CN112039106A - Method for restraining DC voltage fluctuation based on MMC virtual capacitor - Google Patents

Method for restraining DC voltage fluctuation based on MMC virtual capacitor Download PDF

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CN112039106A
CN112039106A CN202010710072.0A CN202010710072A CN112039106A CN 112039106 A CN112039106 A CN 112039106A CN 202010710072 A CN202010710072 A CN 202010710072A CN 112039106 A CN112039106 A CN 112039106A
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CN112039106B (en
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李清
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Maintenance and Test Center of Extra High Voltage Power Transmission Co
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/36—Arrangements for transfer of electric power between ac networks via a high-tension dc link
    • 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
    • H02M1/32—Means for protecting converters other than automatic disconnection
    • 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
    • H02J3/36—Arrangements for transfer of electric power between ac networks via a high-tension dc link
    • H02J2003/365—Reducing harmonics or oscillations in HVDC
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/60—Arrangements for transfer of electric power between AC networks or generators via a high voltage DC link [HVCD]

Abstract

The invention discloses a method for inhibiting DC voltage fluctuation based on MMC virtual capacitors, which is characterized in that electrical parameters of an MMC are controlled through a preset control strategy, the control strategy is equivalent to a virtual capacitor with adjustable capacitance, and the virtual coefficient of the virtual capacitor is adjusted according to the amplitude of voltage fluctuation so as to inhibit the DC voltage fluctuation. The invention has the beneficial effects that: by presetting the control strategy in the MMC, the converter and the virtual capacitor can be made to show a physical behavior similar to that of a converter with a capacitor with adjustable size connected in parallel with a dc supply network, and the virtual capacitor represents the behavior of the MMC after the control strategy provided by the invention. Specifically, the virtual coefficient is adjusted to change the size of the virtual capacitor, so that the inertia of the direct-current power supply network is influenced, the capability of the direct-current power supply network for inhibiting voltage fluctuation can be enhanced, and the stability of the direct-current power supply network is improved.

Description

Method for restraining DC voltage fluctuation based on MMC virtual capacitor
Technical Field
The invention relates to the technical field of flexible direct current transmission, in particular to a method for inhibiting DC voltage fluctuation based on an MMC virtual capacitor.
Background
A modular multilevel converter (modular multilevel converter mmc) is a current converter topology commonly used in flexible dc power transmission systems. The converter commonly used in the high-voltage direct-current transmission project at present is a VSC, the converter comprises a large capacitor connected with a DC power grid, the inertia of the DC power grid depends on the size of the capacitor connected with the DC power grid, if a large capacitor is connected with the DC power grid, the DC power grid has higher inertia, conversely, if the connected capacitor is smaller, the inertia of the DC power grid is smaller, but the voltage of the capacitor end is coupled with the voltage of the DC power transmission network, which is a prominent disadvantage, besides, the output signal of the VSC is different from the ideal signal greatly, and the ideal signal can be obtained through multiple filtering.
For dc systems, the dynamic variation of the dc voltage depends on the amount of energy stored in the system capacitor, and according to the relevant literature, for a typical MMC system, it is able to maintain the dc voltage constant for only 40ms after voltage fluctuations occur, which is quite detrimental to the operation of the system. In the prior art, part of MMC control strategies are not energy-based, when a voltage difference is generated between a bridge arm voltage of a converter and a direct-current power supply network, a DC power supply network automatically adjusts power to reduce the voltage difference, and power exchange between a capacitor in the bridge arm and the DC power supply network is based on the change of the bridge arm capacitance tracking DC power supply network voltage, so that no additional control component is needed, and because no corresponding control component exists, part of variables in this type of MMC are not controlled, which results in the loss of converter robustness. In addition, some of the MMC control strategies in the prior art are based on energy MMC control, which can control the internal energy of the MMC by temporarily applying a mismatch between dc power and ac power, however, this type of converter is disadvantageous for decoupling the sub-module terminal voltage from the dc supply network voltage and cannot effectively suppress the voltage fluctuations of the dc supply network.
