CN112018773B - Control method and device for low-order harmonic oscillation of direct current station and storage medium - Google Patents
Control method and device for low-order harmonic oscillation of direct current station and storage medium Download PDFInfo
- Publication number
- CN112018773B CN112018773B CN202010901446.7A CN202010901446A CN112018773B CN 112018773 B CN112018773 B CN 112018773B CN 202010901446 A CN202010901446 A CN 202010901446A CN 112018773 B CN112018773 B CN 112018773B
- Authority
- CN
- China
- Prior art keywords
- harmonic
- low
- phase
- statcom
- direct current
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
- 230000010355 oscillation Effects 0.000 title claims abstract description 55
- 238000000034 method Methods 0.000 title claims abstract description 46
- 238000004590 computer program Methods 0.000 claims description 25
- 238000001914 filtration Methods 0.000 claims description 7
- 238000012938 design process Methods 0.000 claims description 4
- 230000004913 activation Effects 0.000 claims 1
- 230000009849 deactivation Effects 0.000 claims 1
- 238000010586 diagram Methods 0.000 description 20
- 230000005540 biological transmission Effects 0.000 description 10
- 230000006870 function Effects 0.000 description 8
- 230000006872 improvement Effects 0.000 description 3
- 230000002401 inhibitory effect Effects 0.000 description 3
- 230000001052 transient effect Effects 0.000 description 3
- 230000003993 interaction Effects 0.000 description 2
- 238000004088 simulation Methods 0.000 description 2
- 230000003068 static effect Effects 0.000 description 2
- 230000001360 synchronised effect Effects 0.000 description 2
- 230000003321 amplification Effects 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 230000002238 attenuated effect Effects 0.000 description 1
- 230000001413 cellular effect Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000013016 damping Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000004134 energy conservation Methods 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000003199 nucleic acid amplification method Methods 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 238000005070 sampling Methods 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 230000001629 suppression Effects 0.000 description 1
Images
Classifications
-
- 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
- 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
-
- 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
- Y02E40/10—Flexible AC transmission systems [FACTS]
-
- 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]
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Inverter Devices (AREA)
Abstract
The invention discloses a control method, a device and a storage medium for low-order harmonic oscillation of a direct current station, wherein the method comprises the following steps: acquiring a bus voltage waveform of the direct current converter station, and determining the frequency of low-order harmonic contained in the waveform; adding an additional control branch with corresponding frequency; acquiring three-phase instantaneous line voltage and instantaneous current at an MMC-STATCOM grid-connected port; in the added additional control branch, the instantaneous line voltage respectively passes through a band-pass filter and the gain link to obtain a corresponding harmonic current instruction; making a difference between the harmonic current instruction and the instantaneous current, and enabling the difference value to pass through a resonance controller to obtain a corresponding harmonic voltage instruction; adding the harmonic voltage commands of all the added control branches to obtain a total harmonic voltage command; and adding the total harmonic voltage instruction to an output value of a primary current controller in the MMC-STATCOM so as to inhibit low-order harmonic oscillation of the direct current converter station. The invention can inhibit the low-order harmonic oscillation of the direct current converter station, so that the direct current converter station can run more stably and safely.
Description
Technical Field
The invention relates to the technical field of power system stability control, in particular to a control method and device for low-order harmonic oscillation of a direct current station and a storage medium.
Background
The high-voltage direct-current transmission has the advantages of energy conservation, low line cost and the like, plays an important role in long-distance and high-power transmission, and is widely applied to power grids of various countries. A converter station of a hvdc transmission system may be understood as a modulator with voltage and current conversion, where there is a dynamic harmonic interaction between the ac and dc networks through the converter station. This interaction may cause harmonic cross modulation, harmonic amplification, harmonic resonance, or harmonic instability. When harmonic instability occurs, harmonic current is amplified by several times or even dozens of times, and the caused voltage distortion can cause difficult operation of the high-voltage direct-current transmission system and even system locking.
At present, methods for suppressing low-order harmonic instability of a high-voltage direct-current power transmission system mainly include two types of installation of a non-characteristic harmonic filter and addition of a harmonic damping circuit in a direct-current control system. For a part of direct current converter stations which are already provided with Static Synchronous compensators (STATCOMs) with certain capacity, the STATCOMs based on Insulated Gate Bipolar Transistor (IGBT) devices are flexible to control, the output current characteristics of the STATCOMs can be rapidly adjusted according to different control targets, and therefore the control potential for inhibiting the instability of low-order harmonics of different frequencies of the direct current converter stations is achieved. However,. At present, a high-voltage direct-current power transmission system provided with a STATCOM has no control measure for inhibiting low-order harmonic instability of the high-voltage direct-current power transmission system based on the STATCOM.
Disclosure of Invention
The embodiment of the invention aims to provide a control method, a control device and a storage medium for low-order harmonic oscillation of a direct current station.
