CN113965057A - Coupling harmonic injection method for inhibiting voltage fluctuation of half-bridge MMC capacitor - Google Patents

Coupling harmonic injection method for inhibiting voltage fluctuation of half-bridge MMC capacitor Download PDF

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CN113965057A
CN113965057A CN202111205211.5A CN202111205211A CN113965057A CN 113965057 A CN113965057 A CN 113965057A CN 202111205211 A CN202111205211 A CN 202111205211A CN 113965057 A CN113965057 A CN 113965057A
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frequency
voltage
bridge arm
fluctuation
phase
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CN113965057B (en
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王一凡
王鋆鑫
许建中
武文
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North China Electric Power University
China Three Gorges Corp
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China Three Gorges Corp
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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
    • 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
    • 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
    • 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
    • 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]

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Abstract

A coupling harmonic injection method for inhibiting voltage fluctuation of a half-bridge MMC capacitor comprises the following steps: step 1: obtaining an expression of instantaneous power of a bridge arm containing second harmonic voltage after injection of double-frequency circulating current is considered, and establishing an optimized objective function on the basis of fundamental frequency and double-frequency fluctuation components of the instantaneous power of the bridge arm; step 2: determining the amplitude and phase of the double frequency circulating current and the triple frequency voltage injection according to the optimization result; and step 3: and generating a reference signal required by the controller according to the calculated amplitude and phase. The invention aims to provide a coupling harmonic injection method for inhibiting the fluctuation of the capacitance and the voltage of a half-bridge type MMC (Modular multilevel converter) in order to effectively inhibit the fluctuation of the bridge arm power of the MMC converter valve, reduce the fluctuation of the sub-module capacitance and further reduce the design requirement of the sub-module capacitance and the capacitance value, thereby reducing the sub-module capacitance volume and finally reducing the volume of the MMC.