In summary, the existing converter and the control method thereof cannot effectively manage the internal energy of the MMC, and cannot utilize the energy to provide a stable suppression effect on the voltage fluctuation of the dc supply network.
Disclosure of Invention
Aiming at the problems, the invention provides a method for inhibiting DC voltage fluctuation based on an MMC virtual capacitor, which can convert direct current into alternating current or convert alternating current into direct current. The method mainly solves the problem that the existing MMC control strategy cannot provide stable inhibition effect on the voltage fluctuation of a direct-current power supply network.
In order to solve the technical problems, the technical scheme of the invention is as follows:
the method comprises the steps of controlling electrical parameters of the MMC through a preset control strategy, enabling the control strategy to be equivalent to a virtual capacitor with adjustable capacitance, and adjusting a virtual coefficient of the virtual capacitor according to the amplitude of voltage fluctuation so as to suppress the DC voltage fluctuation.
The suppression system based on the MMC virtual capacitor to the DC voltage fluctuation is further provided, the electrical parameters of the MMC are controlled through a preset control system, the control system is equivalent to a virtual capacitor with the adjustable capacitance, and the virtual coefficient of the virtual capacitor is adjusted according to the voltage fluctuation amplitude. The control system comprises an energy reference value calculation module, an internal energy control module, a direct current voltage control module, a PI control module, a sliding mode direct power control module and a current control module; the energy reference value calculation module is used for calculating the internal energy reference value of MMC, the internal energy control module is used for calculating the absorbed power reference value of virtual capacitance, the direct current voltage control module is used for calculating the reference value of alternating current power, the PI control module is used for calculating the first intermediate current amount reference quantity related to the direct current power, the sliding mode direct power control module is used for calculating the second intermediate current amount reference value related to the alternating current power, and the current control module is used for calculating the intermediate current variable.
A computer-readable storage medium is also proposed, which stores a computer program, wherein the computer program causes a computer to perform the method of the above-mentioned suppression method.
The invention has the beneficial effects that: by presetting the control strategy in the MMC, the converter and the virtual capacitor can be made to show a physical behavior similar to that of a converter with a capacitor with adjustable size connected in parallel with a dc supply network, and the virtual capacitor represents the behavior of the MMC after the control strategy provided by the invention. Specifically, the virtual coefficient is adjusted to change the size of the virtual capacitor, so that the inertia of the direct-current power supply network is influenced, the capability of the direct-current power supply network for inhibiting voltage fluctuation can be enhanced, and the stability of the direct-current power supply network is improved.
Drawings
FIG. 1 is a flow chart of a disclosed suppression method according to an embodiment of the present invention;
FIG. 2 is a main control block diagram of a suppression system according to a second embodiment of the present invention;
FIG. 3 is a DC voltage control diagram of a suppression method according to an embodiment of the present invention;
FIG. 4 is a power flow diagram of a suppression method according to an embodiment of the present invention;
fig. 5 is an equivalent circuit of the suppression method according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention clearer and clearer, the following detailed description of the present invention is provided with reference to the accompanying drawings and detailed description. 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 should be further noted that, for the convenience of description, only some but not all of the relevant aspects of the present invention are shown in the drawings.
Example one
According to the figure 1, the embodiment provides a method for suppressing DC voltage fluctuation based on an MMC virtual capacitor, wherein electrical parameters of the MMC are controlled through a preset control strategy, the control strategy is equivalent to a virtual capacitor with adjustable capacitance, and a virtual coefficient of the virtual capacitor is adjusted according to the amplitude of voltage fluctuation to suppress DC voltage fluctuation.
The control strategy comprises the following steps:
step one, defining a point where a converter is connected with a direct current power supply network as a common connection point, taking a square value of a voltage actual value of the common connection point, a square value of a voltage nominal value of the common connection point, an MMC internal energy nominal value and a virtual inertia coefficient with adjustable size as input, and outputting an MMC internal energy reference value, wherein the calculation method comprises the following steps:
Figure BDA0002596201040000031
wherein the content of the first and second substances,
Figure BDA0002596201040000032
reference value for MMC internal energy, CtotTo concentrate the capacitance value of the capacitor, vdcIs the actual value of the voltage of the point of common connection, vdc0Is a voltage reference value of the common connection point,
Figure BDA0002596201040000033
is the nominal value of the MMC internal energy, kVIIs the virtual inertia coefficient.
