power of the alternating current side;
transfer function G1(s), transfer function G2(s), transfer function G3(s) are respectively:
Figure BDA0002948964550000048
Figure BDA0002948964550000051
wherein the content of the first and second substances,
Figure BDA0002948964550000052
is the steady-state component of the d-axis component of the common-mode component of the sub-module capacitor voltage,
Figure BDA0002948964550000053
is the steady-state component of the q-axis component of the common-mode component of the sub-module capacitance voltage,
Figure BDA0002948964550000054
is a steady-state component of the dc component of the common-mode component of the sub-module capacitor voltages,
Figure BDA0002948964550000055
is the steady state component of the d-axis component of the differential mode component of the sub-module capacitance voltage,
Figure BDA0002948964550000056
is the steady-state component of the q-axis component of the differential-mode component of the sub-module capacitor voltage,
Figure BDA0002948964550000057
is the steady-state component of the dc component of the MMC bridge arm common mode modulation function,
Figure BDA0002948964550000058
is a steady-state component of the MMC bridge arm common-mode modulation function d-axis component,
Figure BDA0002948964550000059
is the steady-state component of the q-axis component of the MMC bridge arm common-mode modulation function,
Figure BDA00029489645500000510
is a steady-state component of the d-axis component of the differential-mode current of the MMC bridge arm,
Figure BDA00029489645500000511
the component is a steady-state component of a q-axis component of the MMC bridge arm differential mode current.
In a possible implementation manner of the first aspect, obtaining a linear model of the voltage at the dc side of the MMC according to the dynamic characteristic of the MMC sub-module includes:
using the formula
Figure BDA00029489645500000512
Obtaining a linear model of the DC side voltage of the MMC, wherein the transfer function Z1(s), transfer function Z2(s), transfer function Z3(s) are respectively:
Figure BDA00029489645500000513
Figure BDA00029489645500000514
Figure BDA00029489645500000515
wherein, Udc0Is a steady-state component of the dc side voltage,
Figure BDA00029489645500000516
is the steady-state component of the bridge arm common mode current direct current component.
In a possible implementation manner of the first aspect, establishing an equation of motion model of the MMC according to a mathematical model of the MMC includes:
solving an equivalent inertia coefficient and a damping coefficient in an MMC motion equation according to a mathematical model of the MMC;
and establishing an MMC motion equation model according to the equivalent inertia coefficient and the damping coefficient in the MMC motion equation.
In a possible implementation manner of the first aspect, solving an equivalent inertia coefficient and a damping coefficient in an MMC equation of motion according to a mathematical model of the MMC includes:
solving an equivalent inertia coefficient M(s) and a damping coefficient D(s) of the MMC according to the following formula:
Figure BDA0002948964550000061
wherein
Figure BDA0002948964550000062
In a second aspect, an embodiment of the present invention provides a modeling apparatus for a modular multilevel converter, including:
the voltage component determining module is used for determining a differential mode component and a common mode component of the capacitance voltage of the submodule in the MMC time domain;
a coordinate transformation module for transforming the differential mode component and the common mode component into a dq coordinate system;
the linearization processing module is used for carrying out linearization processing on the converted differential mode component and the converted common mode component to obtain an MMC sub-module capacitance voltage s-domain small signal model; obtaining an MMC unbalance active power linearization model according to the dynamic characteristics of the MMC sub-modules; obtaining a linear model of the voltage of the MMC direct current side according to the dynamic characteristics of the MMC sub-modules;
the model establishing module is used for obtaining a mathematical model of the MMC according to the MMC vector control strategy, and the mathematical model is dynamically established according to the voltage of the MMC sub-module; and establishing a motion equation model of the MMC according to the mathematical model of the MMC.
In a third aspect, an embodiment of the present invention provides a computer-readable storage medium, on which a computer program is stored, where the computer program, when executed by a processor, implements the modeling method for a modular multilevel converter according to any implementation manner of the first aspect.
The modeling method, the modeling device and the storage medium of the modular multilevel converter provided by the embodiment of the invention firstly determine a differential mode component and a common mode component of a sub-module capacitance voltage in an MMC time domain, then convert the differential mode component and the common mode component into a dq coordinate system, and carry out linearization processing on the converted differential mode component and the common mode component to obtain an MMC sub-module capacitance voltage s-domain small signal model, then respectively obtain an MMC unbalanced active power linearization model and a MMC direct-current side voltage linearization model according to the dynamic characteristics of the MMC sub-module, and finally obtain a mathematical model of the MMC according to an MMC vector control strategy, wherein the mathematical model is dynamically established according to the MMC sub-module voltage, and a motion equation model of the MMC is established according to the mathematical model of the MMC, and the modeling method of the modular multilevel converter provided by the embodiment has universality and universality, the MMC analysis is facilitated.
