CN110581640B - Control method and system of multi-module direct parallel converter and storage medium - Google Patents
Control method and system of multi-module direct parallel converter and storage medium Download PDFInfo
- Publication number
- CN110581640B CN110581640B CN201810594989.1A CN201810594989A CN110581640B CN 110581640 B CN110581640 B CN 110581640B CN 201810594989 A CN201810594989 A CN 201810594989A CN 110581640 B CN110581640 B CN 110581640B
- Authority
- CN
- China
- Prior art keywords
- current
- target
- module
- phase
- subharmonic
- 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
Images
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/12—Arrangements for reducing harmonics from ac input or output
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Inverter Devices (AREA)
Abstract
The invention discloses a control method of a multi-module direct parallel converter, which comprises the following steps: determining the product of the number of the current transformation modules connected in parallel on the alternating-current winding of the transformer and the current phase number of a single current transformation module; determining the quotient of 360 degrees and the product as a target angle; and staggering each phase carrier loaded on each current transformation module so as to enable the phase of each phase carrier to sequentially differ by a target angle. By applying the control method of the multi-module direct parallel converter provided by the invention, high-frequency harmonic waves near the switching frequency can be reduced in the multi-module direct parallel converter, and the active power output by the system is greatly improved. The invention also provides a control system of the multi-module direct parallel converter and a computer readable storage medium, and the control system has corresponding technical effects.
Description
Technical Field
The invention relates to the technical field of power electricity, in particular to a control method and a control system for a multi-module direct parallel converter and a storage medium.
Background
With the continuous development of society and science and technology, the demands on the quality and capacity of electric power automation equipment are increasing on a daily basis in various occasions such as an electric vehicle driving system, a distributed power generation and power supply system, and an electric power dragging system, and the improvement of the output performance of a converter is one of important research directions.
The converter usually includes a plurality of converter modules, which are connected in parallel to the transformer, due to the limitation of the capacity of the power device. The plurality of converter modules have the advantages of increasing the power level of the system output, improving the reliability of the system, increasing the flexibility of the system and the like.
In the prior art, one solution is to connect a plurality of converter modules in parallel to a plurality of ac secondary windings of a transformer. Because the multi-winding transformer is adopted to realize electrical isolation, the circulation between modules can be avoided, but the method has higher process requirements on transformer manufacturers, and the cost is higher when the number of windings is more. Meanwhile, the size of the transformer in the mode is much larger than that of a single-winding transformer, and the transformer is difficult to popularize in places with limited space, such as subway substations, motor train transformers and the like.
Another solution is to connect a plurality of converter modules directly in parallel to the converter, i.e. still using a conventional single winding transformer. Due to the fact that impedance of each current transformation module is different, voltage difference exists between the modules, and circulation currents among the modules can be caused. The existence of the circulation can increase the electric energy loss, and the electric energy loss needs to be eliminated, usually, the circulation is subjected to closed-loop control through a control algorithm, but the method only has a certain effect on low-frequency harmonics, but cannot eliminate high-frequency harmonics near the switching frequency in the circulation, the suppression effect has certain coupling with system parameters, and when the system parameters are changed and reach a certain critical value, oscillation between the low frequency and the high frequency of the system can be caused.
In summary, how to reduce the high-frequency harmonic near the switching frequency in the multi-module direct parallel converter is a technical problem that needs to be solved urgently by those skilled in the art.
Disclosure of Invention
The invention aims to provide a control method, a system and a storage medium of a multi-module direct parallel converter, so as to reduce high-frequency harmonic waves near a switching frequency in the multi-module direct parallel converter.
In order to solve the technical problems, the invention provides the following technical scheme:
a control method of a multi-module direct parallel converter comprises the following steps:
determining the product of the number of the current transformation modules connected in parallel on the alternating-current winding of the transformer and the current phase number of a single current transformation module;
determining a quotient of 360 ° and the product as a target angle;
and staggering each phase carrier loaded on each current transformation module so as to enable the phase of each phase carrier to sequentially differ by the target angle.
Preferably, the method further comprises the following steps:
extracting preset target subharmonic current;
inputting the target subharmonic current as a feedback quantity into a regulator corresponding to the target subharmonic current;
and converting the target subharmonic current regulating quantity output by the regulator into a voltage quantity, and then superposing the voltage quantity with a fundamental wave voltage to be used as a synthesized reference voltage output quantity so as to generate a compensation current for offsetting the target subharmonic current.
Preferably, the carrier wave is an isosceles triangle wave.
Preferably, the extracting the preset target subharmonic current includes:
and extracting preset target subharmonic current from the circulating current.