Description

Coupling harmonic injection method for inhibiting voltage fluctuation of half-bridge MMC capacitor
Technical Field
The invention belongs to the technical field of power transmission, particularly relates to a flexible direct current power transmission technology, and particularly relates to a coupling harmonic injection method for inhibiting voltage fluctuation of a half-bridge MMC capacitor.
Background
Flexible direct current transmission (VSC-HVDC) is a new generation of direct current transmission technology following alternating current transmission, conventional direct current transmission. The flexible direct current transmission technology has the characteristics of independent active and reactive power adjustment, strong weak power grid access and low voltage ride through capability, low alternating current filtering, reactive power compensation requirements and the like. The Modular Multilevel Converter (MMC) has the characteristics of flexible control, module expansibility, low switching frequency, low harmonic content and the like. At present, MMC structures are adopted in Shanghai south-Virginia flexible direct current engineering, Nanao three-terminal flexible direct current engineering, Zhoushan five-terminal flexible direct current engineering, Xiamen +/-320 kV flexible direct current demonstration engineering and Zhang Bei direct current power grid engineering which are built in China.
However, compared with a conventional current source converter (LCC), the MMC has a problem of large volume and weight under the same capacity. Under the era background of the state of vigorously developing the open-sea wind power, the sending of the open-sea wind power through the MMC is one of the solutions generally accepted at present. Reducing the size and weight of the MMC contributes to reducing the construction costs of the offshore platform and the converter station itself. The MMC submodule capacitor occupies more than 1/2 of the submodule volume and is about 1/3 of the cost, so that the capacitor voltage fluctuation suppression strategy research is carried out to reduce the capacitor value design requirement, and the method has great theoretical and engineering significance.
Disclosure of Invention
The invention aims to provide a coupling harmonic injection method for inhibiting the fluctuation of the capacitance and the voltage of a half-bridge type MMC (Modular multilevel converter) in order to effectively inhibit the fluctuation of the bridge arm power of the MMC converter valve, reduce the fluctuation of the sub-module capacitance and further reduce the design requirement of the sub-module capacitance and the capacitance value, thereby reducing the sub-module capacitance volume and finally reducing the volume of the MMC.
A coupling harmonic injection method for inhibiting voltage fluctuation of a half-bridge MMC capacitor comprises the following steps:
step 1: obtaining an expression of instantaneous power of a bridge arm containing second harmonic voltage after injection of double-frequency circulating current is considered, and establishing an optimized objective function on the basis of fundamental frequency and double-frequency fluctuation components of the instantaneous power of the bridge arm;
step 2: determining the amplitude and phase of the double frequency circulating current and the triple frequency voltage injection according to the optimization result;
and step 3: and generating a reference signal required by the controller according to the calculated amplitude and phase.
In step 1, when obtaining an instantaneous power expression of the bridge arm containing the second harmonic voltage after the injection of the double frequency circulating current is considered, the method includes:
1) obtaining a bridge arm current expression considering second harmonic current injection;
2) obtaining a bridge arm voltage expression considering third harmonic voltage injection and second harmonic voltage;
3) and obtaining the instantaneous power of the bridge arm.
Wherein the bridge arm current considering second harmonic current injection can be expressed as:
Figure BDA0003306567570000021
wherein iau、ialRespectively an A-phase upper bridge arm current and a lower bridge arm current; omega is the fundamental angular frequency;
Figure BDA0003306567570000029
respectively a power factor angle and a second harmonic current phase angle; i is2Is the second harmonic current amplitude;
the bridge arm voltage considering the third harmonic voltage injection and the second harmonic voltage can be expressed as:
Figure BDA0003306567570000022
Figure BDA0003306567570000023
wherein U is3、
Figure BDA0003306567570000024
Respectively the amplitude and phase of the injected third harmonic voltage; i.e. icirIs the second harmonic current component;
defining the modulation ratio m as 2Um/UdcAccording to the conservation of the AC side power and the DC side power, I can be obtainedmAnd IdcThe following relationship is satisfied:
Figure BDA0003306567570000025
according to the definition of the above expression and the modulation ratio, the voltage and current expressions of the bridge arm can be simplified and expressed as follows:
Figure BDA0003306567570000026
wherein k is2And k3Respectively, the second harmonic injection coefficient and the third harmonic injection coefficient, c is a constant and has an expression of
Figure BDA0003306567570000027
From the above formula, the upper bridge arm instantaneous power PauCan be expressed as:
Figure BDA0003306567570000028
the specific expression of each secondary component in the above formula is as follows:
Figure BDA0003306567570000031
constant c is derived from the DC power PdcAnd a DC voltage UdcAnd (6) determining.
In the step 1, the fundamental frequency and the double-frequency fluctuation component of the instantaneous power of the bridge arm are used as the inhibition target, and when an optimization target function is established, for the phase A, the fundamental frequency and the double-frequency fluctuation of the instantaneous power of the bridge arm on the phase A are obtained according to the instantaneous power of the bridge arm on the phase A containing double-frequency circulation injection, so that the fluctuation amplitude is obtained;
establishing an objective function according to the obtained fundamental frequency of the instantaneous power of the A-phase bridge arm and the fluctuation amplitude of the double frequency fluctuation as follows:
Figure BDA0003306567570000032