Drawings
Fig. 1 is a flowchart of a modeling method of a modular multilevel converter according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of an MMC mathematical model according to MMC sub-module voltage dynamics;
FIG. 3 is a schematic diagram of an MMC direct-current voltage time scale equation of motion;
FIGS. 4 a-4 d are schematic diagrams of MMC model verification;
FIG. 5 is a schematic structural diagram of an MMC converter connected to an infinite power grid;
FIG. 6 is a schematic diagram of an MMC direct-current voltage time scale closed-loop equation of motion;
FIG. 7 is a diagram of a dynamic analysis of potential phase within the time scale of the MMC DC voltage;
FIG. 8 is a block diagram of a dynamic analysis of the magnitude of the potential within the time scale of the MMC DC voltage;
FIG. 9a is ki3The MMC direct-current voltage time scale inertia changes along with the frequency under the change;
FIG. 9b is ki3The MMC direct-current voltage time scale damping changes with the frequency under the change;
FIG. 10a is kp3The MMC direct-current voltage time scale inertia changes along with the frequency under the change;
FIG. 10b is kp3The MMC direct-current voltage time scale damping changes with the frequency under the change;
FIG. 11 shows the dynamic response of active power for different PLL parameters;
fig. 12 is a schematic structural diagram of a modular multilevel converter modeling apparatus according to an embodiment of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It is to be further noted that, for the convenience of description, only a part of the structure relating to the present invention is shown in the drawings, not the whole structure.
Fig. 1 is a flowchart of a modeling method for a modular multilevel converter according to an embodiment of the present invention, and as shown in fig. 1, the modeling method for a modular multilevel converter according to the embodiment includes:
step S101, determining differential mode components and common mode components of capacitance and voltage of the sub-modules in the MMC time domain.
The modeling method of the modular multilevel converter provided by the embodiment is used for modeling an MMC. The existing MMC modeling method has the following problems: 1. the modeling method for ignoring the dynamic state of the sub-modules is not accurate enough and is only suitable for system-level analysis; 2. the modeling method considering the submodule dynamics is over-mathematical, the physical meaning is not clear, and the abstraction of object physics, chemistry and functionalization is lacked; 3. the dynamics of a plurality of time scales are considered, and the pertinence is lacked; 4. physical equipment is not isolated from a system network, and universality are not realized.
In order to solve the defects of the existing MMC modeling method, the embodiment provides a modeling method of MMC direct-current voltage time scale based on an equation of motion, so as to solve the problems of unclear physical meaning, weak pertinence and no universality of the existing MMC modeling method.
Firstly, the differential mode component and the common mode component of the capacitance voltage of the submodule in the MMC time domain need to be determined. Namely, under the condition of considering fundamental frequency and double frequency fluctuation of the sub-module capacitor voltage, the differential mode component and the common mode component of the sub-module capacitor voltage in the time domain are obtained.
In particular, it can be based on a formula
Figure BDA0002948964550000091
Determining the differential mode component of the sub-module capacitance voltage in the MMC time domain according to a formula
Figure BDA0002948964550000092
And determining the common-mode component of the sub-module capacitor voltage in the MMC time domain.
Wherein C isarmBeing a bridge arm or the likeEffective module capacitance, CarmC is the capacitance value of each submodule, N is the number of submodules of each bridge arm,
Figure BDA0002948964550000093
is the differential mode component of the bridge arm output voltage,
Figure BDA0002948964550000094
for the common-mode component of the bridge arm modulation function,
Figure BDA0002948964550000095
for the differential-mode component of the bridge arm modulation function,
Figure BDA0002948964550000096
is the common-mode component of the bridge arm currents,
Figure BDA0002948964550000097
is the differential-mode component of the bridge arm current,
Figure BDA0002948964550000098
is the internal potential of the inverter and,
Figure BDA0002948964550000099
ucjpfor the upper bridge arm to output voltage ucjnOutputting voltage for a lower bridge arm;
Figure BDA00029489645500000910
is the common-mode component of the bridge arm output voltage,
Figure BDA00029489645500000911
ucjpfor the upper bridge arm to output voltage ucjnAnd outputting voltage for the lower bridge arm.
Step S102, the differential mode component and the common mode component are transformed to a dq coordinate system.
That is, the common mode component and the differential mode component of the sub-module capacitor voltage determined in step S101 are transformed into dq coordinate system by using dq transformation matrix. The dq transformation projects the a, b and c three-phase currents of the stator to a direct axis (d axis) and a quadrature axis (q axis) rotating along with the rotor and a zero axis (0 axis) perpendicular to a dq plane, so that the diagonalization of a stator inductance matrix is realized, and the operation analysis of the synchronous motor is simplified.
Specifically, the differential and common mode components can be transformed to the dq coordinate system using a dq transformation matrix P as follows:
Figure BDA0002948964550000101
the sub-module capacitor voltage differential mode component after dq conversion is
Figure BDA0002948964550000102
Wherein:
Figure BDA0002948964550000103
is the d-axis component of the differential-mode component of the sub-module capacitance voltage,
Figure BDA0002948964550000104
q-axis component, ω, of differential-mode component of sub-module capacitor voltage1For the fundamental angular frequency of the ac system,
Figure BDA0002948964550000105
for the d-axis component of the bridge arm differential mode modulation current,
Figure BDA0002948964550000106
the q-axis component of the current is modulated for the bridge arm differential mode.
Figure BDA0002948964550000107
The common mode component of the sub-module capacitor voltage after dq conversion is
Figure BDA0002948964550000108
Wherein:
Figure BDA0002948964550000109
is the d-axis component of the common mode component of the sub-module capacitor voltage,
Figure BDA00029489645500001010
being the q-axis component of the common mode component of the sub-module capacitor voltage,
Figure BDA00029489645500001011
is a direct current component in the common mode component of the sub-module capacitor voltage,
Figure BDA00029489645500001012
is the d-axis component of the bridge arm common mode modulation current,
Figure BDA00029489645500001013
for the q-axis component of the bridge arm common mode modulation current,
Figure BDA00029489645500001014
the DC component of the current is modulated in a common mode for the bridge arms.
