CN113346781B - Passive consistency control method for grid-connected current of modular multilevel converter - Google Patents
Passive consistency control method for grid-connected current of modular multilevel converter Download PDFInfo
- Publication number
- CN113346781B CN113346781B CN202110734879.2A CN202110734879A CN113346781B CN 113346781 B CN113346781 B CN 113346781B CN 202110734879 A CN202110734879 A CN 202110734879A CN 113346781 B CN113346781 B CN 113346781B
- Authority
- CN
- China
- Prior art keywords
- grid
- mmc
- passive
- consistency
- matrix
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
- 238000000034 method Methods 0.000 title claims abstract description 41
- 238000012545 processing Methods 0.000 claims abstract description 4
- 239000011159 matrix material Substances 0.000 claims description 47
- 238000013016 damping Methods 0.000 claims description 14
- 230000003993 interaction Effects 0.000 claims description 3
- 230000001360 synchronised effect Effects 0.000 abstract description 8
- 230000000694 effects Effects 0.000 abstract description 2
- 238000010586 diagram Methods 0.000 description 8
- 238000004088 simulation Methods 0.000 description 5
- 239000003990 capacitor Substances 0.000 description 2
- 238000013461 design Methods 0.000 description 2
- 238000013507 mapping Methods 0.000 description 2
- 230000000750 progressive effect Effects 0.000 description 2
- 102000002274 Matrix Metalloproteinases Human genes 0.000 description 1
- 108010000684 Matrix Metalloproteinases Proteins 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 230000009977 dual effect Effects 0.000 description 1
- 230000005764 inhibitory process Effects 0.000 description 1
- 230000010355 oscillation Effects 0.000 description 1
- 238000007493 shaping process Methods 0.000 description 1
- 230000006641 stabilisation Effects 0.000 description 1
- 238000011105 stabilization Methods 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
- 230000001052 transient effect Effects 0.000 description 1
Images
Classifications
-
- 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
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
- H02J3/40—Synchronising a generator for connection to a network or to another generator
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- 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
-
- 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
- H02M7/539—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
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J2300/00—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
- H02J2300/20—The dispersed energy generation being of renewable origin
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Inverter Devices (AREA)
Abstract
The invention relates to a passive consistency control method for modular multilevel grid-connected current, which comprises the following steps: establishing MMC grid-connected current under the condition of unbalanced power grid voltage, and designing an expected global energy function of an MMC grid-connected system to obtain a PCHD model of the MMC grid-connected system under the condition of unbalanced power grid voltage; based on a PCHD model of an MMC grid-connected system, a consistency method is combined to construct an MMC grid-connected passive consistency controller based on the PCHD model under the condition of unbalanced power grid voltage so as to obtain a control quantity; processing the control quantity by adopting a pulse modulation method to obtain a corresponding trigger pulse signal; and controlling the switching state of the converter of each phase of bridge arm submodule of the MMC according to the trigger pulse signal. Compared with the prior art, the method disclosed by the invention is combined with the PCHD model and the consistency method to realize independent synchronous control of the MMC grid-connected positive and negative sequence subsystems, has the advantages of simple control law form, no singular point and good stability, and can effectively improve the synchronous tracking effect of the grid-connected current.
Description
Technical Field
The invention relates to the technical field of control of modular multilevel converters, in particular to a passive consistency control method for grid-connected current of a modular multilevel converter.
Background
The Modular Multilevel Converter (MMC) is a Multilevel Converter capable of realizing high-voltage and medium-voltage power conversion without a transformer, and the MMC is widely applied to the field of large-scale renewable energy grid connection at present, however, when a single-phase short circuit occurs in a power grid, because a system alternating current can generate a negative sequence component, power oscillation is caused, stable operation of an MMC grid-connected system is finally influenced, and system instability can be caused in a severe case.