wherein, | Pau_1I and I Pau_2I is the fundamental frequency of the instantaneous power of the bridge arm on the phase A and the fluctuation amplitude of the double frequency fluctuation respectively; k represents a weight coefficient of the secondary fluctuation of the capacitor voltage.
The fundamental frequency and double frequency fluctuation of the instantaneous power of the bridge arm on the A phase are as follows:
Figure BDA0003306567570000033
wherein, Pau_1And Pau_2Fundamental frequency and double frequency fluctuation of instantaneous power of an upper bridge arm of the phase A are respectively obtained;
to Pau_1And Pau_2Performing an identity transform to obtain:
Pau_1＝Aau_1sinωt+Bau_1cosωt
Figure BDA0003306567570000041
Pau_2＝Aau_2sin2ωt+Bau_2cos2ωt
Figure BDA0003306567570000042
obtaining P according to the identity transformation resultau_1And Pau_2The fluctuation amplitude is:
Figure BDA0003306567570000043
generating a reference signal according to the amplitude and the phase of the injection of the double frequency circulation and the triple frequency voltage, and realizing the coupling injection of the double frequency circulation and the triple frequency voltage by combining a modulation algorithm comprises the following steps:
amplitude phase k based on double frequency circulating current injection2、
Figure BDA0003306567570000044
And generating a reference signal in conjunction with a reference signal generator;
the reference signal is injected into the controller through the double frequency circulation to obtain a double frequency circulation modulation voltage signal Ucirj_ref(ii) a Using the obtained k3、
Figure BDA0003306567570000045
Optimal value is taken, and a frequency tripling voltage modulation signal U is obtained through a frequency tripling voltage injection controller3j_refFinally, the coupling injection of the double frequency circulation and the triple frequency voltage is realized by changing the modulation wave of the modulation algorithm.
Compared with the prior art, the invention has the following technical effects:
the invention takes the fundamental frequency and the double frequency fluctuation component of the instantaneous power as the suppression target, carries out the optimization design of the amplitude and the phase of the injected double frequency circulation, and finally injects the calculated double frequency circulation and the calculated triple frequency voltage into the three phases by changing the modulation wave signal. The method can effectively inhibit the fluctuation of the converter valve bridge arm power, further reduce the fluctuation of the sub-module capacitor voltage, further reduce the design requirement of the sub-module capacitor capacitance value, reduce the sub-module capacitor volume, and finally reduce the volume of the MMC, and has important significance for reducing the volume and weight of the MMC and further reducing the construction cost of an offshore platform and a converter station.
Drawings
The invention is further illustrated by the following examples in conjunction with the accompanying drawings:
FIG. 1 is a flow chart of the present invention;
fig. 2 is a system control block diagram of the present invention.
Detailed Description
As shown in fig. 1 and fig. 2, a method for injecting a coupling harmonic to suppress voltage fluctuation of a half-bridge MMC capacitor mainly includes the following steps:
step 1: and establishing an optimization objective function by taking the fundamental frequency and the double-frequency fluctuation component of the instantaneous power of the bridge arm as an inhibition objective.
In the embodiment of the invention, firstly, an expression of instantaneous power of a bridge arm containing second harmonic voltage after injection of frequency doubling circulation is deduced and considered, and then an optimized objective function is established.
1) And considering the instantaneous power expression of the bridge arm containing the second harmonic voltage after the injection of the frequency doubling circulation.
Since the MMC has three-phase symmetry during steady-state operation, the method is described by taking the phase a as an example, and the derivation method of the B, C two-phase formula is the same as that of the phase a, and the derivation is not repeated. The leg current considering the second harmonic current injection can be expressed as:
Figure BDA0003306567570000051
wherein iau、ialRespectively an A-phase upper bridge arm current and a lower bridge arm current; omega is the fundamental angular frequency;
Figure BDA0003306567570000052
respectively a power factor angle and a second harmonic current phase angle; i isdcIs direct current side current; i ismIs the amplitude of the alternating current side current; i is2The second harmonic current amplitude.
The bridge arm voltage considering the third harmonic voltage injection and the second harmonic voltage can be expressed as:
Figure BDA0003306567570000053
wherein u isau、ualRespectively an A-phase upper bridge arm voltage and a lower bridge arm voltage; u shapedcIs a direct current side voltage; u shapemIs the AC side voltage amplitude; u shape3、
Figure BDA0003306567570000054
Respectively the amplitude and phase of the injected third harmonic voltage; l is bridge arm inductance; i.e. icirIs the second harmonic current component. The second harmonic component in formula (1) is taken into formula (2) to obtain:
Figure BDA0003306567570000055
defining the modulation ratio m as 2Um/Udc. According to the conservation of the AC side power and the DC side power, I can be obtainedmAnd IdcThe following relationship is satisfied:
Figure BDA0003306567570000061
the bridge arm voltage and current expressions can be simplified according to the expression (4) and the definition of the modulation ratio. Because the upper and lower bridge arms are symmetrical when the MMC operates in a steady state and the operation characteristics are the same, the analysis is carried out by taking the upper bridge arm as an example:
Figure BDA0003306567570000062
wherein k is2And k3Respectively, the second harmonic injection coefficient and the third harmonic injection coefficient, c is a constant and has an expression of
Figure BDA0003306567570000063
As can be seen from the formula (6),constant c is derived from the DC power PdcAnd a DC voltage UdcAnd (6) determining. According to equation (5), the upper bridge arm instantaneous power PauCan be expressed as:
Figure BDA0003306567570000064
the specific expression of each sub-component in the formula (7) is shown in the formula (8)