Figure BDA0002948964550000111
Wherein the content of the first and second substances,
Figure BDA0002948964550000112
is the dc component of the MMC bridge arm common mode current,
Figure BDA0002948964550000113
for the d-axis component of the MMC bridge arm common mode current,
Figure BDA0002948964550000114
the q-axis component of the MMC bridge arm common mode current is obtained;
Figure BDA0002948964550000115
is the d-axis component of the differential mode current of the MMC bridge arm,
Figure BDA0002948964550000116
for the q-axis component of the MMC bridge arm differential mode current,
Figure BDA0002948964550000117
for the dc component of the MMC bridge arm common mode modulation function,
Figure BDA0002948964550000118
for the MMC bridge arm common mode modulation function d-axis component,
Figure BDA0002948964550000119
the q-axis component of the MMC bridge arm common mode modulation function is obtained;
Figure BDA00029489645500001110
is the d-axis component of the differential mode current of the MMC bridge arm,
Figure BDA00029489645500001111
q-axis component, omega, of differential mode current of bridge arm of MMC1Is the fundamental angular frequency of the ac system.
And step S103, carrying out linearization processing on the converted differential mode component and common mode component to obtain an MMC sub-module capacitance voltage S-domain small signal model.
The s-domain is that in frequency domain analysis, an imaginary exponent exp (j ω t) is used as a basic signal, an arbitrary signal can be decomposed into a plurality of imaginary exponent components with different frequencies, the zero state response of a linear time-invariant system (LTI system) is the integral (laplace transform) of the response caused by each component of an input signal, and the zero input response of the system can be simultaneously obtained by considering the initial state of the system, so that the full response of the system is obtained.
Specifically, an s-domain small signal model after the differential mode component of the sub-module capacitor voltage is subjected to linearization processing is as follows:
Figure BDA00029489645500001112
the s-domain small signal model of the common-mode component of the sub-module capacitor voltage after linearization processing is as follows:
Figure BDA0002948964550000121
where s is the laplace operator.
And step S104, obtaining an MMC unbalance active power linear model according to the dynamic characteristics of the MMC sub-modules.
When modeling the MMC, firstly, an unbalanced active power linearization model of the MMC and a linearization model of the dc side voltage of the converter need to be established. The MMC imbalance active power linearization model and the linearization model of the direct-current side voltage of the converter are both established according to the dynamic characteristics of the MMC sub-modules.
In particular, a formula may be used
Figure BDA0002948964550000122
Obtaining an MMC unbalance active power linearization model, wherein, delta PdcRepresenting the unbalanced power, Δ Pdc＝ΔPin-ΔP，PinRepresenting the input power of a direct current side, and P representing the output power of an alternating current side;
transfer function G1(s), transfer function G2(s), transfer function G3(s) are respectively:
Figure BDA0002948964550000123
Figure BDA0002948964550000124
Figure BDA0002948964550000125
wherein the content of the first and second substances,
Figure BDA0002948964550000131
for common-mode component of sub-module capacitor voltageThe steady-state component of the d-axis component,
Figure BDA0002948964550000132
is the steady-state component of the q-axis component of the common-mode component of the sub-module capacitance voltage,
Figure BDA0002948964550000133
is a steady-state component of the dc component of the common-mode component of the sub-module capacitor voltages,
Figure BDA0002948964550000134
is the steady state component of the d-axis component of the differential mode component of the sub-module capacitance voltage,
Figure BDA0002948964550000135
is the steady-state component of the q-axis component of the differential-mode component of the sub-module capacitor voltage,
Figure BDA0002948964550000136
is the steady-state component of the dc component of the MMC bridge arm common mode modulation function,
Figure BDA0002948964550000137
is a steady-state component of the MMC bridge arm common-mode modulation function d-axis component,
Figure BDA0002948964550000138
is the steady-state component of the q-axis component of the MMC bridge arm common-mode modulation function,
Figure BDA0002948964550000139
is a steady-state component of the d-axis component of the differential-mode current of the MMC bridge arm,
Figure BDA00029489645500001310
the component is a steady-state component of a q-axis component of the MMC bridge arm differential mode current.
And step S105, obtaining a linear model of the voltage at the direct current side of the MMC according to the dynamic characteristics of the MMC sub-module.
In particular, using the formula
Figure BDA00029489645500001311
Obtaining a linear model of the DC side voltage of the MMC, wherein the transfer function Z1(s), transfer function Z2(s), transfer function Z3(s) are respectively:
Figure BDA00029489645500001312
Figure BDA00029489645500001313
Figure BDA00029489645500001314
wherein, Udc0Is a steady-state component of the dc side voltage,
Figure BDA00029489645500001315
is the steady-state component of the bridge arm common mode current direct current component.
And S106, obtaining a mathematical model of the MMC according to the MMC vector control strategy, wherein the mathematical model is dynamically established according to the voltage of the MMC sub-module.
