CN112865104A - AC-DC side harmonic calculation method for power grid commutation converter - Google Patents

AC-DC side harmonic calculation method for power grid commutation converter Download PDF

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CN112865104A
CN112865104A CN202011638944.3A CN202011638944A CN112865104A CN 112865104 A CN112865104 A CN 112865104A CN 202011638944 A CN202011638944 A CN 202011638944A CN 112865104 A CN112865104 A CN 112865104A
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harmonic
phase
switching function
converter
current
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王顺亮
陈代忠
焦宁
孟锦豪
刘天琪
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Sichuan University
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Sichuan University
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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
    • H02J3/01—Arrangements for reducing harmonics or ripples
    • 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
    • H02J1/00—Circuit arrangements for dc mains or dc distribution networks
    • H02J1/02—Arrangements for reducing harmonics or ripples
    • 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
    • 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
    • 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
    • H02J2203/00—Indexing scheme relating to details of circuit arrangements for AC mains or AC distribution networks
    • H02J2203/20—Simulating, e g planning, reliability check, modelling or computer assisted design [CAD]
    • 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
    • Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
    • Y02E40/40—Arrangements for reducing harmonics
    • 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

The invention discloses a power grid commutation converter AC-DC side harmonic calculation method based on an improved unified switching function, which adopts a dynamic vector method to divide a continuous time domain signal waveform into multi-order dynamic vectors; constructing an improved unified switching function of the power grid commutation converter according to the mutual relation of voltage and current on the alternating current side and the direct current side of the power grid commutation converter; and calculating an improved unified switching function dynamic phasor matrix according to the multi-order dynamic vectors and the improved unified switching function, and calculating the amplitude and phase information of each harmonic wave by combining the corresponding relation between the dynamic phasor and the harmonic wave. The method can calculate the amplitude of the harmonic wave and the phase of the harmonic wave, simplifies the calculation process, improves the calculation precision and provides reference for harmonic wave instability analysis of the LCC.

Description

AC-DC side harmonic calculation method for power grid commutation converter
Technical Field
The invention relates to the technical field of converter harmonic coupling, in particular to a method for calculating harmonic waves on an alternating current side and a direct current side of a power grid commutation converter.
Background
The Line Communated Converter (LCC) has the characteristics of mature application, relatively low cost and the like. In recent years, it has gained more and more attention in the field of High Voltage Direct Current (HVDC). However, due to the non-linear characteristic of the inverter device, harmonic waves are generated in the alternating current and direct current system, and the harmonic waves even affect the stability of the system. Therefore, the harmonic transformation rule of the AC side and the DC side of the LCC is analyzed, and the method has very important significance for researching the harmonic instability of the LCC-HVDC.
At present, the modeling of the LCC at home and abroad mainly comprises a quasi-steady-state model, a switching function model, a real object switching model, a three-pulse wave model and the like. The switching function model is widely concerned because the physical concept is clear and the relation of harmonic wave transmission at two sides of the converter can be better reflected, but the switching function model also has the defect of insufficient precision. Therefore, how to improve the accuracy of the LCC switching function to study its harmonic transfer law still needs further research.
Disclosure of Invention
Aiming at the defects in the prior art, the invention provides a power grid commutation converter AC/DC side harmonic calculation method.
In order to achieve the purpose of the invention, the invention adopts the technical scheme that:
a power grid commutation converter AC/DC side harmonic calculation method comprises the following steps:
s1, dividing the continuous time domain signal waveform into multi-order dynamic vectors by adopting a dynamic vector method;
s2, constructing an improved unified switching function of the power grid commutation converter according to the mutual relation of voltage and current on the alternating current side and the direct current side of the power grid commutation converter;
and S3, calculating an improved unified switching function dynamic phasor matrix according to the multi-order dynamic vectors in the step S1 and the improved unified switching function in the step S2, and calculating the amplitude and phase information of each subharmonic by combining the corresponding relation between the dynamic phasor and the harmonic.
The beneficial effect of this scheme is: the invention provides the LCC harmonic transformation quantitative analysis and calculation method by improving the uniform voltage and current switching function and then using matrix operation based on the dynamic phasor, the method not only can calculate the amplitude of the harmonic, but also can calculate the phase of the harmonic, meanwhile, the calculation process is simplified, the calculation precision is improved, and reference is provided for the harmonic instability analysis of the LCC.