Figure BDA0003306567570000065
2) And establishing an optimization objective function by taking the fundamental frequency and the double-frequency fluctuation component of the instantaneous power of the bridge arm as an inhibition objective. The main process is as follows:
the fundamental frequency and the double frequency fluctuation of the instantaneous power of the bridge arm on the phase A can be obtained by the formula (8), as shown in the formula (9):
Figure BDA0003306567570000066
p can be decomposed by orthogonalau_1And Pau_2The rewrite is:
Figure BDA0003306567570000071
Figure BDA0003306567570000072
from the formulae (10) and (11), P can be obtainedau_1And Pau_2The amplitude of (d) is:
Figure BDA0003306567570000073
the difficulty with the coupled harmonic injection strategy is how to choose the amplitude and phase of the injected harmonics. For a particular operating regime (m and
Figure BDA0003306567570000074
fixed), it requires determining the amplitude I of the second harmonic current2And phase
Figure BDA0003306567570000075
And amplitude U of third harmonic voltage3And phase
Figure BDA0003306567570000076
There are four variables in total. Since the injection harmonic amplitude satisfies equation (6), it can be converted into the determination of k2、k3、
Figure BDA0003306567570000077
And
Figure BDA0003306567570000078
to maximally suppress the capacitor voltage fluctuation, it is required to reduce the fundamental frequency and the second harmonic component in the bridge arm power as much as possible, and therefore the objective function is defined herein as
Figure BDA0003306567570000079
Where k represents the weighting factor of the doubled power fluctuation. Since the double frequency power fluctuation has less influence on the overall power fluctuation amplitude, the k value is set to 0.54 here. It should be noted that the value of k is not fixed, and can be adjusted appropriately according to actual conditions.
Step 2: and performing global optimization by taking the objective function minimization as an objective to obtain the optimal amplitude and phase of double frequency circulating current and triple frequency voltage injection.
In the embodiment of the invention, global optimization is carried out by taking objective function minimization as a target, and k is determined according to different modulation ratios m2、
Figure BDA00033065675700000710
k3、
Figure BDA00033065675700000711
Optimal values of the four variables. It should be noted that the present invention does not limit the optimization method, and the user can select the optimization method according to the actual situation.
It will be appreciated by those skilled in the art that since the objective function is based on the capacitor voltage fluctuation, its minimized solution can achieve a minimization of the capacitor voltage fluctuation, i.e. if the amplitude and phase of the optimal solution are injected, the objective can be achieved, in particular, by designing the parameter k2、
Figure BDA00033065675700000712
k3、
Figure BDA00033065675700000713
Can realize suppression of the fluctuation of the capacitor voltage.
And step 3: and generating a reference signal according to the injected amplitude and phase, and combining a modulation algorithm to realize the injection of double frequency circulation and triple frequency voltage.
In the embodiment of the invention, the optimal amplitude and phase of double frequency circulating current injection are obtained, namely k is obtained2、
Figure BDA0003306567570000081
An optimal value, after which a reference signal i can be generated in conjunction with a reference signal generator2fd_refAnd i2fq_refWherein i is2fd_refReference signal, i, for d-axis double frequency circulating injection controller2fq_refA reference signal for the q-axis double frequency circulating current injection controller. The reference signal is injected into the controller through the double frequency circulation to obtain a double frequency circulation modulation voltage signal Ucirj_ref(ii) a Using the obtained k3、
Figure BDA0003306567570000082
Optimal value is taken, and a frequency tripling voltage modulation signal U is obtained through a frequency tripling voltage injection controller3j_refFinally, the double frequency circulation and the third frequency circulation are realized by changing the modulation wave of the modulation algorithmAnd coupling and injecting frequency doubling voltage.
In the overall system control block diagram shown in FIG. 2, T is shown in the upper dashed boxdq/abcThe module is a dq inverse transformation module; i.e. id_refAnd iq_refRespectively generating a differential mode voltage reference value e through dq inverse transformation for dq axis current reference valuesj_ref；I2And
Figure BDA0003306567570000083
representing the magnitude and phase of the double frequency circulating current; i is3And
Figure BDA0003306567570000084
representing the amplitude and phase, U, of the frequency-tripled voltage3j_refRepresenting a frequency tripled voltage modulated signal. The lower dotted line frame shows the working process of the reference signal generator and the double frequency circulation injection controller, wherein the PI module is a proportional integral link; l isarmIs the bridge arm reactance value; t isabc/dqThe module is a dq transformation module; i.e. icira、icirb、icircRespectively measuring the a phase, the b phase and the c phase double frequency circulation; i.e. i2fdAnd i2fqD-axis double frequency circulation current and q-axis double frequency circulation current i2fd_refAnd i2fq_refIs a corresponding reference value; u. ofcird_refAnd ucirq_refD-axis double-frequency circulating current modulation voltage and q-axis double-frequency circulating current modulation voltage are respectively generated into a double-frequency circulating current modulation voltage signal U through dq inverse transformationcirj_ref。
Through the above description of the embodiments, it is clear to those skilled in the art that the above embodiments can be implemented by software, and can also be implemented by software plus a necessary general hardware platform. With this understanding, the technical solutions of the embodiments can be embodied in the form of a software product, which can be stored in a non-volatile storage medium (which can be a CD-ROM, a usb disk, a removable hard disk, etc.), and includes several instructions for enabling a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods according to the embodiments of the present invention.