Fig. 2 is a schematic diagram of an MMC mathematical model according to voltage dynamics of an MMC submodule, and since the modeling method provided in this embodiment considers a time scale of a dc voltage loop, it considers that a current loop reacts fast enough, and can ignore the dynamics of the current loop, and considers that an actual current value is always equal to a command value thereof. Wherein: q is a reactive control instruction, XeqIs an equivalent reactance on the AC side, UtFor the AC mains voltage, E is the amplitude of the internal potential of the converter, theta is the phase of the internal potential of the converter, thetatFor the phase of the AC mains voltage, thetapIs the output phase of the phase locked loop. PI (proportional integral)1Is a voltage outer loop controller, the transfer function of which is: k is a radical ofp1+ki1S, where k isp1Is the proportional coefficient of the controller, ki1Is the integral coefficient of the controller; PI (proportional integral)2Is a reactive outer-loop controller, and is provided with a reactive outer-loop controller,the transfer function is: k is a radical ofp2+ki2S, where k isp2Is the proportional coefficient of the controller, ki2Is the integral coefficient of the controller; PI (proportional integral)3Is a phase locked loop controller, the transfer function of which is: k is a radical ofp3+ki3S, where k isp3Is the proportional coefficient of the controller, ki3Is the integral coefficient of the controller.
And step S107, establishing a motion equation model of the MMC according to the mathematical model of the MMC.
After the mathematical model of the MMC shown in fig. 2 is obtained, the corresponding coefficient of the MMC can be obtained from the mathematical model, so that the motion equation model of the MMC is established.
In an embodiment, the equivalent inertia coefficient and the damping coefficient in the motion equation of the MMC can be solved according to the mathematical model of the MMC, and then the motion equation model of the MMC is established according to the equivalent inertia coefficient and the damping coefficient in the motion equation of the MMC.
The equivalent inertia coefficient M(s) and the damping coefficient D(s) of the MMC can be solved according to the following formula:
Figure BDA0002948964550000141
wherein
Figure BDA0002948964550000142
Furthermore, the method for extracting the equivalent inertia coefficient and the damping coefficient in the MMC comprises the following steps:
neglecting the dynamics of the input active, assuming a known unbalanced power Δ PdcThe transfer function with phase Δ θ is:
Figure BDA0002948964550000151
the transfer function g(s) may be further processed as follows:
Figure BDA0002948964550000152
wherein, the coefficients of the numerator and the denominator are respectively as follows:
Figure BDA0002948964550000153
the purpose of this step is to make the denominator of the transfer function g(s) contain only the even term of s, and then to divide the transfer function g(s) into two parts, as follows:
Figure BDA0002948964550000154
in this case, the first part of the numerator of the transfer function g(s) contains only even terms of s and the second part of the numerator contains only odd terms of s. Wherein x is the largest even number in the range of 0 to m + n, and y is the largest odd number in the range of 0 to m + n. Extracting the first part for 1/s2And (4) extracting 1/s from the second part, wherein the numerator and the denominator of the rest part only contain even terms of s. At this moment, simulating the inertia and damping coefficient of the synchronous motor, the equivalent inertia coefficient and damping coefficient of the MMC direct-current voltage time scale can be obtained as follows:
Figure BDA0002948964550000161
by the method, the equivalent inertia M(s) and the damping coefficient D(s) of the MMC can be obtained, and then the MMC mathematical model shown in FIG. 2 can be converted into the form of the motion equation shown in FIG. 3. FIG. 3 is a schematic diagram of an MMC direct-current voltage time scale motion equation.
The modeling method of the modular multilevel converter provided by the embodiment decouples the characteristics of the MMC equipment and an external network, and due to the characteristic, the model is easy to expand into multi-machine analysis and can be popularized to modeling of other equipment, so that the modeling method has universality and universality. Secondly, the analysis of the physical meaning of the MMC model and the dynamic process of the system is facilitated to be explained due to the fact that the MMC model is based on the motion equation. Finally, the influence of different system parameters on the equivalent inertia and the damping embodied by the MMC can be analyzed through the modeling method provided by the embodiment, so that the equivalent inertia and the damping embodied by the MMC can be changed by optimizing the parameters of the controller, and the system stability is improved.
The modeling method of the modular multilevel converter provided by this embodiment first determines the differential mode component and the common mode component of the capacitance voltage of the sub-module in the time domain of the MMC, then converting the differential mode component and the common mode component into a dq coordinate system, and carrying out linearization processing on the converted differential mode component and the converted common mode component to obtain an MMC sub-module capacitance voltage s-domain small signal model, then obtaining an MMC unbalanced active power linearization model and a MMC direct-current side voltage linearization model according to the dynamic characteristics of the MMC sub-modules, finally obtaining a mathematical model of the MMC according to an MMC vector control strategy, dynamically establishing the mathematical model according to the voltage of the MMC sub-modules, the modeling method of the modular multilevel converter provided by the embodiment has universality and universality, and is beneficial to analysis of the MMC.
The modeling method of the modular multilevel converter provided by the embodiment of the invention is explained in detail by using a specific embodiment.
In a first application scenario, the parameters of the main circuit of the MMC current converter are shown in table 1, and table 1 is a schematic table of the parameters of the main circuit and the controller of the MMC current converter.
TABLE 1
Figure BDA0002948964550000171
And verifying the dynamic response of the established model under small disturbance, setting the phase jump 10 degrees of the power grid voltage at the moment when the time t is 4s, and comparing the dynamic response of the active power, the reactive power, the phase and the amplitude of the terminal voltage of the motion equation model provided by the detailed model and the embodiment of the invention, as shown in fig. 4 a-4 b. Fig. 4 a-4 d are schematic diagrams of MMC model verification, wherein fig. 4a is a schematic diagram of an active power response, fig. 4b is a schematic diagram of a reactive power response, fig. 4c is a schematic diagram of an internal potential phase dynamic response, and fig. 4d is a schematic diagram of an internal potential amplitude dynamic response.