In order to achieve the above object, an embodiment of the present invention provides a method for controlling low-order harmonic oscillation of a dc power station, including the following steps:
acquiring a bus voltage waveform of a direct current converter station, and determining the frequency of low-order harmonic contained in the waveform according to the bus voltage waveform;
determining an additional control branch corresponding to the frequency according to the determined frequency of the low-order harmonic; the additional control branch is added to an original current controller in an MMC-STATCOM of the direct current converter station and comprises a band-pass filter, a gain link and a resonance controller;
acquiring three-phase instantaneous line voltage at the MMC-STATCOM grid-connected port and instantaneous current of a corresponding three-phase bridge arm;
in any one of the added control branches, the instantaneous line voltage of each phase passes through the band-pass filter and the gain link respectively to obtain each corresponding harmonic current instruction;
making a difference between the harmonic current instruction of each phase and the instantaneous current of the bridge arm of the phase, and enabling the difference value to pass through the resonance controller to obtain each corresponding harmonic voltage instruction;
adding the harmonic voltage commands of each phase of all the added control branches to obtain a total harmonic voltage command of the phase;
and adding the total harmonic voltage instruction to an output value of a primary current controller in the MMC-STATCOM so as to inhibit low-order harmonic oscillation of the direct current converter station.
Preferably, whether the additional control branch is put into operation or not is controlled by an identification variable, and when the identification variable is set to be at a high level, the additional control branch is put into operation; when the identification variable is set to a low level, the additional control branch is not put into operation.
Preferably, the frequency of the low harmonic is n, n is a positive integer, and n is more than or equal to 2 and less than 10.
Preferably, the band-pass filter has an expression of
Wherein, a n ，b n ，c n ，d n ，e n ，f n Respectively constant coefficients to be determined in the design process of the band-pass filter, and the design values are a n ＝(ω z -20π) 2 ，
d n ＝(ω z +20π) 2 ，
ω z ＝2×50π*n，ω z The angular frequency of the low order harmonics to be suppressed.
Another embodiment of the present invention provides a control apparatus for low harmonic oscillation of a dc power station, including:
the waveform acquisition module is used for acquiring the bus voltage waveform of the direct current converter station and determining the frequency of low-order harmonics contained in the waveform according to the bus voltage waveform;
the branch input module is used for determining to input an additional control branch corresponding to the frequency according to the determined frequency of the low-order harmonic; the additional control branch is added to an original current controller in an MMC-STATCOM of the direct current converter station and comprises a band-pass filter, a gain link and a resonance controller;
the electric quantity acquisition module is used for acquiring a three-phase instantaneous line voltage at the MMC-STATCOM grid-connected port and an instantaneous current corresponding to a three-phase bridge arm;
the filtering gain module is used for enabling the instantaneous line voltage of each phase to respectively pass through the band-pass filter and the gain link in any one added control branch circuit to obtain each corresponding harmonic current instruction;
the resonance control module is used for making a difference between the harmonic current instruction of each phase and the instantaneous current of the bridge arm of the phase, and obtaining each corresponding harmonic voltage instruction by passing the difference through the resonance controller;
the superposition module is used for adding the harmonic voltage commands of each phase of all the added control branches to obtain a total harmonic voltage command of the phase;
and the output module is used for attaching the total harmonic voltage instruction to an output value of a primary current controller in the MMC-STATCOM so as to inhibit low-order harmonic oscillation of the direct current converter station.
Another embodiment of the present invention correspondingly provides an apparatus using a control method for dc station low harmonic oscillation, including a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, where the processor executes the computer program to implement the control method for dc station low harmonic oscillation as described in any one of the above.
A further embodiment of the present invention provides a computer-readable storage medium, which includes a stored computer program, wherein when the computer program runs, an apparatus on which the computer-readable storage medium is located is controlled to execute the method for controlling low-order harmonic oscillation of a dc power station according to any one of the above items.
Compared with the prior art, the method, the device and the storage medium for controlling the low-order harmonic oscillation of the direct current converter station provided by the embodiment of the invention have the advantages that the additional control branch corresponding to the harmonics with different frequencies is additionally arranged on the original current controller to carry out filtering, gain and resonance control on the waveform of the bus voltage, so that the low-order harmonic oscillation of the direct current converter station is inhibited, and the direct current converter station is more stable and safer to operate. The invention is provided based on MMC-STATCOM, can be applied to a high-voltage direct-current transmission scene, and helps to inhibit the low-order harmonic instability phenomenon of a direct-current converter station.