Preferably, the extracting the preset target subharmonic current from the circulating current includes:
extracting a sine component and a cosine component of the target subharmonic current from the circulating current respectively;
taking the sum of the sine component and the cosine component as the extracted target subharmonic current.
Preferably, the extracting the sine component and the cosine component of the target subharmonic current from the circulating current respectively includes:
multiplying the circulating current by 2sinNwt and inputting the product to a first low-pass filter;
multiplying the direct current output of the first low-pass filter by sinNwt as the sinusoidal component of the target subharmonic current;
multiplying the circulating current by 2cosNwt and inputting the product to a second low-pass filter;
multiplying the direct current output of the second low-pass filter by cosNwt to obtain a cosine component of the target subharmonic current;
wherein N is the number of times of the target subharmonic current, w is the frequency of the circulating current, and t is time.
Preferably, the regulator is a proportional resonant regulator.
A control system for a multi-module direct parallel converter, the system comprising:
the product determining module is used for determining the product of the number of the current converting modules connected in parallel on the alternating-current winding of the transformer and the current phase number of a single current converting module;
a target angle determination module for determining a quotient of 360 ° and the product as a target angle;
and the carrier phase shifting module is used for staggering each phase carrier loaded on each current transformation module so as to enable the phase of each phase carrier to be sequentially different by the target angle.
Preferably, the method further comprises the following steps:
the target subharmonic current extraction module is used for extracting preset target subharmonic current;
a feedback quantity input module for inputting the target subharmonic current as a feedback quantity to a regulator corresponding to the target subharmonic current;
and the voltage conversion module is used for converting the target subharmonic current regulating quantity output by the regulator into a voltage quantity and then superposing the voltage quantity with a fundamental wave voltage to be used as a synthesized reference voltage output quantity so as to generate a compensation current for offsetting the target subharmonic current.
A computer readable storage medium having stored thereon a converter circulating current control program, which when executed by a processor implements the steps of any of the above-described methods for controlling a multi-module direct parallel converter.
The technical scheme provided by the embodiment of the invention comprises the following steps: determining the product of the number of the current transformation modules connected in parallel on the alternating-current winding of the transformer and the current phase number of a single current transformation module; determining the quotient of 360 degrees and the product as a target angle; and staggering each phase carrier loaded on each current transformation module so as to enable the phase of each phase carrier to sequentially differ by a target angle.
The product of the number of the current transformation modules and the current phase number of a single current transformation module is multiplied by a target angle to be equal to 360 degrees, namely, each phase carrier loaded on each current transformation module is uniformly distributed according to the phase difference of the target angle in sequence in one period of the carrier. The carrier wave and the modulation wave are signal-modulated to generate pulse waves, and each phase of the carrier wave is sequentially staggered by a target angle, so that each generated phase of the pulse waves is also sequentially staggered by a corresponding target angle. The pulse wave comprises high-frequency harmonics near the switching frequency, the frequency of the high-frequency harmonics is close to the switching frequency, namely the carrier frequency, when the high-frequency harmonics are sequentially staggered from a target angle, for the high-frequency harmonics near the switching frequency contained in any one phase of pulse wave, corresponding high-frequency harmonics in another phase of pulse wave with the phase difference of about 180 degrees are offset with the high-frequency harmonics, and therefore the scheme of the application can reduce the high-frequency harmonics near the switching frequency in the converter with the multiple modules directly connected in parallel, and the active power output by the system is greatly improved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a flowchart illustrating an embodiment of a method for controlling a multi-module direct parallel converter according to the present invention;
FIG. 2 is a system topology diagram of multiple modules directly connected in parallel in accordance with an embodiment of the present invention;
FIG. 3 is a schematic carrier phase shift diagram of two modules according to an embodiment of the present invention;
FIG. 4 is a schematic diagram illustrating the control of low frequency harmonic currents in an embodiment of the present invention;
FIG. 5 is a schematic diagram of low frequency harmonic extraction according to an embodiment of the present invention;
fig. 6 is a schematic structural diagram of a control system of a multi-module direct parallel converter according to the present invention.
Detailed Description
The core of the invention is to provide a control method of a multi-module direct parallel converter, which can reduce high-frequency harmonic near the switching frequency in the multi-module direct parallel converter, and greatly improve the active power output by the system.
In order that those skilled in the art will better understand the disclosure, the invention will be described in further detail with reference to the accompanying drawings and specific embodiments. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. 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, fig. 1 is a flowchart illustrating an implementation of a method for controlling a multi-module direct parallel converter according to the present invention, where the method includes the following steps:
s101: the product of the number of converter modules connected in parallel to the ac winding of the transformer and the number of current phases of a single converter module is determined.