In fig. 4 a-4 d, the dotted line represents a detailed simulation model, and the solid line represents a motion equation model established by the modeling method provided by the embodiment of the invention. As can be seen from fig. 4a to 4d, when a small disturbance occurs to the ac-side power grid, the active power, the reactive power, the internal potential phase and the amplitude of the detailed mathematical model and the equation of motion model are well matched, that is, the established MMC model can accurately reflect the dynamic characteristics of the converter, and the model is verified to be effective.
In a second application scenario, the mechanism of the phase dynamics of the internal potential is analyzed. Assuming that the MMC is connected to an infinite power grid, fig. 5 is a schematic structural diagram of the MMC converter connected to the infinite power grid.
In FIG. 5, E is the amplitude of the internal potential on the AC side of the MMC, θ is the phase of the internal potential on the AC side of the MMC, and XeqIs an MMC bridge arm equivalent reactance, UtIs the magnitude of the PCC point voltage, θtIs the phase of the PCC point voltage, XgFor equivalent reactance of the grid, UgIs the magnitude of the grid voltage.
According to the equation of work angle, the MMC direct-current voltage time scale motion equation shown in fig. 3 can be converted into a closed-loop motion equation structure shown in fig. 6, and fig. 6 is a schematic diagram of the MMC direct-current voltage time scale closed-loop motion equation.
Functional relationship K between active power and internal potential phase in FIG. 6PθAnd the functional relationship K between the active power and the amplitude of the internal potentialPEAre respectively:
Figure BDA0002948964550000181
wherein E0Is a steady-state quantity of the amplitude of the potential in the AC side of the MMC, theta0Is a steady-state quantity of phase of potential in the AC side of the MMC, Ug0Is a steady-state quantity of the amplitude of the grid voltage.
Fig. 6 shows the functional relationship K between reactive power and internal potential phaseQθAnd reactive power andfunctional relationship K between internal potential amplitudesQEAre respectively:
Figure BDA0002948964550000191
wherein E0Is a steady-state quantity of the amplitude of the potential in the AC side of the MMC, theta0Is a steady-state quantity of phase of potential in the AC side of the MMC, Ug0Is a steady-state quantity of the amplitude of the grid voltage.
In fig. 6, the left dashed box part represents the equipment motion equation model of the MMC circulator, and the right dashed box part represents the network equation model. The modeling method provided by the embodiment of the invention separates the equipment from the network and can be expanded to interaction analysis between multiple equipment and different equipment.
To analyze the internal potential phase branch dynamics more clearly, the phase branch in fig. 6 can be converted to the structure shown in fig. 7. FIG. 7 is a diagram of a dynamic analysis of potential phase within a time scale of MMC DC voltage.
Wherein the transfer function GEθThe expression of(s) is:
Figure BDA0002948964550000192
as can be seen from fig. 7, the internal potential phase dynamics is determined in two steps. Firstly, the dynamic phase will affect the change of the output active power, and thus change the unbalanced power. The change of the unbalanced output active power is divided into two parts, one part is the change delta P of the output active power directly influenced by the phase dynamicθThis branch is only subject to the network equation KPθThe influence of (1), i.e. only in relation to the external network to which the MMC converter is connected, for the case of an infinite grid as shown in fig. 5, only in relation to the grid strength and the steady state operating point; another part is the active power change Δ P which is dynamically influenced by the amplitudeEThis branch is left out of the network equation KPEIs also influenced by the amplitude and phase branch transfer function G of the MMC current converterEθ(s) influence of function GEθ(s) is the coupling between amplitude and phase introduced by the network equations as in fig. 6.
And the second step is that under the drive of unbalanced active power, the phase delta theta' is changed through the equivalent inertia and damping coefficient of the converter. It is noted that also a part of the phase dynamics Δ θ "is affected by the unbalanced reactive dynamics. Different from the amplitude branch circuit, the coupling of the amplitude branch circuit to the phase dynamics is introduced through an external network, and the branch circuit is the change of the phase delta theta' directly caused by the reactive power and represents the coupling relation between the reactive power of the equipment and the phase dynamics.
In a third application scenario, the mechanism of the internal potential amplitude dynamics is analyzed. Similarly, assuming that the MMC is connected to the infinite grid in fig. four, the amplitude branch in fig. 6 can be converted to the structure shown in fig. 8. FIG. 8 is a diagram of a dynamic analysis of the magnitude of a potential within the time scale of the MMC DC voltage.
As can be seen from fig. 8, the dynamics of the potential amplitude within the time scale of the MMC dc voltage also form a closed loop structure. The amplitude dynamics affect the change of the output reactive power, and the part of the influence is divided into delta Q directly affected by the amplitude dynamicsEAnd Δ Q indirectly influenced by phase dynamics coupling introduced via an external networkθ。ΔQEThe influence of which is partly determined by KPEOnly with external network information; delta QθThe partial influence is not only dependent on the external network but also influenced by the transfer function GEθ(s) influence of the reaction. In addition, under the drive of unbalanced reactive power, the change of the potential amplitude in the converter can be caused.
In a fourth application scenario, the equation of motion model of the MMC is used for system stability analysis. To clearly illustrate the influence of the controller parameters on the equivalent inertia coefficient and the damping coefficient of the MMC, an example is given when the converter operates at a rated active power of 0.7pu, at this time, the parameters of the dc voltage loop and the reactive power loop are both kept unchanged, which are (0.01, 0.5), (1e-6, 1e-4), respectively, the grid short circuit ratio SCR is 3.5, and other parameters are consistent with those in table 1.