Step two, the MMC internal energy reference value and the MMC internal energy actual value are used as input, wherein an energy tracking part can be realized by any controller, so that w∑Following
Figure BDA0002596201040000034
In a variation of (1) are
Figure BDA0002596201040000035
The basic method can be realized by using a PI controller, and for calculating the absorbed power reference value of the virtual capacitor, the calculation method is as follows:
Figure BDA0002596201040000036
wherein, w∑Is the actual value of internal energy, CeqThe capacitance of the polymer capacitor is Ceq＝6Ctot，
Figure BDA0002596201040000037
A reference value of power is absorbed for the virtual capacitance.
Step three, as shown in fig. 3, taking a square value of the actual voltage value of the common connection point and a square value of the reference voltage value of the common connection point as input, and outputting a reference value of the ac power, wherein the calculation method is as follows:
Figure BDA0002596201040000038
wherein the content of the first and second substances,
Figure BDA0002596201040000039
is a reference value of AC power, Fv(s) is a PI controller, and the PI controller is a power amplifier,
Figure BDA00025962010400000310
which is the voltage reference of the common connection point, s refers to the frequency domain,
Figure BDA00025962010400000311
Kpv＝ζwnC∑，
Figure BDA00025962010400000312
C∑an equivalent capacitance of a DC circuit having C∑＝Cdc+CVI，wnFor natural frequency, it is usually taken
Figure BDA00025962010400000313
And TrFor ideal response time, ζ is 0.707 as damping ratio.
Step four, as shown in fig. 4, inputting a difference between the reference value of the dc power and the actual value of the dc power, and outputting a first reference amount of intermediate current related to the dc power, wherein the calculation method comprises the following steps:
reference value of DC power
Figure BDA0002596201040000041
Actual value of DC power Pdc＝vdcidiffi
Figure BDA0002596201040000042
Wherein h (v) is a PI controller,
Figure BDA0002596201040000043
idiffithe reference value and the actual value of the common-mode component of the bridge arm current are respectively.
Figure BDA0002596201040000044
Kpv,pdcProportional coefficient of PI controller, Kiv,pdcIs the PI controller integration coefficient.
Step five, taking the difference value between the alternating current power reference value and the alternating current power actual value and the difference value between the alternating current reactive power reference value and the alternating current reactive power actual value as input, and outputting a second intermediate current amount reference value related to the alternating current power, wherein the calculation method comprises the following steps:
Pac＝vgdigd
Figure BDA0002596201040000045
Figure RE-GDA0002719740880000046
Figure RE-GDA0002719740880000047
Figure RE-GDA0002719740880000048
wherein, PacIs the actual value of the AC power, vgdIs the direct component of the AC voltage, igdIs the direct component of the alternating current, e is the difference between the actual power of the alternating current and its reference value,
Figure RE-GDA0002719740880000049
the derivative of the respective quantity with respect to time is indicated,
Figure RE-GDA00027197408800000410
for reference values of the direct component of the alternating current, sign being a sign function, Kpv、KivTo solve separately
Figure RE-GDA00027197408800000411
The proportional and integral constants involved are,
Figure RE-GDA00027197408800000412
Figure RE-GDA00027197408800000413
both indicate the derivation of the content in brackets,
Figure RE-GDA00027197408800000414
Qacrespectively an ac reactive power reference value and an actual value,
Figure RE-GDA00027197408800000415
presentation pair
Figure RE-GDA00027197408800000416
Integration is performed. Ki,qacTo solve for
Figure RE-GDA00027197408800000417
The integration constants involved.
