CN113765345A - Method for suppressing capacitor voltage fluctuation of modular multilevel converter - Google Patents
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/12—Arrangements for reducing harmonics from ac input or output
- H02M1/126—Arrangements for reducing harmonics from ac input or output using passive filters
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
- H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
- H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M7/483—Converters with outputs that each can have more than two voltages levels
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
- H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
- H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M7/53—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M7/537—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
- H02M7/5387—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration
- H02M7/53871—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration with automatic control of output voltage or current
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- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
- H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
- H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M7/53—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M7/537—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
- H02M7/539—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters with automatic control of output wave form or frequency
- H02M7/5395—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters with automatic control of output wave form or frequency by pulse-width modulation
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Abstract
The invention relates to a method for inhibiting the voltage fluctuation of a capacitor of a modular multilevel converter, which comprises the following steps: establishing an MMC fluctuation capacitor voltage state equation based on a PCHD model; based on the established MMC fluctuation capacitor voltage state equation, an MMC capacitor voltage fluctuation passive consistency controller based on a PCHD model is further established to obtain fluctuation capacitor voltage control quantity; processing the voltage control quantity of the fluctuation capacitor by adopting a pulse modulation method to obtain a corresponding trigger pulse signal; and controlling the switching state of the converter of each phase bridge arm submodule of the MMC according to the trigger pulse signal. Compared with the prior art, the passive consistency control method based on the PCHD model is used for suppressing the voltage fluctuation of the MMC capacitor, has the advantages of simple control law form, small mean deviation and good stability, and can effectively suppress the voltage fluctuation of the MMC capacitor.
Description
Technical Field
The invention relates to the technical field of control of modular multilevel converters, in particular to a method for suppressing capacitor voltage fluctuation of a modular multilevel converter.
Background
The Modular Multilevel Converter (MMC) is formed by cascading a plurality of Sub-modules (SM) with the same structure, wherein the Sub-modules can be divided into a half H-bridge type, a full H-bridge type and a double-clamping type Sub-module type. The MMC has the advantages of low harmonic content, low switching loss, strong fault ride-through capability, convenience for modular capacity expansion, convenience for industrial production and the like, and is widely applied to the field of large-scale renewable energy grid connection at present. But because extensive renewable energy power generation has intermittent type nature, undulant characteristics, leads to three-phase MMC interphase energy unbalance easily, and then causes sub-module capacitor voltage unbalance, and MMC capacitor voltage undulant must increase the transverter loss, leads to exchanging the side output voltage and deviates, can influence the reliable operation of system when serious.
Therefore, it is necessary to suppress the fluctuation of the MMC capacitor voltage, the conventional method adopts a vector control method, the controller is designed according to the nonlinear nature of the MMC submodule capacitor voltage fluctuation system, and the immunity and robustness of the vector controller face the challenge which is difficult to overcome when an uncertain disturbance condition exists because the energy is not considered; compared with the traditional vector control method, the nonlinear control method is adopted in the prior art, and the controller capable of reflecting the nonlinear nature of the MMC sub-module capacitor voltage fluctuation system is designed from the energy perspective, so that the control performance is improved in the aspects of stability and robustness of a closed-loop control system. Therefore, how to realize the improvement of dynamic and static response performance on the premise that the design of the controller is as simple as possible and ensure the further improvement of the global progressive stability and robustness of the system is a key problem which must be solved by the engineering application of the MMC submodule capacitor voltage fluctuation inhibition.
Disclosure of Invention
The invention aims to overcome the defects in the prior art and provide a method for inhibiting the voltage fluctuation of a capacitor of a modular multilevel converter, and the passive consistency controller is designed to realize a simple-form controller, so that the voltage fluctuation of the capacitor of an MMC can be effectively inhibited, and the overall gradual stability and robustness of a system can be improved.
The purpose of the invention can be realized by the following technical scheme: a modular multilevel converter capacitor voltage fluctuation suppression method comprises the following steps:
s1, establishing an MMC fluctuation capacitance voltage state equation based on a PCHD (port-controlled Hamiltonian with dispersion, port controlled dissipation Hamiltonian) model;
s2, further constructing an MMC capacitor voltage fluctuation passive consistency controller based on the PCHD model based on the MMC fluctuation capacitor voltage state equation established in the step S1 to obtain fluctuation capacitor voltage control quantity;
s3, processing the voltage control quantity of the fluctuation capacitor by adopting a pulse modulation method to obtain a corresponding trigger pulse signal;
and S4, controlling the switching state of the converter of each phase bridge arm submodule of the MMC according to the trigger pulse signal.