The product determined in step S101 is the sum of the current phases of the current modules connected in parallel to the ac winding of the transformer, which is convenient to understand, in this application, the parallel connection of two current modules is taken as an example for description, and a topological schematic diagram of a system in which two current modules are connected in parallel may be referred to fig. 2. In fig. 2, two inverter modules are a module-one VSC1 and a module-two VSC2, respectively, a1, B1 and C1 on the three-phase ac side of the module-one and a2, B2 and C2 on the three-phase ac side of the module-two are connected in parallel to a three-phase power supply directly through reactors LA1, LB1, LC1, LA2, LB2 and LC2, respectively, that is, the ac winding of the transformer, the dc sides of the two modules are connected in parallel to a load through capacitors C1 and C2, and the load is represented by a resistor R. In the embodiment of fig. 2, the number of converter modules connected in parallel to the ac winding of the transformer is 2, and the current phase number of a single converter module is 3, then the product is 6, i.e. the sum of the current phase numbers of the converter modules connected in parallel to the ac winding of the transformer is 6.
It should be noted that, in this embodiment, the number of current phases of the current transforming module is 3, that is, a common three-phase power supply system is also applicable to single-phase power. It should be emphasized that fig. 2 is a system topology diagram of multiple modules directly connected in parallel in an embodiment, and in practical applications, specific circuit configuration and adjustment can be performed according to practical situations without affecting the implementation of the present invention, such as the type of load, the type and configuration of semiconductor devices, and the like.
S102: the quotient of 360 ° and the product is determined as the target angle.
In the embodiment of fig. 2, since the product determined in step S101 is 6, the quotient of 360 ° and the product is 60 °, i.e., the target angle is determined to be 60 °. It should be noted that, in the embodiment of the present invention, the target angle obtained in step S102 may be adjusted to a certain extent according to actual conditions, for example, the target angle may be adjusted to a certain extent based on actual data statistics, theoretical analysis, and other manners according to factors such as the difference in the number of the parallel converter modules and the difference in the frequency of the main high-frequency harmonic in the actual conditions.
S103: and staggering each phase carrier loaded on each current transformation module so as to enable the phase of each phase carrier to sequentially differ by a target angle.
The carrier is used for generating a pulse wave with the modulation wave, and the carrier loaded on each phase current of each converter module is generally the same carrier, i.e. the phase, frequency and peak value of the carrier are the same. In step S103, the carriers of the respective phases are shifted so that the phases of the carriers of the respective phases are sequentially different by a target angle.
Still taking the system of fig. 2 in which two modules are connected in parallel as an example for description, refer to fig. 3, which is a schematic diagram of carrier phase shift of the module one and the module two in the present invention. Because the horizontal width and the height of any point on the isosceles triangular wave are in linear relation and are bilaterally symmetrical, when the isosceles triangular wave intersects with any modulation signal wave which changes gently, if the on-off of a switching device in a circuit is controlled at the intersection point moment, a pulse with the width being in direct proportion to the amplitude of the signal wave can be obtained, namely, the pulse waveform can be conveniently obtained by adopting the isosceles triangular wave as a carrier wave, and therefore, the isosceles triangular wave can be usually selected as the carrier wave. Of course, the specific parameter setting of the carrier wave may be set and adjusted according to actual situations, for example, a unipolar or bipolar isosceles triangle wave is adopted, and a sawtooth wave is adopted as the carrier wave.
In fig. 3, the carriers of each phase loaded on the two modules are: vsa1, Vsb1, Vsc1, Vsa2, Vsb2 and Vsc 2. For convenience of description, the initial phase of each phase carrier is not taken as a reference phase, that is, the phase of each phase carrier is assumed to be 0 ° before the phase of each phase carrier is shifted. After the phase shift in sequence, the phase of each phase carrier differs by 60 ° in sequence. In the embodiment of fig. 3, after phase shifting, the phase of carrier Vsa1 is not considered to be still 0 °, i.e., carrier Vsa1 is not changed, the phase of Vsb1 is 120 ° out of phase with Vsa1, and the phase of Vsc1 is 240 °. Accordingly, in fig. 3, the phases of Vsa2, Vsb2, and Vsc2 are 180 °, 300 °, and 420 °, i.e., 60 °, in that order.