Therefore, the MMC grid-connected current needs to be controlled to achieve MMC grid-connected current balance, a vector control method is mostly adopted for control in the prior art, the method is designed for the nonlinear essence of an MMC grid-connected current system, and the energy is not used, so that when the uncertain disturbance condition exists, the disturbance resistance and robustness of a vector controller face challenges; compared with the traditional vector control method, the prior art is based on a nonlinear control method, and aims to design a controller capable of reflecting the nonlinear nature of an MMC grid-connected current system from the energy perspective, the method can improve the control performance in the aspects of stability and robustness of a closed-loop control system to a certain extent, but is complex in calculation, and cannot solve the problem that the correlation in a positive-sequence current subsystem and a negative-sequence current subsystem influences the passive control dynamic tracking performance, so that the control synchronism of the positive-sequence independent subsystem and the negative-sequence independent subsystem cannot be ensured, and the synchronous stable tracking of the positive-sequence system and the negative-sequence system cannot be reliably realized.
Disclosure of Invention
The invention aims to overcome the defects in the prior art and provide a modularized multi-level grid-connected current passive consistency control method to ensure the synchronous stable tracking of a positive sequence double system and a negative sequence double system.
The purpose of the invention can be realized by the following technical scheme: a modularized multi-level grid-connected current passive consistency control method comprises the following steps:
s1, establishing MMC grid-connected current under the condition of unbalanced grid voltage, and designing an expected global energy function of an MMC grid-connected system to obtain a PCHD (Port controlled Hamilton with dispersion) model of the MMC grid-connected system under the condition of unbalanced grid voltage;
s2, constructing a PCHD model-based MMC grid-connected system PCHD model based on the established PCHD model in the step S1, and combining a consistency method to obtain a controlled variable;
s3, processing the control quantity by adopting a pulse modulation method to obtain a corresponding trigger pulse signal;
and S4, controlling the switching states of the converters of the bridge arm sub-modules of each phase of the MMC according to the trigger pulse signals.
Further, the step S1 specifically includes the following steps:
s11, defining the state variable asDefining input variables as Defining an output variable asWherein the positive sequence subsystem state variable is Negative sequence subsystem state variables of
The positive sequence subsystem output variable isThe negative sequence subsystem output variable is
Wherein L is eq Is the inductance of the bridge arm,respectively the dq axis positive and negative sequence components of the output voltage at the AC side,are the dq axis positive and negative sequence components of the ac side supply current, the dq axis positive and negative sequence components of the AC side power supply voltage are respectively;
and S12, establishing an MMC grid-connected current state equation based on the PCHD model based on the state variable, the input variable and the output variable in the step S11, designing an expected global energy function of the MMC grid-connected system, and obtaining the PCHD model of the MMC grid-connected system under the condition of unbalanced power grid voltage.
Further, the MMC grid-connected current state equation specifically includes:
wherein J (x) is an interconnection matrix, R (x) is a damping matrix, g (x) is a port matrix, H (x) is an energy function, omega is fundamental angular frequency, R is bridge arm resistance,is a differential operator.
Further, the desired global energy function is specifically:
wherein x is * Is the desired trajectory for x and is,respectively are the expected positive and negative sequence components of the dq axis of the alternating-current side power supply current, and D is a bridge arm inductance matrix.
Further, the PCHD model of the MMC grid-connected system under the unbalanced power grid voltage specifically comprises:
wherein, J d (x) Expect the interconnection matrix, R, for the system d (x) Desired damping matrix for the system, J a (x)、R a (x) Respectively an injected dissipation matrix and a damping matrix.
Further, the step S2 specifically includes the following steps:
s21, setting Laplace matrix L of a positive sequence subsystem and a negative sequence subsystem of the MMC grid-connected system by combining a consistency method 1 、L 2 ;
S22, taking the difference between the state variable and the expected balance point as a control target, substituting the grid-connected current state variable error into a PCHD model-based passive consistency control expected energy function, and combining with the PCHD model of the MMC grid-connected system to obtain a closed loop state equation of the MMC grid-connected system;
and S23, combining an MMC grid-connected system closed loop state equation and an MMC grid-connected current state equation to obtain a passive consistency control law based on the PCHD model, namely obtaining the controlled variable.