Fixed kp3When k is 10, let ki3Varying from 500 to 5000, the phase-locked loop bandwidth varies from 5Hz to 30 Hz. Different ki3The MMC equivalent inertia/damping characteristic curve with frequency under the parameter is shown in figure 9a and figure 9 b. FIG. 9a is ki3The curve of the variation of the MMC DC voltage time scale inertia along with the frequency under the variation is shown in figure 9b as ki3And (3) the MMC direct voltage time scale damping is changed along with the frequency change curve. Wherein the curve 911, the curve 912, the curve 913, the curve 914, the curve 915 and the curve 916 are k respectivelyi3Inertia characteristic change curves with parameters of 500, 1000, 2000, 3000, 4000 and 5000. Wherein the curve 921, the curve 922, the curve 923, the curve 924, the curve 925 and the curve 926 are k respectivelyi3Damping characteristic change curves with parameters of 500, 1000, 2000, 3000, 4000, 5000.
It can be seen that hold kp3Invariably, with ki3And the equivalent inertia and the damping presented by the MMC are gradually increased. Wherein the equivalent inertia is subject to a parameter ki3Is less, the equivalent damping is affected slightly more, and both are affected less by the parameter as the frequency increases.
Fixed ki3Let k equal to 2000p3Varying from 50 to 200, the phase-locked loop bandwidth varies from 10Hz to 35 Hz. Different parameter kp3The curves of the lower MMC equivalent inertia/damping characteristics with frequency are shown in fig. 10a and 10 b. FIG. 10a is kp3The time scale inertia of the MMC direct voltage under the change is along with the change curve of the frequency, and the graph 10b is kp3And (3) the MMC direct-current voltage time scale damping is changed along with the frequency change curve. Wherein the curve 111, the curve 112, the curve 113, the curve 114, the curve 115 and the curve 116 are respectively kp3Inertia characteristic curves with parameters 50, 80, 100, 120, 150, 200. Wherein the curve 121, the curve 122, the curve 123, the curve 124, the curve 125 and the curve 126 are respectively kp3The variation curve of the damping characteristic when the parameters are 50, 80, 100, 120, 150 and 200.
It can be seen that hold ki3Invariably, with kp3The equivalent inertia damping embodied by the MMC is obviously increased after the equivalent inertia damping is gradually increased; equivalent inertia dependent parameter kp3Has very little influence when the frequency isAt 15Hz or below, with kp3Slightly reduced equivalent inertia, with a frequency above 15Hz, with kp3The equivalent inertia slightly increases.
As can be concluded from fig. 9 and 10, changing the control parameters of the phase locked loop mainly affects the damping embodied by the MMC converter, and the larger the controller parameter is, the larger the damping it embodies. Under the same set of parameters, with the increase of frequency, inertia and damping embodied by the MMC are both obviously reduced, namely the disturbance immunity of the system to high frequency under the same set of parameters is weaker. From the above analysis, it can be known that the equivalent damping of the MMC can be increased by optimizing the phase-locked loop parameters, thereby improving the stability of the system.
To verify the above conclusion, at 2.0s, a disturbance is added to the grid to make the phase step 5 °, comparing the dynamic response of the active power under different pll parameters, as shown in fig. 11, where fig. 11 is the dynamic response of the active power under different pll parameters. As can be seen by the long dashed line in the figure, when the pll parameter is (0.1, 500), the system is divergent; when holding ki3To 500, increase kp3，kp3When 10 is taken, the system converges, as shown by the solid line, i.e., the system is stable; in addition, when k is heldp3Is 0.1, increase ki3，ki3Taking 1000, the system converges, as indicated by the short dashed line, i.e. the system may also become stable. Therefore, the system can be stabilized from instability by increasing the parameters of the phase-locked loop controller within a certain range. From the inertia and damping characteristic analysis, the physical essence is that after the parameters of the phase-locked loop controller are increased, the inertia and damping provided by the MMC converter to the system are enhanced, so that the stability of the system is enhanced.
Fig. 12 is a schematic structural diagram of a modular multilevel converter modeling apparatus according to an embodiment of the present invention, and as shown in fig. 12, the modular multilevel converter modeling apparatus according to the embodiment includes:
and the voltage component determining module 121 is configured to determine a differential mode component and a common mode component of the sub-module capacitor voltage in the MMC time domain.
A coordinate transformation module 122 for transforming the differential mode component and the common mode component to a dq coordinate system.
The linearization processing module 123 is configured to perform linearization processing on the converted differential mode component and common mode component to obtain an MMC submodule capacitor voltage s-domain small signal model; obtaining an MMC unbalance active power linearization model according to the dynamic characteristics of the MMC sub-modules; and obtaining a linear model of the voltage of the MMC direct current side according to the dynamic characteristics of the MMC sub-modules.
The model establishing module 124 is used for obtaining a mathematical model of the MMC according to the MMC vector control strategy, and the mathematical model is dynamically established according to the voltage of the MMC sub-module; and establishing a motion equation model of the MMC according to the mathematical model of the MMC.
The modeling apparatus for a modular multilevel converter provided in this embodiment is used to implement the technical solution of the modeling method for a modular multilevel converter shown in fig. 1, and the implementation principle and the technical effect are similar, which are not described herein again.