Step six, inputting the first intermediate current quantity reference quantity and the second intermediate current variable, and outputting an intermediate current variable, wherein the calculation method comprises the following steps:
Figure BDA00025962010400000421
Figure BDA0002596201040000051
Figure BDA0002596201040000052
Figure BDA0002596201040000053
Figure BDA0002596201040000054
Figure BDA0002596201040000055
Figure BDA0002596201040000056
wherein the content of the first and second substances,
Figure BDA0002596201040000057
Figure BDA0002596201040000058
is composed of
Figure BDA0002596201040000059
Reference values of the direct axis and quadrature axis components after park transformation, q represents the quadrature axis, d represents the direct axis,
Figure BDA00025962010400000510
is a reference value for the differential mode component of the bridge arm voltage,
Figure BDA00025962010400000511
igqare respectively a crossReference and actual values, v, of AC-AC component of the flowgqFor the AC-voltage AC-axis component, p (v) is a PI controller, LarmIs bridge arm inductance, LfThe inductance on the ac side, w is the angular velocity,
Figure BDA00025962010400000512
is the common-mode quantity of the bridge arm voltages,
Figure BDA00025962010400000513
is the equivalent voltage of the upper bridge arm,
Figure BDA00025962010400000514
is the equivalent voltage of the lower bridge arm,
Figure BDA00025962010400000515
and
Figure BDA00025962010400000516
the voltage values of the upper bridge arm and the lower bridge arm centralized capacitors are respectively,
Figure BDA00025962010400000517
and
Figure BDA00025962010400000518
is the duty ratio of the upper bridge arm and the lower bridge arm,
Figure BDA00025962010400000519
for an AC phase voltage, RfIs an AC side resistor, RarmIs a resistance of a bridge arm, and is,
Figure BDA00025962010400000520
is an alternating phase current.
In general, the reference values are denoted with a prime and the actual values are denoted without a prime.
As shown in FIG. 5, it can be observed that there is an adjustable capacitance CVIVirtual capacitor C ofVIIn parallel with the dc supply network (for convenience of presentation, C)VIBoth physically and physically actual capacitorsThe magnitude of the capacitance). Wherein "virtual" is used to indicate that the capacitor is not a real physical capacitor present in the converter, the present invention can make the converter and the virtual capacitor show a physical behavior similar to that of a converter with a capacitor with adjustable size connected in parallel with a dc power supply network by presetting a control strategy in the MMC, and the virtual capacitor shows the behavior of the MMC after the control strategy provided by the present invention. Particularly, the virtual coefficient is adjusted to change the size of the virtual capacitor, so that the inertia of the direct-current power supply network is influenced, the capability of the direct-current power supply network for inhibiting voltage fluctuation is enhanced, and the stability of the direct-current power supply network is improved.
Example two
The utility model provides an inhibition system to DC voltage fluctuation based on virtual electric capacity of MMC, controls MMC's electrical parameter through predetermined control system, will control system equivalence is a virtual condenser of electric capacity size adjustable, according to voltage fluctuation's amplitude adjustment virtual condenser's virtual coefficient.
As shown in fig. 2, the control system includes an energy reference value calculation module, an internal energy control module, a dc voltage control module, a PI control module, a sliding mode direct power control module, and a current control module;
the energy reference value calculation module is used for calculating the MMC's internal energy reference value, internal energy control module is used for calculating virtual capacitance's absorbed power reference value, direct current voltage control module is used for calculating alternating current power's reference value, PI control module is used for calculating the first intermediate current volume reference quantity relevant with direct current power, the direct power control module of slipform is used for calculating the second intermediate current volume reference value relevant with alternating current power, current control module is used for calculating intermediate current variable.
The calculation methods of the six modules are respectively implemented corresponding to the steps from one to six in the first embodiment.
EXAMPLE III
A computer-readable storage medium storing a computer program, wherein the computer program causes a computer to perform the method of embodiment one.
The above embodiments are only for illustrating the technical concept and features of the present invention, and the purpose thereof is to enable those skilled in the art to understand the contents of the present invention and implement the present invention accordingly, and not to limit the protection scope of the present invention accordingly. All equivalent changes or modifications made in accordance with the spirit of the present disclosure are intended to be covered by the scope of the present disclosure.