Further, laplace matrix L of positive sequence subsystem and negative sequence subsystem of MMC grid-connected system 1 、L 2 The method comprises the following specific steps:
wherein, delta is L 1 、L 2 A is an adjacency matrix.
Further, the grid-connected current state variable error specifically includes:
wherein, A ij Is an interaction coefficient, α is an error coefficient, α =1 when the subsystems have the same desired trajectory; when the subsystem expects different trajectories, α =0.
Further, the PCHD model-based passive consistency control expected energy function is specifically:
further, the closed loop state equation of the MMC grid-connected system specifically includes:
further, the passive consistency control law based on the PCHD model specifically includes:
wherein,the dq axis positive and negative sequence components of the AC side power supply voltage are respectively the obtained control quantity r a11 、r a12 、r a21 、r a22 In order to have no controller coefficients,A 1 、A 2 、B 1 、B 2 、C 1 、C 2 、D 1 、D 2 positive sequence and negative sequence control variables, respectively.
Compared with the prior art, based on PCHD characteristics and passivity theory, the synchronization tracking of the grid-connected positive and negative sequence currents can be realized by introducing a consistency method, so that the synchronization effect is ensured; based on the established PCHD model of the MMC grid-connected system, the minimum value of a control target can be obtained at an expected balance point through energy function shaping, and the overall gradual stability of the system can be effectively ensured by utilizing the input and output mapping of the PCHD system, so that the accuracy of obtaining the subsequent control quantity is ensured, and the synchronous stable tracking of the MMC grid-connected positive and negative sequence dual system is reliably realized;
in addition, the PCHD model-based MMC grid-connected system passive consistency controller can realize synchronous tracking of grid-connected current while ensuring the overall stability of the system, and has the advantages of simple control law form, small calculated amount, and 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 a process for applying the method of the present invention;
FIG. 3 is a schematic diagram of a three-phase MMC circuit structure and its sub-module topology;
FIG. 4a is a schematic diagram of a positive sequence d-axis current waveform of the MMC in the embodiment;
FIG. 4b is a schematic diagram of a positive sequence q-axis current waveform of the MMC in the embodiment;
FIG. 4c is a schematic diagram of the negative sequence d-axis current waveform of the MMC in the embodiment;
FIG. 4d is a schematic diagram of the negative-sequence q-axis current waveform of the MMC 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 passive consistency control method for a modular multilevel grid-connected current includes the following steps:
s1, establishing MMC grid-connected current under the condition of unbalanced power grid voltage, and designing an expected global energy function of the MMC grid-connected system to obtain a PCHD model of the MMC grid-connected system under the condition of unbalanced power grid voltage, wherein the PCHD model is specific:
s11, defining the state variable asDefining input variables as Defining an output variable asWherein the positive sequence subsystem state variable is The negative sequence subsystem state variable is
The positive sequence subsystem output variable isThe negative sequence subsystem output variable is
Wherein L is eq Is the inductance of the bridge arm,respectively the dq axis positive and negative sequence components of the output voltage at the AC side,are the dq axis positive and negative sequence components of the ac side supply current, the dq axis positive and negative sequence components of the AC side power supply voltage are respectively;
s12, establishing a PCHD model-based MMC grid-connected current state equation based on the state variable, the input variable and the output variable in the step S11, designing an expected global energy function of the MMC grid-connected system, and obtaining the PCHD model of the MMC grid-connected system under the condition of unbalanced grid voltage, wherein the MMC grid-connected current state equation specifically comprises the following steps:
wherein J (x) is an interconnection matrix, R (x) is a damping matrix, g (x) is a port matrix, H (x) is an energy function, omega is fundamental angular frequency, R is bridge arm resistance,is a differential operator;
the desired global energy function is specifically:
wherein x is * Is the desired trajectory for x and is,respectively representing the dq axis expected positive sequence component and the negative sequence component of the alternating-current side power supply current, wherein D is a bridge arm inductance matrix;
the PCHD model of the MMC grid-connected system under the unbalanced power grid voltage specifically comprises the following steps:
wherein, J d (x) Expect an interconnection matrix for the system, R d (x) Desired damping matrix for the system, J a (x)、R a (x) Respectively an injected dissipation matrix and a damping matrix;
s2, constructing a PCHD model-based MMC grid-connected system PCHD model based on the step S1, and combining a consistency method to obtain a controlled variable, wherein the PCHD model-based MMC grid-connected passive consistency controller is based on the PCHD model under the condition of unbalanced power grid voltage:
s21, setting Laplace matrix L of positive sequence subsystem and negative sequence subsystem of MMC grid-connected system by combining consistency method 1 、L 2 :
Wherein Δ is L 1 、L 2 A is an adjacency matrix;
s22, taking the difference between the state variable and the expected balance point as zero as a control target, and designing a grid-connected current state variable error as follows:
wherein A is ij Is an interaction coefficient, α is an error coefficient, α =1 when the subsystems have the same desired trajectory; when the desired trajectories of the subsystems are different, α =0;
and then substituting the grid-connected current state variable error into a passive consistency control expected energy function based on the PCHD model:
and finally, combining with a PCHD model of the MMC grid-connected system to obtain a closed loop state equation of the MMC grid-connected system:
s23, combining an MMC grid-connected system closed loop state equation and an MMC grid-connected current state equation to obtain a passive consistency control law based on the PCHD model, namely obtaining a controlled variable, wherein the passive consistency control law based on the PCHD model specifically comprises the following steps:
wherein,the dq axis positive and negative sequence components of the AC side power supply voltage are respectively the obtained control quantity r a11 、r a12 、r a21 、r a22 For passive controller coefficients, A 1 、A 2 、B 1 、B 2 、C 1 、C 2 、D 1 、D 2 Respectively positive sequence control variable and negative sequence control variable;
s3, processing the control quantity by adopting a pulse modulation method to obtain a corresponding trigger pulse signal;
and S4, controlling the switching states of the converters of the bridge arm sub-modules of each phase of the MMC according to the trigger pulse signals.
The present embodiment applies the above method, as shown in fig. 2, including the following steps:
step 1: the three-phase MMC circuit structure and the topological diagram of the sub-modules are shown in figure 3, and the MMC grid-connected current positive and negative sequence sub-system dynamic equations under dq rotation coordinate system obtained from figure 3 are respectively
Where ω is the fundamental angular frequency, L eq Is the bridge arm inductance, R is the bridge arm resistance,respectively, an AC side output voltage u rj (j = a, b, c) positive and negative sequence components of dq axes,are respectively an AC side supply current i j (j = a, b, c) positive and negative sequence components of dq axes,are respectively an AC side supply voltage u j (j = a, b, c) positive and negative sequence components of dq axes,t is time, which is a differential operator.
Selecting a state variable x, an input variable u and an output variable y as follows:
designing an orthodefinite quadratic energy function H (x) as
Performing equivalent transformation on MMC grid-connected current positive and negative sequence subsystem dynamic equations (1) and (2) to obtain an MMC grid-connected current state equation as follows:
The design of the passivity MMC grid-connected system expected energy function based on the PCHD model specifically comprises the following steps:
and D is a bridge arm inductance matrix.
Introducing a state feedback control law
u 1 =δ(x 1 ) (7)
u 2 =δ(x 2 ) (8)
The PCHD model of the MMC grid-connected system under the voltage unbalance obtained by respectively replacing the formula (7) and the formula (8) with the formula (5) is specifically as follows:
in the formula, J d (x)=J(x)+J a (x) Expect an interconnection matrix for the system, satisfyR d (x)=R(x)+R a (x) Expect a damping matrix for the system, satisfyJ a (x)、R a (x) Respectively an injected dissipation matrix and a damping matrix.