Drawings
FIG. 1 is a schematic flow chart diagram illustrating an embodiment of a method for controlling low harmonic oscillation of a DC power station according to the present invention;
FIG. 2 is an additional control block diagram of one embodiment of an MMC-STATCOM provided by the present invention;
FIG. 3 is a basic control block diagram of an embodiment of the MMC-STATCOM provided by the present invention without additional control;
FIG. 4 is a schematic flow chart diagram illustrating another embodiment of a method for controlling low harmonic oscillation of a DC plant according to the present invention;
fig. 5 is a schematic structural diagram of an embodiment of a dc converter station system equipped with a STATCOM provided by the present invention;
FIG. 6 is a schematic diagram of an embodiment of a topology of an MMC-STATCOM in a delta connection mode according to the present invention;
fig. 7 is a general control logic block diagram of an embodiment of a delta connection based dc converter station provided by the present invention;
FIG. 8 is a schematic diagram showing comparison of waveforms of effective voltage values of a bus of a converter station after a short-circuit fault before and after a MMC-STATCOM low-order harmonic additional control branch circuit of the DC converter station provided by the invention is put into operation;
FIG. 9 is a schematic structural diagram of an embodiment of a control device for low harmonic oscillation of a DC power station according to the present invention;
fig. 10 is a schematic structural diagram of an embodiment of an apparatus using a control method for low-order harmonic oscillation of a dc power station according to the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Referring to fig. 1, it is a schematic flow chart of an embodiment of a method for controlling low-order harmonic oscillation of a dc power station, where the method includes steps S1 to S7:
s1, acquiring a bus voltage waveform of a direct current converter station, and determining the frequency of low-order harmonics contained in the waveform according to the bus voltage waveform;
s2, determining to input an additional control branch corresponding to the frequency according to the determined frequency of the low-order harmonic; the additional control branch is added to an original current controller in an MMC-STATCOM of the direct current converter station and comprises a band-pass filter, a gain link and a resonance controller;
s3, acquiring three-phase instantaneous line voltage at the MMC-STATCOM grid-connected port and instantaneous current corresponding to a three-phase bridge arm;
s4, in any one added control branch, enabling the instantaneous line voltage of each phase to pass through the band-pass filter and the gain link respectively to obtain each corresponding harmonic current instruction;
s5, making a difference between the harmonic current instruction of each phase and the instantaneous current of the bridge arm of the phase, and enabling the difference value to pass through the resonance controller to obtain each corresponding harmonic voltage instruction;
s6, adding the harmonic voltage commands of each phase of all the added control branches to obtain a total harmonic voltage command of the phase;
and S7, adding the total harmonic voltage instruction to an output value of a primary current controller in the MMC-STATCOM to inhibit low-order harmonic oscillation of the direct current converter station.
It should be noted that, referring to fig. 2, an additional control block diagram of an embodiment of the MMC-STATCOM provided in the present invention is shown. In fig. 2, the additional control branch includes four branches, which are a 2-order harmonic additional control branch, a 3-order harmonic additional control branch, a 4-order harmonic additional control branch, and an n-order harmonic additional control branch, respectively, where the n-order harmonic additional control branch is a schematic of a general additional control branch. The input values and the output values obtained in fig. 2 are only for the purpose of suppressing the low harmonics of the ab-phase of the dc converter station, and the values of the other phases can be derived similarly.
Specifically, bus voltage waveforms of the direct current converter station are obtained, and the frequency of low-order harmonics contained in the waveforms is determined according to the bus voltage waveforms. The bus voltage waveform of the direct current converter station can be obtained from historical operation data of the direct current converter station, or electrical parameters in actual operation are directly collected through a voltage transformer, or a corresponding model is built in a laboratory for simulation to obtain a corresponding simulation waveform. The frequency of the low order harmonics present in the waveform can be determined by Fast Fourier Transform (FFT) analysis from the bus voltage waveform.
Determining an additional control branch circuit which is input with the corresponding frequency according to the determined frequency of the low-order harmonic; the additional control branch is added to a primary current controller in an MMC-STATCOM of the direct current converter station and comprises a band-pass filter, a gain link and a resonance controller. MMC is called Modular Multilevel Converter in the whole, and Chinese is called Modular Multilevel Converter. STATCOM is known under the general name Static Synchronous Compensator, chinese. Referring to fig. 3, it is a basic control block diagram of an embodiment of the MMC-STATCOM without additional control provided in the present invention, and similarly, the input value and the output value are illustrated by using ab-phase control as an example. Wherein i abref And i ab Respectively representing current instruction value and current sampling value, PR of MMC-STATCOM instantaneous current control 50 Proportional resonant controller for fundamental current, R 150 The resonant controller is a 3-frequency doubling current resonant controller, and is mainly used for inhibiting MMC-STATCOM three-time zero-sequence circulating current in a triangular connection mode.
And acquiring three-phase instantaneous line voltage at the MMC-STATCOM grid-connected port and instantaneous current of a corresponding three-phase bridge arm. Three-phase instantaneous line voltage comprising u ab ，u bc ，u ca Instantaneous current of three-phase bridge arm includes i ab ，i bc ，i ca ；u ab ＝u A -u B ,，u bc ＝u B -u C ，u ca ＝u C -u A ，u A ，u B ，u C The phase voltages of the alternating current buses A, B and C of the direct current converter station are respectively phase voltages.
In any added control branch, the instantaneous line voltage of each phase passes through a band-pass filter and a gain link respectively to obtain each corresponding harmonic current instruction. In ab phaseAnd 2 th harmonic additional control branch as an example, u ab Pass band pass filter G c2 After(s), obtaining u in the MMC-STATCOM port ab 2 harmonic component u ab_ham2 2 th harmonic component u ab_ham2 By a gain element k 2 Obtaining a harmonic current instruction i of the 2-order harmonic additional control branch abref_ham2 . Wherein, the band-pass filter G c2 The center frequency of(s) is 2 fundamental frequencies.