It should be noted that fig. 3 shows the phase shift of the carriers in a specific embodiment, and in other embodiments, the carriers of each phase may have other phases, as long as the phases of the carriers of each phase sequentially differ by a target angle after the phase shift is satisfied. For example, in one particular implementation of the above-described embodiment, after phase shifting, the phases of carriers Vsa1 are 10 °, carriers Vsb1, Vsc1, Vsa2, Vsb2, and Vsc2 are 70 °, 130 °, 190 °, 250 °, and 310 ° in sequence.
It should be noted that, in the embodiment of fig. 3, the phase carriers loaded on the two modules are Vsa1, Vsb1, Vsc1, Vsa2, Vsb2 and Vsc2 in sequence, the Vsa1 and the Vsc1 are not called adjacent phases, correspondingly, the Vsb1 and the Vsc1 are also adjacent phases, the phases of the phase carriers are sequentially different by a target angle, and the phase difference between the adjacent phases is not limited to the target angle, for example, in the above example, the phase of Vsa1 is 0 °, the phase of Vsb1 is 120 °, and the phase of Vsc2 is 60 °. However, in consideration of the fact that carrier phase shift affects the phase order of the fundamental current, the phase difference between two adjacent phases is generally made the same in the same module when carrier phase shift is performed. In the example above, the Vsa1, Vsb1, and Vsc1 of block one are sequentially phased at 0 °, 120 °, and 240 °, and in another example, the Vsa1, Vsb1, and Vsc1 are sequentially phased at 10 °, 70 °, and 130 °.
In the embodiment of fig. 3, since the carrier Vsa1 loaded on module one is 0 and the carrier Vsa2 loaded on module two is 180, the pulse a1 from module one is offset from the pulse a2 from module two by a distance equal to the 180 phase shift of the carrier as viewed in the image. That is, pulse a2 of module two is offset by the distance compared to pulse a1 of module one. Both pulse a1 and pulse a2 contain high frequency harmonics, so the high frequency harmonics in pulse a2 are also offset by this distance from the corresponding high frequency harmonics in pulse a 1. The high-frequency harmonics are mainly high-frequency harmonics in the vicinity of the switching frequency, for example, the carrier frequency is 21 times, and the main high-frequency harmonics are 19 times and 23 times, compared with the sinusoidal modulation wave, and since the frequencies of these high-frequency harmonics are close to the switching frequency, after the distance is shifted, the directions of the high-frequency harmonics in the pulse a1 and the corresponding high-frequency harmonics in the pulse a2 are opposite, and these high-frequency harmonics in the pulse a1 and the corresponding high-frequency harmonics in the pulse a2 cancel each other. Accordingly, the carrier Vsc2 having a phase of 60 ° and the modulated wave generating pulse C2, the carrier Vsc1 having a phase of 240 ° and the modulated wave generating pulse C1 cancel the high-frequency harmonic near the switching frequency included in the pulse C1 and the high-frequency harmonic corresponding to the pulse C2, and the same applies to the pulse B1 and the pulse B2, and description thereof will not be repeated here.
The method provided by the embodiment of the invention comprises the following steps: determining the product of the number of the current transformation modules connected in parallel on the alternating-current winding of the transformer and the current phase number of a single current transformation module; determining the quotient of 360 degrees and the product as a target angle; and staggering each phase carrier loaded on each current transformation module so as to enable the phase of each phase carrier to sequentially differ by a target angle.
The product of the number of the current transformation modules and the current phase number of a single current transformation module is multiplied by a target angle to be equal to 360 degrees, namely, each phase carrier loaded on each current transformation module is uniformly distributed according to the phase difference of the target angle in sequence in one period of the carrier. The carrier wave and the modulation wave are signal-modulated to generate pulse waves, and each phase of the carrier wave is sequentially staggered by a target angle, so that each generated phase of the pulse waves is also sequentially staggered by a corresponding target angle. The pulse wave comprises high-frequency harmonics near the switching frequency, the frequency of the high-frequency harmonics is close to the switching frequency, namely the carrier frequency, when the high-frequency harmonics are sequentially staggered from a target angle, for the high-frequency harmonics near the switching frequency contained in any one phase of pulse wave, corresponding high-frequency harmonics in another phase of pulse wave with the phase difference of about 180 degrees are offset with the high-frequency harmonics, and therefore the scheme of the application can reduce the high-frequency harmonics near the switching frequency in the converter with the multiple modules directly connected in parallel, and the active power output by the system is greatly improved.
In one embodiment of the present invention, the method further comprises the following steps:
the method comprises the following steps: extracting preset target subharmonic current;
step two: inputting the target subharmonic current as a feedback quantity into a regulator corresponding to the target subharmonic current;
step three: the target subharmonic current regulating quantity output by the regulator is converted into a voltage quantity and then is superposed with the fundamental wave voltage to be used as a synthesized reference voltage output quantity so as to generate a compensation current for offsetting the target subharmonic current.