The dissipation inequality can be derived from equations (4) and (9):
the left side of the equation (10) is increment of the whole MMC grid-connected current system, the right side is external supply energy, and the theory of passivity shows that: mapping u → x is strictly passive in output, and the MMC grid-connected current system has passive characteristics.
And 2, step: setting MMC grid-connected system positive and negative sequence subsystems by combining consistency methodLaplace matrix L 1 、L 2 :
In the formula: l is ij Is a matrix L 1 、L 2 The value of the node (i, j) is L 1 、L 2 A is an adjacency matrix.
And (3) designing a grid-connected current state variable error by taking the difference between the state variable and the expected balance point as zero as a control target:
in the formula,
when the subsystems have the same desired trajectory, α =1; when the subsystem expects different trajectories, α =0.
Substituting the equation (11) into equation (6) to obtain the PCHD model-based passive consistency control expected energy function specifically as follows:
combining with a PCHD model of the MMC grid-connected system to obtain a closed-loop equation of the MMC grid-connected system, wherein the closed-loop equation is as follows:
wherein, J d (x)=J(x)+J a (x) Interconnection matrix desired for the system, R d (x)=R(x)+R a (x) Damping matrix desired for the system, J a (x)、R a (x) Respectively an injected dissipation matrix and a damping matrix.
The passive consistency control law based on the PCHD model can be obtained by combining the vertical type (5), the formula (12) and the formula (13):
in the formula,
the equations (14) and (15) can ensure that the closed-loop control system can realize synchronous progressive tracking of the desired target of the MMC positive-sequence subsystem and the MMC negative-sequence subsystem on the premise of global progressive 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
Simulation model parameter/unit | Numerical value |
Number of submodules n/ | 36 |
Submodule capacitor C/mF | 9 |
Bridge arm inductance L/mH | 60 |
Bridge arm resistance R/omega | 6 |
Rated voltage u at AC side k /V | 100 |
Frequency f/Hz of AC system | 50 |
DC side voltage U dc /kV | 180 |
AC side inductor L g /mH | 25.5 |
Rated active power P/MW | 180 |
And carrying out simulation test by adopting an MMC grid-connected current passive consistency control method based on a PCHD model under the condition of unbalanced power grid voltage. When t =0.2s is set, the alternating-current side of the MMC has an a-phase grounding fault, when t =0.3s, the system is stably recovered, and the simulation results of the currents of the d-axis and the q-axis of the positive sequence and the negative sequence of the MMC are shown in figures 4 a-4 d. FIG. 4a is a positive sequence d-axis current waveform; FIG. 4b is a positive sequence q-axis current waveform; FIG. 4c is a negative sequence d-axis current waveform; fig. 4d negative sequence q-axis current waveform. The analysis shows that the method can realize the rapid tracking of the expected positive sequence current track and the rapid inhibition of the negative sequence current under the conditions of power grid voltage balance and single-phase earth fault; by combining a consistency method, the adjustment time of the track tracking expected by the positive sequence current and the negative sequence current is about 6.8ms, the synchronous tracking of the positive sequence subsystem and the negative sequence subsystem is realized, and the tracking steady-state error is small.