And (3) making a difference between the harmonic current instruction of each phase and the instantaneous current of the bridge arm of the phase, and enabling the difference value to pass through a resonance controller to obtain each corresponding harmonic voltage instruction. Similarly, taking ab-phase and 2-th harmonic addition control branch as an example, harmonic current command i of 2-th harmonic addition control branch is added abref_ham2 Instantaneous current i of the phase bridge arm ab Making a difference, and passing the difference through a resonance controller R 100 Obtaining the corresponding harmonic voltage command e abref_ham2 。
And adding the harmonic voltage commands of each phase of all the added additional control branches to obtain the total harmonic voltage command of the phase. For example, fig. 2 adds the harmonic voltage commands obtained by the 2 nd harmonic addition control branch, the 3 rd harmonic addition control branch, the 4 th harmonic addition control branch and the n th harmonic addition control branch to obtain a total harmonic voltage command e of the phase abref_ham 。
And adding the total harmonic voltage instruction to an output value of a primary current controller in the MMC-STATCOM so as to inhibit low-order harmonic oscillation of the direct current converter station. That is, the control logic of fig. 2 is added to the control logic of fig. 3 to adjust the output of the current controller in the MMC-STATCOM to suppress the low harmonic instability of the dc converter station.
In order to more intuitively understand the implementation steps of the present invention, the present invention further provides a flow chart of another embodiment of the control method for low-order harmonic oscillation of a dc power station, and refer to fig. 4 specifically. The implementation of the present invention can be more intuitively understood from fig. 4.
According to the control method for low-order harmonic oscillation of the direct current station, provided by the embodiment of the invention, the additional control branch corresponding to different-frequency harmonics is additionally arranged on the original current controller to carry out filtering, gain and resonance control on the waveform of the bus voltage, so that the low-order harmonic oscillation of the direct current converter station is inhibited, and the direct current converter station can run more stably and safely.
As an improvement of the above scheme, whether the additional control branch is put into operation or not is controlled by an identification variable, and when the identification variable is set to be at a high level, the additional control branch is put into operation; when the identification variable is set to a low level, the additional control branch is not put into operation.
Specifically, whether the additional control branch is put into operation or not is controlled by an identification variable, and when the identification variable is set to be a high level, the additional control branch is put into operation; when the identification variable is set to a low level, the additional control branch is not put into operation. g n Adding an identification variable for controlling whether the branch is put into or not to the n-th harmonic wave when g is n If the value is not less than 1, the input of the n-th harmonic additional control branch is shown, and if the value is g n And if =0, the n-th harmonic addition control branch is not input. That is, a selector is connected behind the resonant controller in fig. 2, the selector performs selection according to an input level signal, and when the identification variable is at a high level, the selector selects to connect the additional control branch; when the identification variable is low, the selector selects to switch in another branch, i.e. not to add additional control.
As an improvement of the scheme, the frequency of the low-order harmonic is n, n is a positive integer, and n is larger than or equal to 2 and smaller than 10.
Specifically, the frequency of the low harmonic is n, n is a positive integer, and n is more than or equal to 2 and less than 10. The low order harmonics are determined on the basis of harmonics of the dc converter station that have occurred in actual operation.
As an improvement of the scheme, the expression of the band-pass filter is
Wherein, a n ，b n ，c n ，d n ，e n ，f n Respectively constant coefficients to be determined in the design process of the band-pass filter, and their design values are a n ＝(ω z -20π) 2 ，
d n ＝(ω z +20π) 2 ，
ω z ＝2×50π*n，ω z The angular frequency of the low order harmonics to be suppressed.
Specifically, the band pass filter is expressed as
Wherein, the band-pass filter G cn (s) has a center frequency n times the fundamental frequency, a n ，b n ，c n ，d n ，e n ，f n Constant coefficients to be determined during the design of the band-pass filter, respectively, with a design value of n ＝(ω z -20π) 2 ，
d n ＝(ω z +20π) 2 ，
ω z ＝2×50π*n，ω z The angular frequency of the low order harmonics to be suppressed.
In general, a n 、b n 、c n 、d n 、e n And f n The above expression is determined for a grid with a fundamental frequency of 50Hz, if the fundamental frequency changes, a n 、b n 、c n 、d n 、e n And f n The expression of (c) is adjusted.
To deepenFor an understanding of the present invention, a dc converter station system equipped with a STATCOM is described in detail below. Referring to fig. 5, a schematic structural diagram of an embodiment of a dc converter station system equipped with a STATCOM according to the present invention is shown. In FIG. 5, V DC And I DC Respectively, DC voltage and DC current, V, of a DC transmission system AC Is effective value of AC bus voltage, P, of DC converter station AC And Q AC Active and reactive power, Q, respectively, exchanged between the DC converter station and the AC network ST And outputting the total reactive power to the AC bus of the converter station for the STATCOM.