Further, the step S1 specifically includes:
setting continuous time domain signal waveform as x (T), equally dividing the time domain signal waveform into a plurality of equal division intervals with the length of T, and expanding the time domain signal waveform into Fourier series in any interval T epsilon (tau-T, tau) to be expressed as:
Figure BDA0002879406710000021
wherein, Xn(τ) is the n-th Fourier coefficient, ω02 pi/T is the fundamental frequency;
fourier coefficient Xn(τ) is expressed as n-order dynamic phasor:
Figure BDA0002879406710000022
the beneficial effects of the further scheme are as follows: the time domain signal can be expanded in the frequency domain, and more accurate harmonic calculation is conveniently realized.
Further, the step S2 specifically includes:
according to the mathematical model of the power grid commutation converter, the mutual relation of the voltage and current switching functions of the power grid commutation converter is obtained as follows:
Figure BDA0002879406710000031
wherein S isua、SubSwitching function of the phase voltage of a and b, Sia、SibSwitching functions of phase a and phase b currents respectively;
for a 6-pulse power grid commutation converter of YY wiring, an improved unified switching function in a period is constructed and expressed as:
Figure BDA0002879406710000032
wherein S isaAnd the improved unified switching function of the phase a is shown, alpha is a delay trigger angle, and mu is a commutation angle.
The beneficial effects of the further scheme are as follows: the unified switching function can reduce the amount of switching function computation by half.
Further, in the step S2, for the YD-wired 6-pulse grid commutated converter, an improved unified switching function in one period is constructed, which is expressed as:
Figure BDA0002879406710000041
wherein S isaAnd the improved unified switching function of the phase a is shown, alpha is a delay trigger angle, and mu is a commutation angle.
The beneficial effects of the further scheme are as follows: the unified switching function can reduce the amount of switching function computation by half.
Further, in step S2, for the 12-ripple grid commutation converter, a relationship between the grid-side current and the dc-side voltage is constructed as follows:
Figure BDA0002879406710000042
wherein iφYY、iφYD、iφ12PThe grid side current of the YY wiring power grid commutation converter, the grid side current of the YD wiring power grid commutation converter and the current of the 12-pulse power grid commutation converter are respectively; u. ofdYY、udYD、udThe direct-current side voltage of the YY wiring power grid commutation converter, the direct-current side voltage of the YD wiring power grid commutation converter and the total direct-current side voltage of the 12-pulse power grid commutation converter are respectively.
The beneficial effects of the further scheme are as follows: the amount of calculation can be reduced.
Further, the step S3 specifically includes:
calculating an improved unified switching function dynamic phasor matrix according to the multi-order dynamic vectors in the step S1 and the improved unified switching function in the step S2;
setting the relation between a direct current source and a harmonic source on the direct current side, and calculating a phi alternating current dynamic phasor matrix;
setting the relation between three-phase alternating fundamental voltage and an alternating three-phase harmonic voltage source, and calculating a direct-current side voltage dynamic phasor matrix;
and calculating the amplitude and phase information of each harmonic according to the corresponding relation between the dynamic phasor and the harmonic.
The beneficial effects of the further scheme are as follows: the amount of calculation can be reduced.
Further, the unified switching function dynamic phasor matrix S is improved in the step S3φExpressed as:
Figure BDA0002879406710000051
wherein phi is a, b, c is each phase, Sφ(n)Is the amplitude of the dynamic phasor of the nth switching function, thetasφ(n)The phase of the dynamic phasor for the nth switching function.
Further, the phi ac current dynamic phasor matrix I in the step S3φExpressed as:
Figure BDA0002879406710000061
wherein, Iφ(n)Is the amplitude of the current dynamic phasor at the nth time, thetaiφ(n)Is the phase of the current dynamic phasor for the nth time.
Further, in the step S3, the dc side voltage dynamic phasor matrix UdIs shown as
Figure BDA0002879406710000062
Wherein, Ud(n)Is the amplitude of the nth voltage dynamic phasor, θud(n)Is the phase of the nth voltage dynamic phasor.