In consideration of the fact that the circulating current also contains low-frequency harmonics, the low-frequency harmonics are processed in the embodiment of the invention to further reduce harmonic distortion of the converter. In specific implementation, a preset target subharmonic current can be extracted from the circulating current, and the circulating current can be extracted through a sensor. The preset target subharmonic current can be set according to actual conditions, for example, in fig. 4, when the target subharmonic current is 5 subharmonic current, the 5 subharmonic current is represented as I5grid_refAs a feedback quantity for the respective regulator. Since the PR regulator, i.e., the proportional resonant regulator, is easy to compensate for the low-order harmonic, the regulator in step two may be generally selected as the proportional resonant regulator, and of course, in specific implementation, other types of regulators may be selected according to actual needs. In FIG. 4I5grid_fdbA given amount of the 5 th harmonic current is indicated, typically set to 0, so that the 5 th harmonic current approaches 0 by adjustment of the respective regulator. Also shown in fig. 4 is the 7 th harmonic current, i.e., when the target second harmonic current is the 7 th harmonic current, the 7 th harmonic current may be input as a feedback amount into the regulator corresponding to the 7 th harmonic current. The first proportional resonant regulator in fig. 4, i.e., the regulator for regulating 5 th harmonic current, outputs a 5 th harmonic current regulation amount, which can be converted into a corresponding voltage amount by 5 WL. The 5WL may be a resistance in the current transformer. And superposing the converted voltage quantity and the fundamental wave voltage to be used as a synthesized reference voltage output quantity, wherein the synthesized reference voltage output quantity is a modulation wave for carrying out signal modulation with a carrier wave, so as to finally generate a compensation current for offsetting the target subharmonic current. In fig. 4, the fundamental voltage is expressed as uout, and when the voltages are superimposed, the fundamental voltage is superimposed as a vector.
It should be noted that since the low-frequency harmonics are mainly 5 th, 7 th, 11 th and 13 th harmonics, the 5 th, 7 th, 11 th and 13 th harmonic currents can be generally used as the target subharmonic currents, and of course, in the specific implementation, the target subharmonic currents can be set according to the actual situation, and do not affect the implementation of the present invention.
In an embodiment of the present invention, the step one may specifically include the following two steps:
the first step is as follows: extracting a sine component and a cosine component of the target subharmonic current from the circulating current respectively;
the second step is that: the sum of the sine component and the cosine component is taken as the extracted target subharmonic current.
For example, the circulating current is:
the 5 th harmonic current contained therein is i5(t), i5(t)＝I5pmsin5wt+I5qmcos5wt。
Thus, in a first step, the sinusoidal component of the 5 th harmonic current, i.e. I, is extracted from the circulating current5pmsin5wt, and the cosine component of the 5 th harmonic current, I5qmcos5wt, after extraction, the sum of the sine and cosine components is taken as the extracted 5 th harmonic current.
In a specific implementation, the first step may specifically include:
multiplying the circulating current by 2sinNwt and inputting the product to a first low-pass filter;
multiplying the direct current output of the first low-pass filter by sinNwt as the sinusoidal component of the target subharmonic current;
multiplying the circulating current by 2cosNwt, and inputting the product to a second low-pass filter;
multiplying the direct current output of the second low-pass filter by cosNwt to obtain a cosine component of the target subharmonic current;
where N is the number of times of the target subharmonic current, w is the frequency of the circulating current, and t is time.
For convenience of description, refer to FIG. 5, which shows that the circulating current is iLsinNwt can be obtained by a phase-locked loop, that is, sin5wt and cos5wt can be obtained by PLL in fig. 5, and after the circulating current is multiplied by 2sin5wt, the current is input to a first low-pass filter, and a direct-current component can be obtained. Due to i5(t)＝I5pmsin5wt+I5qmcos5wt, and 2i5(t)sin5wt＝I5pm-I5pmcos10wt+I5qmsin10wt, so the DC component of the output of the first low pass filter is I5pm. The DC output is multiplied by sin5wt to be I5pmsin5wt as the sinusoidal component of the 5 th harmonic current; correspondingly, the DC component output by the second low-pass filter is I5qmMultiplied by cos5wt and then given as I5qmcos5wt as the cosine component of the 5 th harmonic current.