In practical engineering, the MMC-STATCOM generally adopts a triangle connection mode, and referring to fig. 6, the invention is a schematic diagram of an embodiment of a topology structure of the MMC-STATCOM in the triangle connection mode. The MMC-STATCOM in the triangular connection mode is formed by connecting three-phase bridge arms end to end, and each phase of bridge arm is formed by mutually connecting N Sub-modules (SM) with the same structure and bridge arm reactances at two ends. The MMC-STATCOM Sub-Module adopts a Full-Bridge structure, which is called Full Bridge Sub-Module (FBSM), u ab ，u bc ，u ca Instantaneous voltage difference i between two ends of each phase of bridge arm of MMC-STATCOM ab ，i bc ，i ca Respectively the instantaneous current on each phase of bridge arm.
In engineering, a direct current converter station MMC-STATCOM based on a triangular connection mode generally adopts split-phase control, namely instantaneous current of each phase of bridge arm is independently controlled. Referring to fig. 7, it is a general control logic diagram of an embodiment of a dc converter station based on delta connection provided by the present invention. I in FIG. 7 dref And I qref Respectively an active current instruction and a reactive current instruction of the MMC-STATCOM,
are each u ab ，u bc ，u ca The voltage phase i output by the MMC-STATCOM voltage phase detection link abref ，i bcref ，i caref Control of three-phase bridge arm instantaneous current of MMC-STATCOM respectivelyReference value, e abref1 ，e bcref1 ，e caref1 Controller outputs e of instantaneous current control links of ab phase, bc phase and ca phase respectively abref ，e bcref ，e caref And the reference signals are three-phase modulation wave reference signals of output voltage of the MMC-STATCOM respectively. Under normal working condition, I of MMC-STATCOM qref Control output derived from constant reactive power control, i.e. control mode flag =0, whereas in transient conditions, I of MMC-STATCOM qref The control output may be derived from the transient voltage control, i.e. the control mode flag may be switched from 0 to 1 in the transient condition.
And when no additional control is available, the main function of the direct current converter station MMC-STATCOM is dynamic compensation of reactive power. The reactive power compensation quantity of the MMC-STATCOM depends on a reactive current instruction I qref And the final tracking realization of the reactive current instruction is based on an instantaneous current control link. When the MMC-STATCOM has no additional control, the basic control block diagram of the instantaneous current control link can be seen in fig. 3.
In order to verify the low-order harmonic suppression effect of the invention, the invention respectively simulates the two conditions of no additional control and additional control. Referring to fig. 8, a schematic diagram of comparison of waveforms of effective voltage values of a bus of a converter station after a short-circuit fault before and after the low-order harmonic additional control branch of a certain dc converter station MMC-STATCOM provided by the present invention is put into operation is shown. The solid line is a waveform corresponding to that the MMC-STATCOM does not input the additional control branch, and the dotted line is a waveform corresponding to that the MMC-STATCOM inputs the additional control branch. From fig. 8, when the MMC-STATCOM is not put into an additional control branch, the waveform of the effective value of the bus voltage of the converter station contains a large amount of low-order harmonics, and the harmonic component is not attenuated for a long time. After the additional control branch is added into the MMC-STATCOM, the attenuation speed of the low-order harmonic component in the bus voltage of the direct current converter station is obviously accelerated, and the low-order harmonic in the near area of the converter station becomes stable.
Referring to fig. 9, it is a schematic structural diagram of an embodiment of the control apparatus for low-order harmonic oscillation of a dc power station provided in the present invention, the apparatus includes:
the waveform acquisition module 11 is configured to acquire a bus voltage waveform of the dc converter station, and determine a frequency of a low-order harmonic contained in a waveform according to the bus voltage waveform;
a branch input module 12, configured to determine to input an additional control branch corresponding to the frequency according to the determined frequency of the low-order harmonic; the additional control branch is added to an original current controller in an MMC-STATCOM of the direct current converter station and comprises a band-pass filter, a gain link and a resonance controller;
the electric quantity acquisition module 13 is used for acquiring a three-phase instantaneous line voltage at the MMC-STATCOM grid-connected port and an instantaneous current corresponding to a three-phase bridge arm;
a filtering gain module 14, configured to, in any one of the added control branches, pass the instantaneous line voltage of each phase through the band-pass filter and the gain element, respectively, to obtain each corresponding harmonic current instruction;
the resonance control module 15 is configured to make a difference between the harmonic current instruction of each phase and the instantaneous current of the bridge arm of the phase, and obtain each corresponding harmonic voltage instruction by passing the difference through the resonance controller;
the superposition module 16 is configured to add the harmonic voltage commands of each phase of all the added control branches to obtain a total harmonic voltage command of the phase;
and the output module 17 is configured to attach the total harmonic voltage instruction to an output value of the original current controller in the MMC-STATCOM, so as to suppress low-order harmonic oscillation of the dc converter station.