Claims (6)
1. A passive consistency control method for modular multilevel grid-connected current is characterized by comprising the following steps:
s1, establishing MMC grid-connected current under the condition of unbalanced power grid voltage, and designing an expected global energy function of an MMC grid-connected system to obtain a PCHD model of the MMC grid-connected system under the condition of unbalanced power grid voltage;
s2, constructing a PCHD model-based MMC grid-connected system PCHD model based on the established PCHD model in the step S1, and combining a consistency method to obtain a controlled variable;
s3, processing the control quantity by adopting a pulse modulation method to obtain a corresponding trigger pulse signal;
s4, controlling the switching state of a converter of each phase of bridge arm submodule of the MMC according to the trigger pulse signal;
the step S1 specifically includes the steps of:
s11, defining the state variable asDefining input variables as Defining an output variable asWherein the positive sequence subsystem state variable is Negative sequence subsystem state variables of
The positive sequence subsystem output variable isThe negative sequence subsystem output variable is
Wherein L is eq Is the inductance of the bridge arm,respectively the dq axis positive and negative sequence components of the output voltage at the AC side,are the dq axis positive and negative sequence components of the ac side supply current, the dq axis positive and negative sequence components of the AC side power supply voltage are respectively;
s12, establishing an MMC grid-connected current state equation based on the PCHD model based on the state variable, the input variable and the output variable in the step S11, designing an expected global energy function of the MMC grid-connected system, and obtaining the PCHD model of the MMC grid-connected system under the condition of unbalanced power grid voltage;
the MMC grid-connected current state equation specifically comprises the following steps:
wherein J (x) is an interconnection matrix, R (x) is a damping matrix, g (x) is a port matrix, H (x) is an energy function, omega is fundamental angular frequency, R is bridge arm resistance,is a differential operator;
the expected global energy function is specifically:
wherein x is * Is the desired trajectory for x and is,respectively representing the dq axis expected positive sequence component and the negative sequence component of the alternating-current side power supply current, wherein D is a bridge arm inductance matrix;
the step S2 specifically includes the steps of:
s21, setting Laplace matrix L of a positive sequence subsystem and a negative sequence subsystem of the MMC grid-connected system by combining a consistency method 1 、L 2 ;
S22, taking the difference between the state variable and the expected balance point as a control target, substituting the grid-connected current state variable error into a PCHD model-based passive consistency control expected energy function, and combining an MMC grid-connected system PCHD model to obtain an MMC grid-connected system closed loop state equation;
and S23, combining an MMC grid-connected system closed loop state equation and an MMC grid-connected current state equation to obtain a passive consistency control law based on the PCHD model, namely obtaining the controlled variable.
2. The method for controlling the passive consistency of the modular multilevel grid-connected current according to claim 1, wherein the PCHD model of the MMC grid-connected system under the unbalanced grid voltage specifically comprises:
wherein, J d (x) Expect an interconnection matrix for the system, R d (x) Desired damping matrix for the system, J a (x)、R a (x) Respectively an injected dissipation matrix and a damping matrix.
4. The passive consistency control method for the modular multilevel grid-connected current according to claim 3, wherein the grid-connected current state variable error specifically comprises:
wherein A is ij Is an interaction coefficient, α is an error coefficient, α =1 when the subsystems have the same desired trajectory; when the subsystems expect different trajectories, α =0.
6. the method for controlling the passive consistency of the modular multilevel grid-connected current according to claim 5, wherein the passive consistency control law based on the PCHD model specifically comprises the following steps:
wherein,the dq axis positive and negative sequence components of the AC side power supply voltage are respectively the obtained control quantity r a11 、r a12 、r a21 、r a22 Is a coefficient of a passive controller, A 1 、A 2 、B 1 、B 2 、C 1 、C 2 、D 1 、D 2 Positive sequence and negative sequence control variables, respectively.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
CN202110734879.2A CN113346781B (en) | 2021-06-30 | 2021-06-30 | Passive consistency control method for grid-connected current of modular multilevel converter |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