Corresponding to the above method embodiment, the embodiment of the present invention further provides a control system of a multi-module direct parallel converter, and the control system of the multi-module direct parallel converter described below and the control system method of the multi-module direct parallel converter described above may be referred to correspondingly. Referring to fig. 6, a schematic structural diagram of a control system of a multi-module direct parallel converter according to the present invention is shown, where the system includes:
a product determining module 60, configured to determine a product of the number of converter modules connected in parallel to the ac winding of the transformer and the current phase number of a single converter module;
a target angle determination module 61 for determining a quotient of 360 ° and the product as a target angle;
and a carrier phase shift module 62, configured to stagger the phase carriers loaded on each current transformation module, so that the phases of the phase carriers sequentially differ by a target angle.
The system provided by the embodiment of the invention comprises the following components: the product determining module is used for determining the product of the number of the current converting modules connected in parallel on the alternating current winding of the transformer and the current phase number of a single current converting module; the target angle determining module is used for determining the quotient of the 360 degrees and the product as a target angle; and the carrier phase shifting module is used for staggering each phase carrier loaded on each current transformation module so as to enable the phase of each phase carrier to sequentially differ by a target angle.
The product of the number of the current transformation modules and the current phase number of a single current transformation module is multiplied by a target angle to be equal to 360 degrees, namely, each phase carrier loaded on each current transformation module is uniformly distributed according to the phase difference of the target angle in sequence in one period of the carrier. The carrier wave and the modulation wave are signal-modulated to generate pulse waves, and each phase of the carrier wave is sequentially staggered by a target angle, so that each generated phase of the pulse waves is also sequentially staggered by a corresponding target angle. The pulse wave comprises high-frequency harmonics near the switching frequency, the frequency of the high-frequency harmonics is close to the switching frequency, namely the carrier frequency, when the high-frequency harmonics are sequentially staggered from a target angle, for the high-frequency harmonics near the switching frequency contained in any one phase of pulse wave, corresponding high-frequency harmonics in another phase of pulse wave with the phase difference of about 180 degrees are offset with the high-frequency harmonics, and therefore the scheme of the application can reduce the high-frequency harmonics near the switching frequency in the converter with the multiple modules directly connected in parallel, and the active power output by the system is greatly improved.
In one embodiment of the present invention, the method further comprises:
the target subharmonic current extraction module is used for extracting preset target subharmonic current;
the feedback quantity input module is used for inputting the target subharmonic current into a regulator corresponding to the target subharmonic current as a feedback quantity;
and the voltage conversion module is used for converting the target subharmonic current regulating quantity output by the regulator into a voltage quantity and then superposing the voltage quantity with the fundamental wave voltage to be used as a synthesized reference voltage output quantity so as to generate a compensation current for offsetting the target subharmonic current.
In an embodiment of the present invention, the target subharmonic current extraction module is specifically configured to:
and extracting preset target subharmonic current from the circulating current.
In one embodiment of the invention, the target subharmonic current extraction module comprises the following two sub-modules:
a component extraction submodule: the device is used for extracting a sine component and a cosine component of the target subharmonic current from the circulating current respectively;
and the superposition submodule is used for taking the sum of the sine component and the cosine component as the extracted target subharmonic current.
In an embodiment of the present invention, the component extraction sub-module is specifically configured to:
multiplying the circulating current by 2sinNwt and inputting the product to a first low-pass filter;
multiplying the direct current output of the first low-pass filter by sinNwt as the sinusoidal component of the target subharmonic current;
multiplying the circulating current by 2cosNwt, and inputting the product to a second low-pass filter;
multiplying the direct current output of the second low-pass filter by cosNwt to obtain a cosine component of the target subharmonic current;
where N is the number of times of the target subharmonic current, w is the frequency of the circulating current, and t is time.
In one embodiment of the invention, the regulator is a proportional resonant regulator.
Corresponding to the above method and system embodiments, the present invention further provides a computer readable storage medium, on which a converter circulating current control program is stored, wherein the converter circulating current control program, when executed by a processor, implements the steps of the method for controlling a multi-module direct parallel converter according to any of the above embodiments, and the computer readable storage medium and the method and system for controlling a multi-module direct parallel converter described above are referred to correspondingly, and are not repeated herein.
The embodiments are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same or similar parts among the embodiments are referred to each other. The device disclosed by the embodiment corresponds to the method disclosed by the embodiment, so that the description is simple, and the relevant points can be referred to the method part for description.
Those of skill would further appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both, and that the various illustrative components and steps have been described above generally in terms of their functionality in order to clearly illustrate this interchangeability of hardware and software. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the implementation. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.