The beneficial effects of the further scheme are as follows: and the time domain signals are expanded into frequency domain quantity, and the frequency domain quantity adopts matrix operation, so that coupling calculation among harmonic waves is facilitated.
Further, the calculation formula for calculating the amplitude and phase information of each harmonic in step S3 is represented as:
Figure BDA0002879406710000071
wherein, UnFor the amplitude of the n-th harmonic,
Figure BDA0002879406710000072
for n-th harmonic phase, < u >n、〈u〉-nRespectively n-order and n-order voltage dynamic phasors.
The beneficial effects of the further scheme are as follows: the dynamic phasor, harmonic amplitude and phase information can be directly corresponded.
Drawings
FIG. 1 is a schematic flow chart of a method for calculating AC/DC side harmonic waves of a power grid commutation converter according to the present invention;
FIG. 2 is a schematic diagram of a topology structure of a power grid commutation converter in the embodiment of the invention;
FIG. 3 is a comparison graph of a-phase harmonic currents on the AC side after injecting 1% 3-order harmonic currents on the DC side in the embodiment of the present invention;
fig. 4 is a comparison graph of harmonic voltage at the dc side after injecting 1% asymmetric 10 th harmonic voltage at the ac side in the embodiment of the present invention.
Detailed Description
The following description of the embodiments of the present invention is provided to facilitate the understanding of the present invention by those skilled in the art, but it should be understood that the present invention is not limited to the scope of the embodiments, and it will be apparent to those skilled in the art that various changes may be made without departing from the spirit and scope of the invention as defined and defined in the appended claims, and all matters produced by the invention using the inventive concept are protected.
As shown in fig. 1, an embodiment of the present invention provides a method for calculating ac-dc side harmonics of a grid commutation converter, including the following steps S1 to S3:
s1, dividing the continuous time domain signal waveform into multi-order dynamic vectors by adopting a dynamic vector method;
in this embodiment, step S1 specifically includes:
setting continuous time domain signal waveform as x (T), equally dividing the time domain signal waveform into a plurality of equal division intervals with the length of T, and expanding the time domain signal waveform into Fourier series in any interval T epsilon (tau-T, tau) to be expressed as:
Figure BDA0002879406710000081
wherein, Xn(τ) is the n-th Fourier coefficient, ω02 pi/T is the fundamental frequency;
fourier coefficient Xn(τ) is expressed as n-order dynamic phasor:
Figure BDA0002879406710000082
n-order dynamic phasor (x)n(τ) is a variable related to time τ, which varies as time τ, corresponding to the time in the sliding interval (τ -T, τ)]Subjecting the signal x (t) to a time-varying Fourier transform, < x >n(τ) will also vary with τ.
The dynamic phasor has the following properties: assuming that there are three time domain signals p (t), u (t), i (t), and that p (t) u (t) i (t) is satisfied, there are:
Figure BDA0002879406710000083
s2, constructing an improved unified switching function of the power grid commutation converter according to the mutual relation of voltage and current on the alternating current side and the direct current side of the power grid commutation converter;
in this embodiment, step S2 specifically includes:
and obtaining the mutual relation of the voltage and the current at the AC side and the DC side of the power grid commutation converter according to the mathematical model of the power grid commutation converter. In the phase change process, taking the voltage switching function of two phases a and b as an example, the proportion of the equivalent voltage transferred from the alternating voltage to the direct current side is set as follows:
Figure BDA0002879406710000091
wherein S isua、SubSwitching function of the phase voltage of a and b, Sia、SibSwitching functions of phase a and phase b currents respectively; s in the phase change processia+Sib1. The above equation indicates that the voltage switching function is the same as the current switching function during commutation; during the non-phase-change period, the three-phase voltage and current switching functions are the same; therefore, the three-phase voltage and the current switching function are the same at any time, and accordingly, an improved and unified 6-pulse current converter switching function S can be establishedφ＝Suφ＝Siφ(where φ ═ a, b, c).
When the LCC converter transformer BUS voltage reference phase is as follows:
Figure BDA0002879406710000092
for a 6-pulse power grid commutation converter of YY wiring, taking a phase as an example, an improved unified switching function in a period is constructed and expressed as:
Figure BDA0002879406710000093
wherein S isaAnd the improved unified switching function of the phase a is shown, alpha is a delay trigger angle, and mu is a commutation angle. b. The c-phase switching function lags and leads the a-phase switching function by 120 deg., respectively.