CN202110734879.2A CN113346781B (en) | 2021-06-30 | 2021-06-30 | Passive consistency control method for grid-connected current of modular multilevel converter |
Publications (2)
Publication Number | Publication Date |
---|---|
CN113346781A CN113346781A (en) | 2021-09-03 |
CN113346781B true CN113346781B (en) | 2022-11-18 |
Family
ID=77481691
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
CN202110734879.2A Active CN113346781B (en) | 2021-06-30 | 2021-06-30 | Passive consistency control method for grid-connected current of modular multilevel converter |
Country Status (1)
Country | Link |
---|---|
CN (1) | CN113346781B (en) |
Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN110212798A (en) * | 2019-06-24 | 2019-09-06 | 上海电力学院 | A kind of circulation inhibition method of Modular multilevel converter |
Family Cites Families (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN108021719A (en) * | 2016-10-29 | 2018-05-11 | 南京理工大学 | A kind of wind farm grid-connected passive control method |
CN111668867A (en) * | 2019-03-05 | 2020-09-15 | 南京理工大学 | Passive sliding mode control method for wind power plant through VSC-HVDC system grid connection |
CN111327219B (en) * | 2020-02-25 | 2021-01-12 | 上海电力大学 | Passive consistency control method for restraining circulating current of modular multilevel converter |
-
2021
- 2021-06-30 CN CN202110734879.2A patent/CN113346781B/en active Active
Patent Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN110212798A (en) * | 2019-06-24 | 2019-09-06 | 上海电力学院 | A kind of circulation inhibition method of Modular multilevel converter |
Also Published As
Publication number | Publication date |
---|---|
CN113346781A (en) | 2021-09-03 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
CN107123981B (en) | Flexible direct current and direct current power grid electromechanical transient simulation method and system based on MMC | |
CN111541262B (en) | MMC frequency coupling impedance modeling method under control of model pre-determination alternating voltage | |
Song et al. | Analysis of middle frequency resonance in DFIG system considering phase-locked loop | |
CN110707958B (en) | Modulation wave interval division-based midpoint voltage control method | |
CN110212798B (en) | Circulating current restraining method of modular multilevel converter | |
CN110212799B (en) | Passive backstepping control method for restraining circulating current of modular multilevel converter | |
CN108280271A (en) | THE UPFC equivalent modeling method based on switch periods average principle | |
CN110365051A (en) | A kind of virtual synchronous motor control method of adaptive instruction filtering inverting | |
CN114337343A (en) | Method and device for establishing MMC broadband three-port frequency coupling impedance model | |
CN114696334A (en) | Cascade H-bridge STATCOM phase-to-phase voltage balance control method based on feedforward compensation amount calculation | |
Meersman et al. | The influence of grid-connected three-phase inverters on voltage unbalance | |
CN110176770A (en) | The control method of MMC type Active Power Filter-APF when unbalanced source voltage | |
CN110048442B (en) | Differential smooth nonlinear control method and device for modular multilevel converter | |
CN113346781B (en) | Passive consistency control method for grid-connected current of modular multilevel converter | |
CN112003318A (en) | Wind power grid-connected inverter direct-current bus voltage control method | |
CN115811097A (en) | Voltage quality optimization method based on virtual oscillator control | |
CN111969643B (en) | Differential flat control method for MMC-HVDC (multi-media voltage direct current) supplying power to passive network under asymmetric fault | |
CN113346779B (en) | Grid-connected current passive control method for modular multilevel converter | |
CN113328644B (en) | Passive control method for capacitor voltage fluctuation of modular multilevel converter | |
Shuang et al. | A feedback linearization based control strategy for VSC-HVDC transmission converters | |
CN113765345B (en) | Method for suppressing capacitor voltage fluctuation of modularized multi-level converter | |
Lv et al. | Multi-harmonic Linearization Based Small-Signal Impedance Modeling of a Modular Multilevel Converter With DSOGI-PLL | |
Chen et al. | AC impedance model and resonance suppression method of multilevel converter | |
Zhang et al. | Passive Sliding Mode Control Strategy for Modular Multilevel Matrix Converters | |
Min et al. | Research on High Performance Interface Method for Simulation of HVDC Transmission Model of Large Power Grid |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
PB01 | Publication | ||
PB01 | Publication | ||
SE01 | Entry into force of request for substantive examination | ||
SE01 | Entry into force of request for substantive examination | ||
GR01 | Patent grant | ||
GR01 | Patent grant |