The present invention also provides a storage medium containing computer executable instructions which when executed by a computer processor are for performing a method of modeling a modular multilevel converter, the method comprising:
determining a differential mode component and a common mode component of the capacitance voltage of the submodule in the MMC time domain; transforming the differential mode component and the common mode component to a dq coordinate system; carrying out linearization processing on the converted differential mode component and common mode component to obtain an MMC submodule capacitor voltage s-domain small signal model; obtaining an MMC unbalance active power linearization model according to the dynamic characteristics of the MMC sub-modules; obtaining a linear model of the voltage of the MMC direct current side according to the dynamic characteristics of the MMC sub-modules; obtaining a mathematical model of the MMC according to an MMC vector control strategy, wherein the mathematical model is dynamically established according to the voltage of a submodule of the MMC; and establishing a motion equation model of the MMC according to the mathematical model of the MMC.
It is to be noted that the foregoing is only illustrative of the preferred embodiments of the present invention and the technical principles employed. Those skilled in the art will appreciate that the present invention is not limited to the particular embodiments disclosed, but is capable of numerous rearrangements, modifications, and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, although the present invention has been described in more detail by the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the spirit of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims (10)

1. A modeling method for a modular multilevel converter is characterized by comprising the following steps:
determining a differential mode component and a common mode component of a sub-module capacitor voltage of a modular multilevel converter MMC in a time domain;
transforming the differential mode component and the common mode component to a dq coordinate system;
carrying out linearization processing on the converted differential mode component and common mode component to obtain a small signal model of the capacitance voltage s domain of the MMC sub-module;
obtaining an MMC unbalance active power linearization model according to the dynamic characteristics of the MMC sub-modules;
obtaining a linear model of the voltage of the MMC direct current side according to the dynamic characteristics of the MMC sub-modules;
obtaining a mathematical model of the MMC according to an MMC vector control strategy, wherein the mathematical model is dynamically established according to the voltage of a submodule of the MMC;
and establishing a motion equation model of the MMC according to the mathematical model of the MMC.
2. The method of claim 1, wherein determining the differential-mode component and the common-mode component of the sub-module capacitance voltage in the MMC time domain comprises:
according to the formula
Figure FDA0002948964540000011
Determining a differential mode component of the capacitance voltage of the submodule in the MMC time domain;
wherein C isarmEquivalent sub-module capacitance, C, for one bridge armarmC is the capacitance value of each submodule, N is the number of submodules of each bridge arm,
Figure FDA0002948964540000012
is the differential mode component of the bridge arm output voltage,
Figure FDA0002948964540000013
for the common-mode component of the bridge arm modulation function,
Figure FDA0002948964540000014
for the differential-mode component of the bridge arm modulation function,
Figure FDA0002948964540000015
is the common-mode component of the bridge arm currents,
Figure FDA0002948964540000016
is the differential-mode component of the bridge arm current,
Figure FDA0002948964540000017
is the internal potential of the inverter and,
Figure FDA0002948964540000018
ucjpfor the upper bridge arm to output voltage ucjnOutputting voltage for a lower bridge arm;
according to the formula
Figure FDA0002948964540000019
Determining a common-mode component of the capacitance voltage of the submodule in the MMC time domain;
wherein the content of the first and second substances,
Figure FDA0002948964540000021
is the common-mode component of the bridge arm output voltage,
Figure FDA0002948964540000022
ucjpfor the upper bridge arm to output voltage ucjnAnd outputting voltage for the lower bridge arm.
3. The method of claim 2, wherein transforming the differential mode component and the common mode component to a dq coordinate system comprises:
transforming the differential and common mode components to a dq coordinate system using a dq transformation matrix P as follows:
Figure FDA0002948964540000023
the sub-module capacitor voltage differential mode component after dq conversion is
Figure FDA0002948964540000024
Wherein:
Figure FDA0002948964540000025
is the d-axis component of the differential-mode component of the sub-module capacitance voltage,
Figure FDA0002948964540000026
q-axis component, omega, of the differential-mode component of the sub-module capacitor voltage1For the fundamental angular frequency of the ac system,
Figure FDA0002948964540000027
for the d-axis component of the bridge arm differential mode modulation current,
Figure FDA0002948964540000028
modulating a q-axis component of the current for the bridge arm differential mode;
Figure FDA0002948964540000029
the common mode component of the sub-module capacitor voltage after dq conversion is
Figure FDA00029489645400000210
Wherein:
Figure FDA00029489645400000211
is the d-axis component of the common mode component of the sub-module capacitor voltage,
Figure FDA00029489645400000212
being the q-axis component of the common mode component of the sub-module capacitor voltage,
Figure FDA00029489645400000213
is a direct current component in the common mode component of the sub-module capacitor voltage,
Figure FDA00029489645400000214
for the d-axis component of the bridge arm common mode modulation current,
Figure FDA00029489645400000215
for the q-axis component of the bridge arm common mode modulation current,
Figure FDA00029489645400000216
the DC component of the bridge arm common mode modulation current is obtained;
Figure FDA0002948964540000031
wherein the content of the first and second substances,
Figure FDA0002948964540000032
is the dc component of the MMC bridge arm common mode current,
Figure FDA0002948964540000033
for the d-axis component of the MMC bridge arm common mode current,
Figure FDA0002948964540000034
for the q-axis component of the MMC bridge arm common mode current,
Figure FDA0002948964540000035
is the d-axis component of the differential mode current of the MMC bridge arm,
Figure FDA0002948964540000036
for the q-axis component of the MMC bridge arm differential mode current,
Figure FDA0002948964540000037
for the dc component of the MMC bridge arm common mode modulation function,
Figure FDA0002948964540000038
for the MMC bridge arm common mode modulation function d-axis component,
Figure FDA0002948964540000039
for the q-axis component of the MMC bridge arm common mode modulation function,
Figure FDA00029489645400000310
is the d-axis component of the differential mode current of the MMC bridge arm,
Figure FDA00029489645400000311
q-axis component, omega, of differential mode current of bridge arm of MMC1Is the fundamental angular frequency of the ac system.