For a 6-pulse power grid commutation converter with YD wiring, taking a phase as an example, an improved unified switching function in a period is constructed and expressed as:
Figure BDA0002879406710000101
wherein S isaAnd the improved unified switching function of the phase a is shown, alpha is a delay trigger angle, and mu is a commutation angle. b. The c-phase switching function lags and leads the a-phase switching function by 120 deg., respectively.
For a 12-pulse power grid commutation converter, 2 groups of 6-pulse converters with different wiring commutation converters are connected in parallel at an alternating current side and connected in series at a direct current side, and the relationship between the current at the grid side and the voltage at the direct current side is established as follows:
Figure BDA0002879406710000102
wherein iφYY、iφYD、iφ12PThe grid side current of the YY wiring power grid commutation converter, the grid side current of the YD wiring power grid commutation converter and the current of the 12-pulse power grid commutation converter are respectively; u. ofdYY、udYD、udThe direct-current side voltage of the YY wiring power grid commutation converter, the direct-current side voltage of the YD wiring power grid commutation converter and the total direct-current side voltage of the 12-pulse power grid commutation converter are respectively.
And S3, calculating an improved unified switching function dynamic phasor matrix according to the multi-order dynamic vectors in the step S1 and the improved unified switching function in the step S2, and calculating the amplitude and phase information of each subharmonic by combining the corresponding relation between the dynamic phasor and the harmonic.
In this embodiment, step S3 specifically includes:
calculating an improved unified switching function dynamic phasor matrix S based on the multi-level dynamic vectors in step S1 and the improved unified switching function in step S2φ。
Take as an example that all harmonics within the 31 th order range are considered. For LCC of different wiring converter changes, the improved unified switching function of the 6-pulse power grid converter with YY or YD wiring is substituted into n-order dynamic phasor (x)n(tau) calculating the dynamic phasors of each order of the improved unified switching function from-31 to 31 for n, and obtaining 3 dynamic phasor matrixes S of the improved unified switching function of 63 multiplied by 1 ordersφ(Φ ═ a, b, c) is represented by:
Figure BDA0002879406710000111
where the elements in the matrix are known complex numbers found, phi a, b, c are phases, Sφ(n)Is the amplitude, θsφ(n)Is the phase;
assigning the elements in the above formula to the transfer matrix
Figure BDA0002879406710000112
(63 × 63 th order,. phi.: a, b, c) as shown
Figure BDA0002879406710000121
Setting the DC side to have a DC source Id0Harmonic source ihIn a relationship of
Figure BDA0002879406710000122
Wherein, IhIs the amplitude of the harmonic source, thetaidhIs the phase of the harmonic source;
thereby determining a DC current dynamic phasor matrix Id(order 63 × 1) is:
Figure BDA0002879406710000123
dynamic phasor matrix I for direct currentdAdding a current transfer mode:
Figure BDA0002879406710000124
obtaining phi alternating current dynamic phasor matrix Iφ(order 63X 1) is
Figure BDA0002879406710000131
Wherein the elements in the matrix are known complex numbers, Iφ(n)Is the amplitude, θiφ(n)Is the phase;
setting a three-phase AC fundamental voltage ugφ1(amplitude U)gφ1Phase thetaugφ1) And AC three-phase harmonic voltage source uhφIn a relationship of
Figure BDA0002879406710000132
Wherein, Uhφ、θuhφThe amplitude and the phase of the harmonic voltage source are respectively;
thereby determining an AC side phi phase voltage dynamic phasor matrix Uφ(order 63X 1) is
Figure BDA0002879406710000133
Dynamic phasor matrix U of phi-phase voltage on alternating current sideφSubstituting a voltage transfer equation:
Figure BDA0002879406710000141
obtaining a DC side voltage dynamic phasor matrix Ud(order 63X 1) is
Figure BDA0002879406710000142
Wherein the elements in the matrix are known complex numbers, U, obtainedd(n)Is the amplitude, θud(n)Is the phase;
calculating the amplitude and phase information of each harmonic according to the corresponding relation between the dynamic phasor and the harmonic, and expressing as follows:
Figure BDA0002879406710000143
wherein, UnFor the amplitude of the n-th harmonic,
Figure BDA0002879406710000144
for n-th harmonic phase, < u >n、〈u>-nRespectively n-order and n-order voltage dynamic phasors. The DC side voltage dynamic phasor matrix UdThe dynamic phasors in the above equation are substituted into the above equation to obtain the specific amplitude and phase information of each harmonic.