Further, the step S1 specifically includes the following steps:
s11, respectively defining a state variable, an input variable and an output variable under a dq rotating coordinate system, wherein the state variable is a product of a three-phase injection circulation frequency doubling dq axis component and a bridge arm inductance, the input variable is a three-phase fluctuation capacitance voltage dq axis component, and the output variable is a three-phase injection circulation frequency doubling dq axis component;
and S12, establishing an MMC fluctuation capacitance voltage state equation based on the PCHD model based on the defined state variable, the defined input variable and the defined output variable.
Further, the MMC fluctuation capacitance voltage state equation is specifically:
x＝[x1 x2]T＝[Lmicird Lmicirq]T
u＝[u1 u2]T＝[ucird ucirq]T
y＝[y1 y2]T＝[icird icirq]T
where x is a state variable, u is an input variable, y is an output variable, LmIs bridge arm inductance icird、icirqThe components u of the d-axis and q-axis of the three-phase injected circulating current frequency doubling are respectivelycird、ucirqD-axis and q-axis components of the three-phase ripple capacitance voltage, J (x) is an interconnection matrix, R (x) is a damping matrix, g (x) is a port matrix, H (x) is an energy function, omega0At fundamental angular frequency, RmIs a resistance of a bridge arm, and is,
is a differential operator.
Further, the step S2 specifically includes the following steps:
s21, introducing a consistency control law on the basis of the PCHD model, and setting an expected balance point of the MMC sub-module fluctuation capacitor voltage system after circulation current injection;
and S22, obtaining a passive consistency control law based on a PCHD model by taking the difference between the state variable and the expected balance point and the differential value thereof as a control target and combining an MMC fluctuation capacitor voltage state equation, thus obtaining the fluctuation capacitor voltage control quantity.
Further, the consistency control law introduced in step S21 specifically includes:
α＝1
wherein x iseFor state variable error, x is the set desired balance point,
and
the reference tracks are respectively three-phase injection circulation frequency doubling d-axis and q-axis component reference tracks, and alpha is an error coefficient.
Further, the step S22 specifically includes the following steps:
s221, designing a corresponding expected energy function by taking the difference between the state variable and the expected balance point and the differential value thereof as a control target, wherein the difference and the differential value are zero;
s222, obtaining a state equation of the MMC sub-module fluctuation capacitor voltage closed-loop system by combining an MMC fluctuation capacitor voltage state equation based on a designed expected energy function;
and S223, further obtaining a PCHD model-based passive consistency control law according to a state equation of the MMC sub-module fluctuation capacitance voltage closed-loop system.
Further, the control target in step S221 is specifically:
the designed expected energy function is specifically:
wherein Hd(x) D is the bridge arm inductance matrix for the desired energy function.
Further, the state equation of the MMC sub-module fluctuation capacitance-voltage closed-loop system in step S222 specifically is:
wherein, Jd(x) Interconnection matrix desired for the system, Rd(x) A desired damping matrix for the system.
Further, the interconnection matrix desired by the system is specifically:
Jd(x)＝J(x)+Ja(x)
Ja(x)＝0
wherein, Ja(x) Is an injected dissipation matrix;
the desired damping matrix of the system is specifically:
Rd(x)＝R(x)+Ra(x)
wherein R isa(x) For an injected damping matrix, ra1、ra2Is the injected positive damping parameter.
Further, the passive consistency control law based on the PCHD model in step S223 specifically includes:
A1＝8ω0Lm-5(Rm+ra1)
A2＝10ω0Lm+4(Rm+ra2)
B1＝-10ω0Lm+4(Rm+ra1)
B2＝-8ω0Lm-5(Rm+ra2)
C1＝2ω0Lm
C2＝-2ω0Lm
D1＝D2＝Rm
wherein A is1、B1、C1、D1Are all d-axis control variables, A2、B2、C2、D2Are all q-axis control variables, ucird、ucirqThe three-phase fluctuation capacitance voltage d-axis and q-axis components are respectively the fluctuation capacitance voltage control quantity.
Compared with the prior art, the method is based on a PCHD model and passivity and consistency theories, based on the established MMC fluctuation capacitor voltage state equation, and through energy function shaping, the control target can obtain the minimum value at an expected balance point, and the global gradual stability of the system can be effectively ensured, so that the accuracy of obtaining the subsequent fluctuation capacitor voltage control quantity is ensured, and the reliability of MMC capacitor voltage fluctuation inhibition is improved;
in addition, the PCHD model-based MMC capacitor voltage fluctuation passive consistency controller can realize the rapid tracking and the synchronous tracking of the injected circulation reference track while ensuring the overall stability of the system, has a simple control law form, and has better transient performance and stability.