Claims (10)

1. The method for restraining the DC voltage fluctuation based on the MMC virtual capacitor is characterized in that the electrical parameters of the MMC are controlled through a preset control strategy, the control strategy is equivalent to a virtual capacitor with adjustable capacitance, and the virtual coefficient of the virtual capacitor is adjusted according to the voltage fluctuation amplitude so as to restrain the DC voltage fluctuation.
2. The MMC virtual capacitor-based suppression method for DC voltage fluctuation according to claim 1, wherein the control strategy comprises defining a point where a converter is connected to a DC power supply network as a common connection point, and outputting an MMC internal energy reference value by taking a square value of a voltage actual value of the common connection point, a square value of a voltage nominal value of the common connection point, an MMC internal energy nominal value and a virtual inertia coefficient with adjustable magnitude as inputs, wherein the calculation method comprises the following steps:
Figure FDA0002596201030000011
wherein the content of the first and second substances,
Figure FDA0002596201030000012
reference value for MMC internal energy, CtotTo concentrate the capacitance value of the capacitor, vdcIs the actual value of the voltage of the point of common connection, vdc0Is the nominal value of the voltage at the point of common connection,
Figure FDA0002596201030000013
is the nominal value of the MMC internal energy, kVIIs the virtual inertia coefficient.
3. The MMC virtual capacitor-based suppression method for DC voltage fluctuations of claim 2, wherein the control strategy further comprises taking as input the MMC internal energy reference value and the MMC internal energy actual value, the energy tracking portion being controlled w by the PI controller∑Following
Figure FDA0002596201030000014
In a variation of (1) are
Figure FDA0002596201030000015
For calculating the absorbed power reference value of the virtual capacitor, the calculation method is as follows:
Figure FDA0002596201030000016
wherein, w∑Is the actual value of internal energy, CeqThe capacitance of the polymer capacitor is Ceq＝6Ctot，
Figure FDA0002596201030000017
A reference value of power is absorbed for the virtual capacitance.
4. The MMC virtual capacitor-based suppression method for DC voltage fluctuations of claim 3, wherein the control strategy further comprises outputting a reference value of AC power using a square of the actual value of the voltage at the point of common connection and a square of the reference value of the voltage at the point of common connection as inputs by:
Figure FDA0002596201030000018
wherein the content of the first and second substances,
Figure FDA0002596201030000019
is a reference value of AC power, Fv(s) is a PI controller, and the PI controller is a power amplifier,
Figure FDA00025962010300000110
is the voltage reference of the common connection point.
5. The MMC virtual capacitor-based suppression method for DC voltage fluctuation of claim 4, wherein the control strategy further comprises inputting a difference between a DC power reference value and a DC power actual value, and outputting a first intermediate current amount reference related to the DC power, the calculation method comprises:
reference value of DC power
Figure FDA00025962010300000111
Actual value of DC power Pdc＝vdcidiffi
Figure FDA0002596201030000021
Wherein h (v) is a PI controller,
Figure FDA0002596201030000022
idiffithe reference value and the actual value of the common-mode component of the bridge arm current are respectively.
6. The MMC virtual capacitor-based suppression method for DC voltage fluctuations of claim 5, wherein the control strategy further comprises outputting a second intermediary amperage reference associated with the AC power using as inputs the difference between the AC real power reference and the AC real power, and the difference between the AC reactive power reference and the AC real power, by:
Pac＝vgdigd
Figure RE-FDA0002719740870000023
Figure RE-FDA0002719740870000024
Figure RE-FDA0002719740870000025
Figure RE-FDA0002719740870000026
wherein, PacIs the actual value of the AC power, vgdIs the direct component of the AC voltage, igdIs the direct-axis component of the alternating current, e is the difference between the actual alternating power and the reference value,
Figure RE-FDA0002719740870000027
the derivative of the respective quantity with respect to time is indicated,
Figure RE-FDA0002719740870000028
for reference values of the direct component of the alternating current, sign being a sign function, Kpv、KivTo solve separately
Figure RE-FDA0002719740870000029
The proportional and integral constants involved are,
Figure RE-FDA00027197408700000210
Figure RE-FDA00027197408700000211
all indicate to carry out the content in bracketsThe derivation is carried out by the derivation,
Figure RE-FDA00027197408700000212
Qacrespectively an ac reactive power reference value and an actual value,
Figure RE-FDA00027197408700000213
presentation pair
Figure RE-FDA00027197408700000214
Integration is performed.