The steps of a method or algorithm described in connection with the embodiments disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module may reside in Random Access Memory (RAM), memory, Read Only Memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. The principle and the implementation of the present invention are explained in the present application by using specific examples, and the above description of the embodiments is only used to help understanding the technical solution and the core idea of the present invention. It should be noted that, for those skilled in the art, it is possible to make various improvements and modifications to the present invention without departing from the principle of the present invention, and those improvements and modifications also fall within the scope of the claims of the present invention.
Claims (10)
1. A control method for a multi-module direct parallel converter is characterized by comprising the following steps:
determining the product of the number of the current transformation modules connected in parallel on the alternating-current winding of the transformer and the current phase number of a single current transformation module;
determining a quotient of 360 ° and the product as a target angle;
and staggering each phase carrier loaded on each current transformation module so as to enable the phase of each phase carrier to sequentially differ by the target angle.
2. The method of claim 1, further comprising:
extracting preset target subharmonic current;
inputting the target subharmonic current as a feedback quantity into a regulator corresponding to the target subharmonic current;
and converting the target subharmonic current regulating quantity output by the regulator into a voltage quantity, and then superposing the voltage quantity with a fundamental wave voltage to be used as a synthesized reference voltage output quantity so as to generate a compensation current for offsetting the target subharmonic current.
3. The method of claim 1, wherein the carrier wave is an isosceles triangle wave.
4. The method of claim 2, wherein the extracting the predetermined target sub-harmonic current comprises:
and extracting preset target subharmonic current from the circulating current.
5. The method for controlling a multi-module direct parallel converter according to claim 4, wherein the extracting a preset target sub-harmonic current from a circulating current comprises:
extracting a sine component and a cosine component of the target subharmonic current from the circulating current respectively;
taking the sum of the sine component and the cosine component as the extracted target subharmonic current.
6. The method of claim 5, wherein the extracting the sine component and the cosine component of the target sub-harmonic current from the circulating current comprises:
multiplying the circulating current by 2sin Nwt and inputting the product to a first low-pass filter;
multiplying the direct current output of the first low-pass filter by sin Nwt as the sinusoidal component of the target subharmonic current;
multiplying the circulating current by 2cos Nwt, and inputting the product to a second low-pass filter;
multiplying the direct current output of the second low-pass filter by cos Nwt to obtain a cosine component of the target subharmonic current;
wherein N is the number of times of the target subharmonic current, w is the frequency of the circulating current, and t is time.
7. The method of claim 2, wherein the regulator is a proportional resonant regulator.
8. A control system of a multi-module direct parallel converter is characterized by comprising the following components:
the product determining module is used for determining the product of the number of the current converting modules connected in parallel on the alternating-current winding of the transformer and the current phase number of a single current converting module;
a target angle determination module for determining a quotient of 360 ° and the product as a target angle;
and the carrier phase shifting module is used for staggering each phase carrier loaded on each current transformation module so as to enable the phase of each phase carrier to be sequentially different by the target angle.
9. The control system of a multi-module direct parallel converter according to claim 8, further comprising:
the target subharmonic current extraction module is used for extracting preset target subharmonic current;
a feedback quantity input module for inputting the target subharmonic current as a feedback quantity to a regulator corresponding to the target subharmonic current;
and the voltage conversion module is used for converting the target subharmonic current regulating quantity output by the regulator into a voltage quantity and then superposing the voltage quantity with a fundamental wave voltage to be used as a synthesized reference voltage output quantity so as to generate a compensation current for offsetting the target subharmonic current.