In the following, the present invention takes a two-terminal LCC-HVDC system as an example for simulation, as shown in FIG. 2, which is a schematic diagram of a topology structure of LCC, wherein uφ、iφ(a, b, c) represents the phase voltage and current on the ac side, u represents the phase voltage and current on the ac side, respectivelyd、idRespectively representing the voltage and current on the DC side, ZdRepresenting the dc side impedance. According to the invention, harmonic current with the content of 1% and the frequency of 150Hz is added on the direct current side, and current fluctuation of 100Hz and 200Hz is generated on the alternating current side according to the analysis. The addition of 1% asymmetric voltage harmonics at a frequency of 500Hz on the AC side, as can be seen from the above analysis, will produce harmonic voltages of 450Hz and 550Hz in the DC side voltage. And (4) building LCC-HVDC two-end models on a PSCAD simulation platform, and recording experimental data and comparing the experimental data with a calculation result.
The simulation test compares the amplitude and the phase of the harmonic content after the harmonic is added to verify the correctness of the harmonic transformation rule analyzed above. In addition, in order to prove that the method of the invention improves the precision, the calculation result of the traditional switch function calculation method is added into the simulation comparison data. The two methods are respectively as follows:
1) the method comprises the following steps: the method provided by the invention;
2) the method 2 comprises the following steps: conventional switching function calculation methods.
The correctness of the analysis result of the relationship between the harmonic variation on the DC side and the AC side can be proved by comparing the harmonic contents of 100Hz and 200Hz in the AC side current in FIG. 3(a) and the harmonic phases of 100Hz and 200Hz in the AC side current in FIG. 3 (b). Through the comparison of harmonic voltage contents of 450Hz and 550Hz on the DC side in FIG. 4(a) and the comparison of harmonic voltage phases of 450Hz and 550Hz on the DC side in FIG. 4(b), the correctness of the analysis result of the relationship between the harmonic variation on the AC side and the harmonic variation on the DC side can be proved.
The present invention is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
The principle and the implementation mode of the invention are explained by applying specific embodiments in the invention, and the description of the embodiments is only used for helping to understand the method and the core idea of the invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, there may be variations in the specific embodiments and the application scope, and in summary, the content of the present specification should not be construed as a limitation to the present invention.
It will be appreciated by those of ordinary skill in the art that the embodiments described herein are intended to assist the reader in understanding the principles of the invention and are to be construed as being without limitation to such specifically recited embodiments and examples. Those skilled in the art can make various other specific changes and combinations based on the teachings of the present invention without departing from the spirit of the invention, and these changes and combinations are within the scope of the invention.

Claims (10)

1. A power grid commutation converter AC/DC side harmonic calculation method is characterized by comprising the following steps:
s1, dividing the continuous time domain signal waveform into multi-order dynamic vectors by adopting a dynamic vector method;
s2, constructing an improved unified switching function of the power grid commutation converter according to the mutual relation of voltage and current on the alternating current side and the direct current side of the power grid commutation converter;
and S3, calculating an improved unified switching function dynamic phasor matrix according to the multi-order dynamic vectors in the step S1 and the improved unified switching function in the step S2, and calculating the amplitude and phase information of each subharmonic by combining the corresponding relation between the dynamic phasor and the harmonic.