Drawings
FIG. 1 is a schematic flow diagram of the process of the present invention;
FIG. 2 is a schematic diagram of an embodiment of an application process;
FIG. 3 is a schematic diagram of an MMC three-phase equivalent circuit structure;
FIG. 4 is a schematic diagram of the fluctuation of the capacitance and voltage of the MMC sub-module after the method of the present invention is applied in the embodiment.
Detailed Description
The invention is described in detail below with reference to the figures and specific embodiments.
Examples
As shown in fig. 1, a modular multilevel capacitor voltage fluctuation suppression method includes the following steps:
s1, establishing an MMC fluctuation capacitance-voltage state equation based on a PCHD model, specifically defining a state variable, an input variable and an output variable respectively under a dq rotation coordinate system: the state variable is the product of the three-phase injection circulation double frequency dq axis component and the bridge arm inductance, the input variable is the three-phase fluctuation capacitance voltage dq axis component, and the output variable is the three-phase injection circulation double frequency dq axis component;
establishing and obtaining an MMC fluctuation capacitor voltage state equation based on the defined state variable, the defined input variable and the defined output variable:
x＝[x1 x2]T＝[Lmicird Lmicirq]T
u＝[u1 u2]T＝[ucird ucirq]T
y＝[y1 y2]T＝[icird icirq]T
where x is a state variable, u is an input variable, y is an output variable, LmIs bridge arm inductance icird、icirqThe components u of the d-axis and q-axis of the three-phase injected circulating current frequency doubling are respectivelycird、ucirqD-axis and q-axis components of the three-phase ripple capacitance voltage, J (x) is an interconnection matrix, R (x) is a damping matrix, g (x) is a port matrix, H (x) is an energy function, omega0At fundamental angular frequency, RmIs a resistance of a bridge arm, and is,
is a differential operator;
s2, further constructing an MMC capacitor voltage fluctuation passive consistency controller based on the PCHD model based on the MMC fluctuation capacitor voltage state equation established in the step S1 to obtain a fluctuation capacitor voltage control quantity, specifically:
firstly, introducing a consistency control law, and setting an expected balance point after the MMC sub-module fluctuation capacitance voltage system injects circulating current:
wherein x is*In order to expect a point of equilibrium,
and
respectively injecting circulating current double frequency d-axis and q-axis component reference tracks for three phases;
the consistency control law is as follows:
wherein x iseIn order to be a state variable error,
x1＝Lmicird,x2＝Lmicirq,
the expected voltage tracks of the MMC three-phase capacitors are consistent, so that the error coefficient alpha is 1;
then the difference between the state variable and the expected balance point and the differential value differential are zero as the control target (namely x-x)*0 and
) Designing a corresponding expected energy function:
wherein Hd(x) D is bridge arm inductance matrix with L elements on diagonal lines as function of expected energymAnd the other elements are all 0;
and then based on the designed expected energy function, combining an MMC fluctuation capacitor voltage state equation to obtain the state equation of the MMC submodule fluctuation capacitor voltage closed-loop system:
Jd(x)＝J(x)+Ja(x)
Ja(x)＝0
Rd(x)＝R(x)+Ra(x)
wherein, Jd(x) Interconnection matrix desired for the system, Rd(x) Damping matrix desired for the system, Ja(x) For an implanted dissipative matrix, Ra(x) For an injected damping matrix, ra1、ra2Is the injected positive damping parameter;
and finally, further obtaining a passive consistency control law based on a PCHD model according to a state equation of the MMC sub-module fluctuation capacitance voltage closed-loop system:
wherein A is1＝8ω0Lm-5(Rm+ra1)；A2＝10ω0Lm+4(Rm+ra2)；
B1＝-10ω0Lm+4(Rm+ra1)；B2＝-8ω0Lm-5(Rm+ra2)；
C1＝2ω0Lm；C2＝-2ω0Lm；
D1＝D2＝Rm；
A1、B1、C1、D1Are all d-axis control variables, A2、B2、C2、D2Are all q-axis control variables, ucird、ucirqThe three-phase fluctuation capacitance voltage d-axis and q-axis components are respectively used as the fluctuation capacitance voltage control quantity;
s3, processing the voltage control quantity of the fluctuation capacitor by adopting a pulse modulation method to obtain a corresponding trigger pulse signal;
and S4, controlling the switching state of the converter of each phase bridge arm submodule of the MMC according to the trigger pulse signal.