The control device for low-order harmonic oscillation of a dc station according to the embodiment of the present invention can implement all processes of the control method for low-order harmonic oscillation of a dc station according to any one of the embodiments, and the functions and technical effects of the modules and units in the device are respectively the same as those of the control method for low-order harmonic oscillation of a dc station according to the embodiment, and are not described herein again.
Referring to fig. 10, the present invention is a schematic structural diagram of an embodiment of an apparatus for a control method using dc station low-order harmonic oscillation, where the apparatus for the control method using dc station low-order harmonic oscillation includes a processor 10, a memory 20, and a computer program stored in the memory 20 and configured to be executed by the processor 10, and when the processor 10 executes the computer program, the processor implements the control method using dc station low-order harmonic oscillation according to any of the above embodiments.
Illustratively, the computer program may be divided into one or more modules/units, which are stored in the memory 20 and executed by the processor 10 to implement the present invention. One or more of the modules/units may be a series of computer program instruction segments capable of performing specific functions, which are used to describe the execution of a computer program in a control method for low harmonic oscillation of a dc plant. For example, the computer program may be divided into a waveform obtaining module, a branch input module, an electrical quantity obtaining module, a filter gain module, a resonance control module, a superposition module, and an output module, where the specific functions of the modules are as follows:
the waveform obtaining module 11 is configured to obtain a bus voltage waveform of the dc converter station, and determine a frequency of a low-order harmonic contained in the waveform according to the bus voltage waveform;
a branch input module 12, configured to determine, according to the determined frequency of the low-order harmonic, to input an additional control branch corresponding to the frequency; the additional control branch is added to a primary current controller in an MMC-STATCOM of the direct current converter station and comprises a band-pass filter, a gain link and a resonance controller;
the electric quantity acquisition module 13 is used for acquiring three-phase instantaneous line voltage at the MMC-STATCOM grid-connected port and instantaneous current corresponding to a three-phase bridge arm;
a filtering gain module 14, configured to, in any one of the added control branches, pass the instantaneous line voltage of each phase through the band-pass filter and the gain element, respectively, to obtain each corresponding harmonic current instruction;
the resonance control module 15 is configured to make a difference between the harmonic current instruction of each phase and the instantaneous current of the bridge arm of the phase, and obtain each corresponding harmonic voltage instruction by passing the difference through the resonance controller;
the superposition module 16 is configured to add the harmonic voltage commands of each phase of all the added control branches to obtain a total harmonic voltage command of the phase;
and the output module 17 is configured to attach the total harmonic voltage instruction to an output value of a primary current controller in the MMC-STATCOM, so as to suppress low-order harmonic oscillation of the dc converter station.
The device using the control method of the low-order harmonic oscillation of the direct current station can be computing equipment such as a desktop computer, a notebook computer, a palm computer and a cloud server. The device using the control method of the direct current station low harmonic oscillation can comprise, but is not limited to, a processor and a memory. It will be understood by those skilled in the art that the schematic diagram 10 is merely an example of an apparatus using the control method of low harmonic oscillation of the dc plant, and does not constitute a limitation of the apparatus using the control method of low harmonic oscillation of the dc plant, and may include more or less components than those shown, or combine some components, or different components, for example, the apparatus using the control method of low harmonic oscillation of the dc plant may further include input and output devices, network access devices, buses, and the like.
The Processor 10 may be a Central Processing Unit (CPU), other general purpose Processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field-Programmable Gate Array (FPGA) or other Programmable logic device, discrete Gate or transistor logic device, discrete hardware component, etc. The general purpose processor may be a microprocessor or the processor 10 may be any conventional processor or the like, the processor 10 being the control center of the apparatus using the control method for low order harmonic oscillation of a dc plant, various interfaces and lines connecting the various parts of the apparatus using the control method for low order harmonic oscillation of a dc plant as a whole.
The memory 20 may be used to store the computer programs and/or modules, and the processor 10 implements various functions of the apparatus using the control method for low order harmonic oscillation of a dc plant by operating or executing the computer programs and/or modules stored in the memory 20 and calling up the data stored in the memory 20. The memory 20 may mainly include a storage program area and a storage data area, wherein the storage program area may store an operating system, an application program required for at least one function (such as a sound playing function, an image playing function, etc.), and the like; the storage data area may store data (such as audio data, a phonebook, etc.) created according to the use of the cellular phone, etc. In addition, the memory 20 may include high speed random access memory, and may also include non-volatile memory, such as a hard disk, a memory, a plug-in hard disk, a Smart Media Card (SMC), a Secure Digital (SD) Card, a Flash memory Card (Flash Card), at least one magnetic disk storage device, a Flash memory device, or other volatile solid state storage device.