7. The MMC virtual capacitor-based suppression method for DC voltage fluctuations of claim 5, wherein the control strategy further comprises inputting the first intermediate current amount reference and the second intermediate current variable and outputting an intermediate current variable by:
Figure FDA00025962010300000215
Figure FDA00025962010300000216
Figure FDA00025962010300000217
Figure FDA0002596201030000031
Figure FDA0002596201030000032
Figure FDA0002596201030000033
Figure FDA0002596201030000034
wherein the content of the first and second substances,
Figure FDA0002596201030000035
is composed of
Figure FDA0002596201030000036
Reference values of the direct axis and quadrature axis components after park transformation, q represents the quadrature axis, d represents the direct axis,
Figure FDA0002596201030000037
is a reference value for the differential mode component of the bridge arm voltage,
Figure FDA0002596201030000038
igqreference and actual values, v, of quadrature-axis components of the alternating current, respectivelygqFor the quadrature component of the AC voltage, p (v) is a PI controller, LarmIs bridge arm inductance, LfThe inductance on the ac side, w is the angular velocity,
Figure FDA0002596201030000039
is the common modulus of the bridge arm voltages,
Figure FDA00025962010300000310
is the equivalent voltage of the upper bridge arm,
Figure FDA00025962010300000311
is the equivalent voltage of the lower bridge arm,
Figure FDA00025962010300000312
and
Figure FDA00025962010300000313
the voltage values of the upper bridge arm and the lower bridge arm centralized capacitors are respectively,
Figure FDA00025962010300000314
and
Figure FDA00025962010300000315
is the duty ratio of the upper bridge arm and the lower bridge arm,
Figure FDA00025962010300000316
for an AC phase voltage, RfIs an AC side resistor, RarmIs a resistance of a bridge arm, and is,
Figure FDA00025962010300000317
is an alternating phase current.
8. The utility model provides an inhibition system to DC voltage fluctuation based on virtual electric capacity of MMC which characterized in that, controls MMC's electrical parameter through predetermined control system, will control system is equivalent to a virtual condenser that electric capacity size is adjustable, according to voltage fluctuation's range adjustment virtual capacitor's virtual coefficient.
9. The MMC virtual capacitor-based suppression system for DC voltage fluctuations of claim 8, wherein the control system comprises an energy reference value calculation module, an internal energy control module, a DC voltage control module, a PI control module, a sliding mode direct power control module, and a current control module;
the energy reference value calculation module is used for calculating the MMC's internal energy reference value, internal energy control module is used for calculating virtual capacitance's absorbed power reference value, direct current voltage control module is used for calculating alternating current power's reference value, PI control module is used for calculating the first intermediate current volume reference quantity relevant with direct current power, the direct power control module of slipform is used for calculating the second intermediate current volume reference value relevant with alternating current power, current control module is used for calculating intermediate current variable.
10. A computer-readable storage medium, characterized in that the computer-readable storage medium stores a computer program, wherein the computer program causes a computer to perform the method of any one of claims 1 to 7.
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CN112803474A (en) * 2020-12-30 2021-05-14 国网黑龙江省电力有限公司电力科学研究院 Control method for enhancing stability of direct-current bus of energy router
CN113394824A (en) * 2021-06-29 2021-09-14 长江勘测规划设计研究有限责任公司 MMC alternating current active power rapid regulation and control method without direct current side disturbance
CN113433839A (en) * 2021-06-28 2021-09-24 杭州电子科技大学 Synchronous rectification Boost converter simulation circuit based on virtual inductor and virtual capacitor

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