The present embodiment applies the above method, and the process thereof is shown in fig. 2:
step 1: the three-phase MMC circuit structure and the topological diagram of the sub-modules are shown in FIG. 3, and the MMC fluctuation capacitor voltage dynamic equation under dq rotation coordinate system obtained from FIG. 3 is
Wherein, ω is0At the fundamental angular frequency, LmIs bridge arm inductance, RmIs bridge arm resistance icirdAnd icirqD-and q-axis components, u, for frequency doubling of the three-phase injected circulating currentcirdAnd ucirqThe d-axis and q-axis components of the three-phase ripple capacitance voltage,
t is time, which is a differential operator.
Selecting a state variable x, an input variable u and an output variable y as follows:
in the formula: [. the]TIs the transpose of the matrix.
The orthodefinite quadratic energy function h (x) is designed as:
carrying out equivalent transformation on the MMC fluctuation capacitance voltage dynamic equation (1) to obtain the PCHD model of the MMC submodule capacitor voltage fluctuation:
wherein the content of the first and second substances,
interconnection matrix
Damping matrix
Port matrix
In the formula (I), the compound is shown in the specification,
is a differential operator.
The dissipation inequality can be derived from equations (3) and (4):
the left side of the equation (5) is increment of the whole MMC fluctuation capacitor voltage system, the right side is external supply energy, and the passivity theory shows that: mapping u → x is strictly passive in output, and the MMC fluctuation capacitor voltage system has passive characteristics.
Step 2: according to the system control performance target, setting the expected balance point of the MMC submodule capacitor voltage fluctuation system after injection circulation to be
In the formula (I), the compound is shown in the specification,
and
and d-axis and q-axis component reference tracks are frequency-doubled for the three-phase injected circulating current.
According to control target x-x*0 and
expected energy function of MMC submodule capacitor voltage fluctuation suppression control system
From the formulas (4) and (7), the state equation of the MMC submodule fluctuation capacitance voltage closed-loop system can be obtained as
In the formula, Jd(x)＝J(x)+Ja(x) Interconnection matrix desired for the system, Rd(x)＝R(x)+Ra(x) Damping matrix desired for the system, Ja(x)＝0、
Respectively implanted dissipation matrix and resistanceDamping matrix ra1、ra2Is the injected positive damping parameter.
The PCHD model-based passive consistency control law obtained from equation (8) is
The formula (9) can ensure that the closed-loop control system can realize effective inhibition of the capacitance voltage fluctuation of the MMC sub-module on the premise of global gradual stabilization.
In this embodiment, a simulation model of an MMC capacitor voltage fluctuation control system is built in MATLAB/Simulink to verify the effectiveness of the present invention, and simulation parameters of this embodiment are shown in table 1.
TABLE 1
And carrying out simulation test by adopting an MMC capacitor voltage fluctuation suppression method based on a PCHD model under the steady-state operation of the MMC system. The simulation result of the method for suppressing the capacitance-voltage fluctuation of the promoter module when t is 0.3s is shown in fig. 4. Fig. 4 shows that when sub-module capacitance voltage fluctuation suppression is not adopted before t is 0.3s, MMC sub-module capacitance voltage fluctuation is large, after the PCHD model-based passive consistency control method is implemented for t is 0.3s, the transient transition time period is fast in dynamic response, effective suppression of MMC sub-module capacitance voltage fluctuation is achieved, three-phase capacitance voltage mean deviation is small after stabilization, and system stability is improved.
Claims (10)
1. A method for suppressing the voltage fluctuation of a capacitor of a modular multilevel converter is characterized by comprising the following steps:
s1, establishing an MMC fluctuation capacitor voltage state equation based on a PCHD model;
s2, further constructing an MMC capacitor voltage fluctuation passive consistency controller based on the PCHD model based on the MMC fluctuation capacitor voltage state equation established in the step S1 to obtain fluctuation capacitor voltage control quantity;
s3, processing the voltage control quantity of the fluctuation capacitor by adopting a pulse modulation method to obtain a corresponding trigger pulse signal;
and S4, controlling the switching state of the converter of each phase bridge arm submodule of the MMC according to the trigger pulse signal.
2. The method for suppressing the capacitor voltage fluctuation of the modular multilevel converter according to claim 1, wherein the step S1 specifically comprises the following steps:
s11, respectively defining a state variable, an input variable and an output variable under a dq rotating coordinate system, wherein the state variable is a product of a three-phase injection circulation frequency doubling dq axis component and a bridge arm inductance, the input variable is a three-phase fluctuation capacitance voltage dq axis component, and the output variable is a three-phase injection circulation frequency doubling dq axis component;
and S12, establishing an MMC fluctuation capacitance voltage state equation based on the PCHD model based on the defined state variable, the defined input variable and the defined output variable.