Claims (6)

1. A coupling harmonic injection method for inhibiting voltage fluctuation of a half-bridge MMC capacitor is characterized by comprising the following steps of:
step 1: obtaining an expression of instantaneous power of a bridge arm containing second harmonic voltage after injection of double-frequency circulating current is considered, and establishing an optimized objective function on the basis of fundamental frequency and double-frequency fluctuation components of the instantaneous power of the bridge arm;
step 2: determining the amplitude and phase of the double frequency circulating current and the triple frequency voltage injection according to the optimization result;
and step 3: and generating a reference signal required by the controller according to the calculated amplitude and phase.
2. The method of claim 1, wherein in step 1, when obtaining the bridge arm instantaneous power expression containing the second harmonic voltage after considering double frequency circulating current injection, the method comprises the following steps:
1) obtaining a bridge arm current expression considering second harmonic current injection;
2) obtaining a bridge arm voltage expression considering third harmonic voltage injection and second harmonic voltage;
3) and obtaining the instantaneous power of the bridge arm.
3. The method of claim 2,
the leg current considering the second harmonic current injection can be expressed as:
Figure FDA0003306567560000011
wherein iau、ialRespectively an A-phase upper bridge arm current and a lower bridge arm current; omega is the fundamental angular frequency;
Figure FDA0003306567560000016
respectively a power factor angle and a second harmonic current phase angle; i is2Is the second harmonic current amplitude;
the bridge arm voltage considering the third harmonic voltage injection and the second harmonic voltage can be expressed as:
Figure FDA0003306567560000012
Figure FDA0003306567560000013
wherein U is3、
Figure FDA0003306567560000014
Respectively the amplitude and phase of the injected third harmonic voltage; i.e. icirIs the second harmonic current component;
defining the modulation ratio m as 2Um/UdcAccording to the conservation of the AC side power and the DC side power, I can be obtainedmAnd IdcThe following relationship is satisfied:
Figure FDA0003306567560000015
according to the definition of the above expression and the modulation ratio, the voltage and current expressions of the bridge arm can be simplified and expressed as follows:
Figure FDA0003306567560000021
wherein k is2And k3Respectively, the second harmonic injection coefficient and the third harmonic injection coefficient, c is a constant and has an expression of
Figure FDA0003306567560000022
From the above formula, the upper bridge arm instantaneous power PauCan be expressed as:
Figure FDA0003306567560000023
the specific expression of each secondary component in the above formula is as follows:
Figure FDA0003306567560000024
constant c is derived from the DC power PdcAnd a DC voltage UdcAnd (6) determining.
4. A method according to one of claims 1 to 3, characterized in that: in the step 1, the fundamental frequency and the double-frequency fluctuation component of the instantaneous power of the bridge arm are used as the inhibition target, and when an optimization target function is established, for the phase A, the fundamental frequency and the double-frequency fluctuation of the instantaneous power of the bridge arm on the phase A are obtained according to the instantaneous power of the bridge arm on the phase A containing double-frequency circulation injection, so that the fluctuation amplitude is obtained;
establishing an objective function according to the obtained fundamental frequency of the instantaneous power of the A-phase bridge arm and the fluctuation amplitude of the double frequency fluctuation as follows:
Figure FDA0003306567560000025
wherein, | Pau_1I and I Pau_2I is the fundamental frequency of the instantaneous power of the bridge arm on the phase A and the fluctuation amplitude of the double frequency fluctuation respectively; k represents a weight coefficient of the secondary fluctuation of the capacitor voltage.
5. The method of claim 3, wherein: the fundamental frequency and double frequency fluctuation of the instantaneous power of the bridge arm on the A phase are as follows:
Figure FDA0003306567560000031
wherein, Pau_1And Pau_2Fundamental frequency and double frequency fluctuation of instantaneous power of an upper bridge arm of the phase A are respectively obtained;
to Pau_1And Pau_2Performing an identity transform to obtain:
Figure FDA0003306567560000032
Figure FDA0003306567560000033
obtaining P according to the identity transformation resultau_1And Pau_2The fluctuation amplitude is:
Figure FDA0003306567560000034
6. the method of claim 1, wherein: generating a reference signal according to the amplitude and the phase of the injection of the double frequency circulation and the triple frequency voltage, and realizing the coupling injection of the double frequency circulation and the triple frequency voltage by combining a modulation algorithm comprises the following steps: amplitude phase k based on double frequency circulating current injection2、
Figure FDA0003306567560000035
And generating a reference signal in conjunction with a reference signal generator;
the reference signal is injected into the controller through the double frequency circulation to obtain a double frequency circulation modulation voltage signal Ucirj_ref(ii) a Using the obtained k3、
Figure FDA0003306567560000036
Optimal value is taken, and a frequency tripling voltage modulation signal U is obtained through a frequency tripling voltage injection controller3j_refFinally, the double frequency circulation and triple frequency voltage are realized by changing the modulation wave of the modulation algorithmIs injected.
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CN114726188A (en) * 2022-05-12 2022-07-08 山东大学 Constant-capacitance voltage ripple control method of modular multilevel topology wind power converter
CN114865896A (en) * 2022-01-25 2022-08-05 上海交通大学 High-voltage direct-hanging energy storage method and system for eliminating battery charging and discharging frequency doubling current
CN115224962A (en) * 2022-08-10 2022-10-21 上海交通大学 Method and system for reducing loss of submodule capacitor of cascade energy storage converter