4. The method of claim 3, wherein the linearized s-domain small signal model of the differential-mode component of the sub-module capacitor voltage is:
Figure FDA00029489645400000312
the s-domain small signal model of the common-mode component of the sub-module capacitor voltage after linearization processing is as follows:
Figure FDA00029489645400000313
where s is the laplace operator.
5. The method of claim 4, wherein the obtaining the MMC imbalance active power linearization model according to the dynamic characteristics of the MMC sub-modules comprises:
using the formula
Figure FDA00029489645400000314
Obtaining the MMC unbalance active power linearization model, wherein, the delta PdcRepresenting the unbalanced power, Δ Pdc＝ΔPin-ΔP，PinRepresents the input power of the direct current side, and P represents the output power of the alternating current side;
transfer function G1(s), transfer function G2(s), transfer function G3(s) are respectively:
Figure FDA0002948964540000041
Figure FDA0002948964540000042
Figure FDA0002948964540000043
wherein the content of the first and second substances,
Figure FDA0002948964540000044
is the steady-state component of the d-axis component of the common-mode component of the sub-module capacitor voltage,
Figure FDA0002948964540000045
is the steady-state component of the q-axis component of the common-mode component of the sub-module capacitor voltage,
Figure FDA0002948964540000046
is a steady-state component of the dc component in the common-mode component of the sub-module capacitor voltages,
Figure FDA0002948964540000047
is the steady-state component of the d-axis component of the differential-mode component of the sub-module capacitance voltage,
Figure FDA0002948964540000048
is the steady-state component of the q-axis component of the differential-mode component of the sub-module capacitor voltage,
Figure FDA0002948964540000049
is the steady-state component of the dc component of the MMC bridge arm common mode modulation function,
Figure FDA00029489645400000410
is a steady-state component of the MMC bridge arm common-mode modulation function d-axis component,
Figure FDA00029489645400000411
is the steady-state component of the q-axis component of the MMC bridge arm common-mode modulation function,
Figure FDA00029489645400000412
is a steady-state component of the d-axis component of the differential-mode current of the MMC bridge arm,
Figure FDA00029489645400000413
the component is a steady-state component of a q-axis component of the MMC bridge arm differential mode current.
6. The method of claim 5, wherein said obtaining a linearized model of the DC side voltage of the MMC sub-module based on the dynamics of the MMC sub-module comprises:
using the formula
Figure FDA00029489645400000414
Obtaining a linear model of the voltage of the MMC direct current side, wherein the transfer function Z1(s), transfer function Z2(s), transfer function Z3(s) are respectively:
Figure FDA0002948964540000051
Figure FDA0002948964540000052
Figure FDA0002948964540000053
wherein, Udc0Is a steady-state component of the dc side voltage,
Figure FDA0002948964540000054
is the steady-state component of the bridge arm common mode current direct current component.
7. The method according to any one of claims 1 to 6, wherein the establishing a motion equation model of the MMC according to the mathematical model of the MMC comprises:
solving an equivalent inertia coefficient and a damping coefficient in an MMC motion equation according to the mathematical model of the MMC;
and establishing a motion equation model of the MMC according to the equivalent inertia coefficient and the damping coefficient in the motion equation of the MMC.
8. The method of claim 7, wherein solving the equivalent inertia and damping coefficients in the MMC equation of motion according to the mathematical model of the MMC comprises:
solving an equivalent inertia coefficient M(s) and a damping coefficient D(s) of the MMC according to the following formula:
Figure FDA0002948964540000055
wherein
Figure FDA0002948964540000056
9. A modular multilevel converter modeling apparatus, comprising:
the voltage component determining module is used for determining a differential mode component and a common mode component of the capacitance voltage of the submodule in the time domain of the modular multilevel converter MMC;
a coordinate transformation module for transforming the differential mode component and the common mode component to a dq coordinate system;
the linearization processing module is used for carrying out linearization processing on the converted differential mode component and the converted common mode component to obtain a small signal model of the capacitance voltage s domain of the MMC sub-module; obtaining an MMC unbalance active power linearization model according to the dynamic characteristics of the MMC sub-modules; obtaining a linear model of the voltage of the MMC direct current side according to the dynamic characteristics of the MMC sub-modules;
the model establishing module is used for obtaining a mathematical model of the MMC according to an MMC vector control strategy, and the mathematical model is dynamically established according to the voltage of the MMC sub-module; and establishing a motion equation model of the MMC according to the mathematical model of the MMC.
10. A computer-readable storage medium, on which a computer program is stored, which, when being executed by a processor, implements a modular multilevel converter modeling method according to any of claims 1 to 8.
CN202110203709.1A 2021-02-23 2021-02-23 Modeling method and device for modular multilevel converter and storage medium Pending CN113158416A (en)

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CN111262465A (en) * 2020-01-22 2020-06-09 上海电力大学 Passive control method for modular multilevel matrix converter
CN112350600A (en) * 2020-10-22 2021-02-09 华南理工大学 Modular multilevel converter power decoupling control method based on disturbance estimation

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Application publication date: 20210723