3. The method for suppressing the capacitor voltage fluctuation of the modular multilevel converter according to claim 2, wherein the MMC fluctuation capacitor voltage state equation is specifically as follows:
x＝[x1 x2]T＝[Lmicird Lmicirq]T
u＝[u1 u2]T＝[ucird ucirq]T
y＝[y1 y2]T＝[icird icirq]T
where x is a state variable, u is an input variable, y is an output variable, LmIs bridge arm inductance icird、icirqThe components u of the d-axis and q-axis of the three-phase injected circulating current frequency doubling are respectivelycird、ucirqD-axis and q-axis components of the three-phase ripple capacitance voltage, J (x) is an interconnection matrix, R (x) is a damping matrix, g (x) is a port matrix, H (x) is an energy function, omega0At fundamental angular frequency, RmIs a resistance of a bridge arm, and is,
is a differential operator.
4. The method for suppressing the capacitor voltage fluctuation of the modular multilevel converter according to claim 3, wherein the step S2 specifically comprises the following steps:
s21, introducing a consistency control law on the basis of the PCHD model, and setting an expected balance point of the MMC sub-module fluctuation capacitor voltage system after circulation current injection;
and S22, obtaining a passive consistency control law based on a PCHD model by taking the difference between the state variable and the expected balance point and the differential value thereof as a control target and combining an MMC fluctuation capacitor voltage state equation, thus obtaining the fluctuation capacitor voltage control quantity.
5. The method for suppressing the capacitor voltage fluctuation of the modular multilevel converter according to claim 4, wherein the consistency control law introduced in the step S21 is specifically as follows:
α＝1
wherein x iseFor state variable error, x is the set desired balance point,
and
the reference tracks are respectively three-phase injection circulation frequency doubling d-axis and q-axis component reference tracks, and alpha is an error coefficient.
6. The method for suppressing the capacitor voltage fluctuation of the modular multilevel converter according to claim 5, wherein the step S22 specifically comprises the following steps:
s221, designing a corresponding expected energy function by taking the difference between the state variable and the expected balance point and the differential value thereof as a control target, wherein the difference and the differential value are zero;
s222, obtaining a state equation of the MMC sub-module fluctuation capacitor voltage closed-loop system by combining an MMC fluctuation capacitor voltage state equation based on a designed expected energy function;
and S223, further obtaining a PCHD model-based passive consistency control law according to a state equation of the MMC sub-module fluctuation capacitance voltage closed-loop system.
7. The method according to claim 6, wherein the control targets in step S221 are specifically:
the designed expected energy function is specifically:
wherein Hd(x) D is the bridge arm inductance matrix for the desired energy function.
8. The method according to claim 7, wherein the state equation of the MMC sub-module fluctuation capacitor voltage closed-loop system in the step S222 is specifically as follows:
wherein, Jd(x) Interconnection matrix desired for the system, Rd(x) A desired damping matrix for the system.
9. The method for suppressing the capacitor voltage fluctuation of the modular multilevel converter according to claim 8, wherein the interconnection matrix desired by the system is specifically:
Jd(x)＝J(x)+Ja(x)
Ja(x)＝0
wherein, Ja(x) Is an injected dissipation matrix;
the desired damping matrix of the system is specifically:
Rd(x)＝R(x)+Ra(x)
wherein R isa(x) For an injected damping matrix, ra1、ra2Is the injected positive damping parameter.
10. The method according to claim 9, wherein the passive consistency control law based on the PCHD model in step S223 specifically includes:
A1＝8ω0Lm-5(Rm+ra1)
A2＝10ω0Lm+4(Rm+ra2)
B1＝-10ω0Lm+4(Rm+ra1)
B2＝-8ω0Lm-5(Rm+ra2)
C1＝2ω0Lm
C2＝-2ω0Lm
D1＝D2＝Rm
wherein A is1、B1、C1、D1Are all d-axis control variables, A2、B2、C2、D2Are all q-axis control variables, ucird、ucirqThe three-phase fluctuation capacitance voltage d-axis and q-axis components are respectively the fluctuation capacitance voltage control quantity.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202110967810.4A CN113765345B (en) | 2021-08-23 | Method for suppressing capacitor voltage fluctuation of modularized multi-level converter |
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| CN202110967810.4A CN113765345B (en) | 2021-08-23 | Method for suppressing capacitor voltage fluctuation of modularized multi-level converter |
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