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20150288287A1 (en) * 2012-09-21 2015-10-08 Aukland Uniservices Limited Modular multi-level converters
CN110048582A (en) * 2019-05-23 2019-07-23 华北电力大学 A kind of MMC submodule capacitor voltage fluctuation suppressing method of Harmonic coupling injection
CN112865505A (en) * 2021-02-03 2021-05-28 华北电力大学 Double-frequency circulating current injection method for inhibiting MMC bridge arm power fluctuation under fault

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20150288287A1 (en) * 2012-09-21 2015-10-08 Aukland Uniservices Limited Modular multi-level converters
CN110048582A (en) * 2019-05-23 2019-07-23 华北电力大学 A kind of MMC submodule capacitor voltage fluctuation suppressing method of Harmonic coupling injection
CN112865505A (en) * 2021-02-03 2021-05-28 华北电力大学 Double-frequency circulating current injection method for inhibiting MMC bridge arm power fluctuation under fault

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
白雪 等: "特定次谐波注入抑制模块化多电平换流器电容电压波动", 《电网与清洁能源》, no. 09 *
苑宾 等: "三次谐波注入对MMC运行特性的影响", 《高电压技术》, no. 03 *
邓伟成 等: "混合MMC子模块电容电压波动耦合抑制策略", 《华北电力大学学报(自然科学版)》, no. 05 *

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114865896A (en) * 2022-01-25 2022-08-05 上海交通大学 High-voltage direct-hanging energy storage method and system for eliminating battery charging and discharging frequency doubling current
CN114726188A (en) * 2022-05-12 2022-07-08 山东大学 Constant-capacitance voltage ripple control method of modular multilevel topology wind power converter
CN115224962A (en) * 2022-08-10 2022-10-21 上海交通大学 Method and system for reducing loss of submodule capacitor of cascade energy storage converter

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