10. A computer-readable storage medium, characterized in that the computer-readable storage medium has stored thereon a converter circulating current control program, which when executed by a processor implements the steps of the method for controlling a multi-module direct parallel converter according to any of claims 1 to 7.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810594989.1A CN110581640B (en) | 2018-06-11 | 2018-06-11 | Control method and system of multi-module direct parallel converter and storage medium |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810594989.1A CN110581640B (en) | 2018-06-11 | 2018-06-11 | Control method and system of multi-module direct parallel converter and storage medium |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN110581640A CN110581640A (en) | 2019-12-17 |
| CN110581640B true CN110581640B (en) | 2021-06-08 |
Family
ID=68810130
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201810594989.1A Active CN110581640B (en) | 2018-06-11 | 2018-06-11 | Control method and system of multi-module direct parallel converter and storage medium |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN110581640B (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113517975B (en) * | 2021-09-13 | 2021-12-07 | 天津飞旋科技股份有限公司 | Carrier synchronization control method, system, converter device and readable storage medium |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103138543A (en) * | 2011-11-28 | 2013-06-05 | 中国北车股份有限公司大连电力牵引研发中心 | Control device and control method for four-quadrant converter |
| CN103915845A (en) * | 2014-04-11 | 2014-07-09 | 淮阴工学院 | Multilevel active power filter based on LCL filtering |
| CN107425545A (en) * | 2017-07-31 | 2017-12-01 | 上海交通大学 | The optimization modulator approach of volage current transformer in cascaded H-bridges |
| CN107546739A (en) * | 2016-06-29 | 2018-01-05 | 中车株洲电力机车研究所有限公司 | A kind of Electric Locomotive Harmonic administering method |
| CN107947544A (en) * | 2017-07-26 | 2018-04-20 | 贵州电网有限责任公司电力科学研究院 | A kind of unit cascaded type high-power high-frequency ice-melt power control method |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100557935C (en) * | 2007-09-28 | 2009-11-04 | 清华大学 | The single-phase unified electric energy quality controller that is used for electrified railway power supply |
-
2018
- 2018-06-11 CN CN201810594989.1A patent/CN110581640B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103138543A (en) * | 2011-11-28 | 2013-06-05 | 中国北车股份有限公司大连电力牵引研发中心 | Control device and control method for four-quadrant converter |
| CN103915845A (en) * | 2014-04-11 | 2014-07-09 | 淮阴工学院 | Multilevel active power filter based on LCL filtering |
| CN107546739A (en) * | 2016-06-29 | 2018-01-05 | 中车株洲电力机车研究所有限公司 | A kind of Electric Locomotive Harmonic administering method |
| CN107947544A (en) * | 2017-07-26 | 2018-04-20 | 贵州电网有限责任公司电力科学研究院 | A kind of unit cascaded type high-power high-frequency ice-melt power control method |
| CN107425545A (en) * | 2017-07-31 | 2017-12-01 | 上海交通大学 | The optimization modulator approach of volage current transformer in cascaded H-bridges |
Also Published As
| Publication number | Publication date |
|---|---|
| CN110581640A (en) | 2019-12-17 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Biricik et al. | Protection of sensitive loads using sliding mode controlled three-phase DVR with adaptive notch filter | |
| Liu et al. | Distributed generation using indirect matrix converter in reverse power mode | |
| US5283726A (en) | AC line current controller utilizing line connected inductance and DC voltage component | |
| Akagi et al. | Control and performance of a transformerless cascade PWM STATCOM with star configuration | |
| Wang et al. | An improved deadbeat control method for single-phase PWM rectifiers in charging system for EVs | |
| Zmood et al. | Improved voltage regulation for current-source inverters | |
| Aboelsaud et al. | Review of three-phase inverters control for unbalanced load compensation | |
| US6594164B2 (en) | PWM controlled power conversion device | |
| Mahato et al. | Modulation and control of multilevel inverter for an open‐end winding induction motor with constant voltage levels and harmonics | |
| US10541598B1 (en) | DC power generating system with voltage ripple compensation | |
| Wu et al. | Three-Phase Three-Wire Active Power Filter With D–$\Sigma $ Digital Control to Accommodate Filter-Inductance Variation | |
| Chebabhi et al. | A new balancing three level three dimensional space vector modulation strategy for three level neutral point clamped four leg inverter based shunt active power filter controlling by nonlinear back stepping controllers | |
| Mahato et al. | Constant V/f control and frequency control of isolated winding induction motor using nine-level three-phase inverter | |
| Patel et al. | Control of a stand-alone inverter-based distributed generation source for voltage regulation and harmonic compensation | |
| CN111293894B (en) | Capacitor voltage balance control method for modular multilevel matrix converter | |
| CN111133670B (en) | Controlling a voltage source converter in a DC system | |
| CN110581640B (en) | Control method and system of multi-module direct parallel converter and storage medium | |
| CN113904575A (en) | Precise pulse charge control type power supply system and control method thereof | |
| CN116054186A (en) | Hybrid multifunctional grid-connected converter system under complex scene and control method | |
| CN113517724B (en) | Method for suppressing voltage ripple on direct current side of alternating current-direct current hybrid micro-grid | |
| Behrouzian et al. | Individual capacitor voltage balancing in H-bridge cascaded multilevel STATCOM at zero current operating mode | |
| Wu et al. | Voltage source converter control under distorted grid voltage for hybrid ac-dc distribution links | |
| CN115413360A (en) | Power converter for photovoltaic energy sources | |
| Abbes et al. | Circulating current reduction of a grid-connected parallel interleaved converter using energy shaping control | |
| Gawande et al. | State feedback‐based capacitor voltage equalisation scheme in distribution static compensator for load compensation |
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 |