2. The grid commutated converter ac/dc side harmonic calculation method according to claim 1, wherein the step S1 specifically comprises:
setting continuous time domain signal waveform as x (T), equally dividing the time domain signal waveform into a plurality of equal division intervals with the length of T, and expanding the time domain signal waveform into Fourier series in any interval T epsilon (tau-T, tau) to be expressed as:
Figure FDA0002879406700000011
wherein, Xn(τ) is the n-th Fourier coefficient, ω02 pi/T is the fundamental frequency;
fourier coefficient Xn(τ) is expressed as n-order dynamic phasor:
Figure FDA0002879406700000012
3. the grid commutated converter ac/dc side harmonic calculation method according to claim 2, wherein the step S2 specifically comprises:
according to the mathematical model of the power grid commutation converter, the mutual relation of the voltage and current switching functions of the power grid commutation converter is obtained as follows:
Figure FDA0002879406700000021
wherein S isua、SubSwitching function of the phase voltage of a and b, Sia、SibSwitching functions of phase a and phase b currents respectively;
for a 6-pulse power grid commutation converter of YY wiring, an improved unified switching function in a period is constructed and expressed as:
Figure FDA0002879406700000022
wherein S isaAnd the improved unified switching function of the phase a is shown, alpha is a delay trigger angle, and mu is a commutation angle.
4. The grid commutated converter ac/dc side harmonic calculation method according to claim 3, wherein the improved uniform switching function in one period of the 6-pulse grid commutated converter with YD connections in step S2 is constructed as follows:
Figure FDA0002879406700000031
wherein S isaAnd the improved unified switching function of the phase a is shown, alpha is a delay trigger angle, and mu is a commutation angle.
5. The grid commutated converter ac/dc-side harmonic calculation method according to claim 4, wherein in step S2, for the 12-ripple grid commutated converter, a grid-side current and dc-side voltage relationship is constructed as follows:
Figure FDA0002879406700000032
wherein iφYY、iφYD、iφ12PThe grid side current of the YY wiring power grid commutation converter, the grid side current of the YD wiring power grid commutation converter and the current of the 12-pulse power grid commutation converter are respectively; u. ofdYY、udYD、udThe direct-current side voltage of the YY wiring power grid commutation converter, the direct-current side voltage of the YD wiring power grid commutation converter and the total direct-current side voltage of the 12-pulse power grid commutation converter are respectively.
6. The grid commutated converter ac/dc side harmonic calculation method according to claim 5, wherein the step S3 specifically comprises:
calculating an improved unified switching function dynamic phasor matrix according to the multi-order dynamic vectors in the step S1 and the improved unified switching function in the step S2;
setting the relation between a direct current source and a harmonic source on the direct current side, and calculating a phi alternating current dynamic phasor matrix;
setting the relation between three-phase alternating fundamental voltage and an alternating three-phase harmonic voltage source, and calculating a direct-current side voltage dynamic phasor matrix;
and calculating the amplitude and phase information of each harmonic according to the corresponding relation between the dynamic phasor and the harmonic.
7. The AC-DC side harmonic calculation method for the grid commutated converter according to claim 6, wherein the step S3 is to improve a unified switching function dynamic phasor matrix SφExpressed as:
Figure FDA0002879406700000041
wherein phi is a, b, c is each phase, Sφ(n)Is the amplitude of the dynamic phasor of the nth switching function, thetasφ(n)The phase of the dynamic phasor for the nth switching function.
8. The AC-DC side harmonic calculation method for the grid commutated converter according to claim 7, wherein the phi AC current dynamic phasor matrix I in the step S3φExpressed as:
Figure FDA0002879406700000042
wherein, Iφ(n)Is the amplitude of the current dynamic phasor at the nth time, thetaiφ(n)Is the phase of the current dynamic phasor for the nth time.
9. The method according to claim 8, wherein the dc-side voltage dynamic phasor matrix U in step S3 is used for calculating the ac-dc-side harmonic of the ac-dc converterdIs shown as
Figure FDA0002879406700000051
Wherein, Ud(n)Is the amplitude of the nth voltage dynamic phasor, θud(n)Is the phase of the nth voltage dynamic phasor.
10. The grid commutation converter ac-dc side harmonic calculation method according to claim 9, wherein the calculation formula for calculating the amplitude and phase information of each harmonic in step S3 is represented as:
Figure FDA0002879406700000052
wherein, UnFor the amplitude of the n-th harmonic,
Figure FDA0002879406700000053
for the phase of the n-th harmonic,<u〉n、〈u〉-nrespectively n-order and n-order voltage dynamic phasors.
CN202011638944.3A 2020-12-31 2020-12-31 AC-DC side harmonic calculation method for power grid commutation converter Pending CN112865104A (en)

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