Wherein, the device integrated module of the control method for low harmonic oscillation of DC station can be stored in a computer readable storage medium if it is realized in the form of software functional unit and sold or used as independent product. Based on such understanding, all or part of the flow in the method according to the embodiments of the present invention may also be implemented by a computer program instructing related hardware, where the computer program may be stored in a computer-readable storage medium, and when the computer program is executed by a processor, the steps of the method embodiments may be implemented. The computer program includes computer program code, and the computer program code may be in a source code form, an object code form, an executable file or some intermediate form. The computer readable medium may include: any entity or device capable of carrying computer program code, recording medium, U.S. disk, removable hard disk, magnetic disk, optical disk, computer Memory, read-Only Memory (ROM), random Access Memory (RAM), electrical carrier wave signals, telecommunications signals, software distribution media, and the like. It should be noted that the computer readable medium may contain other components which may be suitably increased or decreased as required by legislation and patent practice in jurisdictions, for example, in some jurisdictions, in accordance with legislation and patent practice, the computer readable medium does not include electrical carrier signals and telecommunications signals.
The embodiment of the present invention further provides a computer-readable storage medium, where the computer-readable storage medium includes a stored computer program, where when the computer program runs, a device in which the computer-readable storage medium is located is controlled to execute the method for controlling low-order harmonic oscillation of a dc station according to any one of the above embodiments.
In summary, according to the method, the apparatus, and the storage medium for controlling low-order harmonic oscillation of a dc station provided in the embodiments of the present invention, the additional control branches corresponding to different frequency-order harmonics are added to the original current controller to perform filtering, gain, and resonance control on the bus voltage waveform, so as to suppress low-order harmonic oscillation of the dc converter station, and make the dc converter station operate more stably and safely. The method is provided based on the MM-STATCOM, can be applied to a high-voltage direct-current transmission scene, and helps to inhibit the low-order harmonic instability phenomenon of a direct-current converter station.
While the foregoing is directed to the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention.
Claims (6)
1. A control method for low-order harmonic oscillation of a direct current station is characterized by comprising the following steps:
acquiring a bus voltage waveform of a direct current converter station, and determining the frequency of low-order harmonic contained in the waveform according to the bus voltage waveform;
determining an additional control branch corresponding to the frequency according to the determined frequency of the low harmonic; the additional control branch is added to an original current controller in an MMC-STATCOM of the direct current converter station and comprises a band-pass filter, a gain link and a resonance controller;
acquiring three-phase instantaneous line voltage at the MMC-STATCOM grid-connected port and instantaneous current of a corresponding three-phase bridge arm;
in any one of the added control branches, the instantaneous line voltage of each phase passes through the band-pass filter and the gain link respectively to obtain each corresponding harmonic current instruction;
making a difference between the harmonic current instruction of each phase and the instantaneous current of the bridge arm of the phase, and enabling the difference value to pass through the resonance controller to obtain each corresponding harmonic voltage instruction;
adding the harmonic voltage commands of each phase of all the added control branches to obtain a total harmonic voltage command of the phase;
adding the total harmonic voltage instruction to an output value of a primary current controller in the MMC-STATCOM to inhibit low-order harmonic oscillation of the direct current converter station;
wherein the band-pass filter has an expression of
Wherein, a n ，b n ，c n ，d n ，e n ，f n Respectively constant coefficients to be determined in the design process of the band-pass filter, and their design values are a n ＝(ω z -20π) 2 ，
d n ＝(ω z +20π) 2 ，
ω z ＝2×50π*n，ω z The angular frequency of the low order harmonics to be suppressed.
2. The method of claim 1, wherein the activation or deactivation of the additional control branch is controlled by an identification variable, and the additional control branch is activated when the identification variable is set to a high level; when the identification variable is set to a low level, the additional control branch is not put into operation.
3. The method of claim 1, wherein the low harmonic has a frequency n, n is a positive integer, and 2 ≦ n < 10.
4. A control device for low harmonic oscillation of a DC station, comprising:
the waveform acquisition module is used for acquiring the bus voltage waveform of the direct current converter station and determining the frequency of low-order harmonics contained in the waveform according to the bus voltage waveform;
the branch input module is used for determining to input an additional control branch corresponding to the frequency according to the determined frequency of the low-order harmonic; the additional control branch is added to an original current controller in an MMC-STATCOM of the direct current converter station and comprises a band-pass filter, a gain link and a resonance controller;
the electric quantity acquisition module is used for acquiring three-phase instantaneous line voltage at the MMC-STATCOM grid-connected port and instantaneous current corresponding to a three-phase bridge arm;
the filtering gain module is used for enabling the instantaneous line voltage of each phase to respectively pass through the band-pass filter and the gain link in any one added control branch circuit to obtain each corresponding harmonic current instruction; wherein the band-pass filter has an expression of
Wherein, a n ，b n ，c n ，d n ，e n ，f n Respectively constant coefficients to be determined in the design process of the band-pass filter, and their design values are a n ＝(ω z -20π) 2 ，
d n ＝(ω z +20π) 2 ，
ω z ＝2×50π*n，ω z Angular frequency of the low order harmonics to be suppressed;
the resonance control module is used for making a difference between the harmonic current instruction of each phase and the instantaneous current of the bridge arm of the phase, and the difference value is passed through the resonance controller to obtain each corresponding harmonic voltage instruction;
the superposition module is used for adding the harmonic voltage commands of each phase of all the added additional control branches to obtain a total harmonic voltage command of the phase;
and the output module is used for attaching the total harmonic voltage instruction to an output value of a primary current controller in the MMC-STATCOM so as to inhibit low-order harmonic oscillation of the direct current converter station.
5. An apparatus using a control method of dc plant low order harmonic oscillations, characterized in that it comprises a processor, a memory and a computer program stored in said memory and configured to be executed by said processor, said processor when executing said computer program implementing the control method of dc plant low order harmonic oscillations according to any of the claims 1 to 3.
6. A computer-readable storage medium, comprising a stored computer program, wherein the computer program, when executed, controls an apparatus in which the computer-readable storage medium is located to perform the method for controlling dc station low order harmonic oscillation according to any one of claims 1 to 3.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010901446.7A CN112018773B (en) | 2020-08-31 | 2020-08-31 | Control method and device for low-order harmonic oscillation of direct current station and storage medium |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010901446.7A CN112018773B (en) | 2020-08-31 | 2020-08-31 | Control method and device for low-order harmonic oscillation of direct current station and storage medium |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN112018773A CN112018773A (en) | 2020-12-01 |
| CN112018773B true CN112018773B (en) | 2023-02-24 |
Family
ID=73516504
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202010901446.7A Active CN112018773B (en) | 2020-08-31 | 2020-08-31 | Control method and device for low-order harmonic oscillation of direct current station and storage medium |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN112018773B (en) |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105210283A (en) * | 2013-04-26 | 2015-12-30 | 富士电机株式会社 | Resonance suppression device |
| CN110445148A (en) * | 2019-08-13 | 2019-11-12 | 南昌工程学院 | A kind of proportional resonant control method of high-voltage chain type STATCOM |
-
2020
- 2020-08-31 CN CN202010901446.7A patent/CN112018773B/en active Active
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105210283A (en) * | 2013-04-26 | 2015-12-30 | 富士电机株式会社 | Resonance suppression device |
| CN110445148A (en) * | 2019-08-13 | 2019-11-12 | 南昌工程学院 | A kind of proportional resonant control method of high-voltage chain type STATCOM |
Non-Patent Citations (2)
| Title |
|---|
| 电网畸变条件下基于LCL型滤波的STATCOM电流控制策略研究;刘俊等;《电力与能源》;20141220(第06期);全文 * |
| 电网谐波对级联STATCOM运行影响分析及抑制;杨明等;《电力电子技术》;20160820(第08期);全文 * |
Also Published As
| Publication number | Publication date |
|---|---|
| CN112018773A (en) | 2020-12-01 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN110943456B (en) | Small signal harmonic state space modeling method and device for LCC-HVDC system | |
| CN109842126B (en) | Stable control method for suppressing voltage oscillation of flexible direct current transmission system | |
| Das et al. | Improvement in power quality using hybrid power filters based on RLS algorithm | |
| De Kooning et al. | Grid voltage control with distributed generation using online grid impedance estimation | |
| Huang et al. | A delta-connected MMCC-based active power conditioner for unbalanced load compensation and harmonic elimination | |
| CN109406854B (en) | Harmonic instruction current obtaining method, device and equipment of single-phase active filter | |
| JP3822910B2 (en) | Reduction of power line harmonics by hybrid parallel active / passive filter system with square wave inverter and DC bus control | |
| Cleary-Balderas et al. | Hybrid active power filter based on the IRP theory for harmonic current mitigation | |
| CN112018773B (en) | Control method and device for low-order harmonic oscillation of direct current station and storage medium | |
| CN117375015A (en) | Electric energy quality control device and method | |
| Yue et al. | Robust predictive dual-loop control method based on Lyapunov function stability and energy equilibrium though double-core processors for active power filter | |
| Pan et al. | LCL APF based on fractional-order fast repetitive control strategy | |
| CN110034580B (en) | Proportional reduced-order resonance control strategy method of inverter under unbalanced grid voltage | |
| CN114865680A (en) | Specific resonant frequency suppression method of modular multilevel converter | |
| Fereidouni et al. | A new space-vector Hysteresis current-control modulation for active power filter applications | |
| Wang et al. | Design and analysis of single-phase adaptive passive part coupling hybrid active power filter (HAPF) | |
| Gupta et al. | Performance of distributed power flow controller on system behavior under unbalance fault condition | |
| CN114285050A (en) | Method and device for suppressing direct current side oscillation of flexible direct current transmission system and storage medium | |
| Nagotha et al. | Hybrid shunt active filter offering unity power factor and low THD at line side with reduced power rating | |
| Roldan-Perez et al. | Discrete-time resonant controllers design for power conditioning applications | |
| CN117650495B (en) | Flexible AC traction converter contact net fault transient voltage suppression method and device | |
| CN112600445B (en) | Control method and device of three-level rectifier circuit and terminal equipment | |
| CN107528318B (en) | Control method for avoiding divergence during APF compensation of capacitive nonlinear load | |
| CN112701946B (en) | MMC bridge arm current balance control method and control system | |
| Kyaw | Power Quality Improvement, Load Balancing |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |