CN116054182A - Parallel hybrid active filter and control method of voltage dividing inductance terminal voltage thereof - Google Patents
Parallel hybrid active filter and control method of voltage dividing inductance terminal voltage thereof Download PDFInfo
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- CN116054182A CN116054182A CN202211398256.3A CN202211398256A CN116054182A CN 116054182 A CN116054182 A CN 116054182A CN 202211398256 A CN202211398256 A CN 202211398256A CN 116054182 A CN116054182 A CN 116054182A
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/18—Arrangements for adjusting, eliminating or compensating reactive power in networks
- H02J3/1821—Arrangements for adjusting, eliminating or compensating reactive power in networks using shunt compensators
- H02J3/1835—Arrangements for adjusting, eliminating or compensating reactive power in networks using shunt compensators with stepless control
- H02J3/1842—Arrangements for adjusting, eliminating or compensating reactive power in networks using shunt compensators with stepless control wherein at least one reactive element is actively controlled by a bridge converter, e.g. active filters
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/12—Circuit arrangements for ac mains or ac distribution networks for adjusting voltage in ac networks by changing a characteristic of the network load
- H02J3/16—Circuit arrangements for ac mains or ac distribution networks for adjusting voltage in ac networks by changing a characteristic of the network load by adjustment of reactive power
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- 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
- Y02E40/20—Active power filtering [APF]
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Abstract
The invention relates to the technical field of active power filters, in particular to a parallel hybrid active filter and a voltage dividing inductance terminal voltage control method thereof. Wherein: the direct current side of the converter is connected with the fourth capacitor in parallel, and the alternating current side of the converter is connected with the first three-phase circuit; each phase of the first three-phase circuit is respectively connected with a first inductor, a second inductor and a third inductor in series; the passive filter circuit comprises a second three-phase circuit; each phase of the second three-phase circuit is respectively connected with a fourth inductor, a first capacitor, a fifth inductor, a second capacitor, a sixth inductor and a third capacitor in series; the first three-phase circuit and the second three-phase circuit are connected in parallel according to corresponding phases; the modulating device is connected with the converter and controls the inductance voltage of the passive filter circuit by driving the converter; the invention can realize the control of the voltage dividing inductance end of the passive circuit by sending pulse drive to the converter through the modulation device, so that the DC side can obtain enough power flow, and further the harmonic wave treatment capability is improved.
Description
Technical Field
The invention relates to the technical field of active power filters, in particular to a parallel hybrid active filter and a voltage dividing inductance terminal voltage control method thereof.
Background
In recent years, with the wide application of resistive load and power electronic devices, the problem of harmonic pollution brought to daily life is more serious; the harmonic pollution not only can lead to local parallel resonance or series resonance of the power system, so that equipment such as a capacitor and the like is burnt out due to the amplification of harmonic content, but also can cause the problems of relay protection, misoperation of an automatic device, disordered electric energy metering and the like, and the problems are not in accordance with the requirement of improving the electric energy quality.
Active Power Filters (APFs) were first proposed in 1969, and after being proposed by the instantaneous reactive power theory, they are widely used, and are currently the most effective means for controlling harmonic pollution in the world. The method comprises the steps of sampling load current, separating subharmonic from reactive power, and controlling and actively outputting the magnitude, frequency and phase of the current to offset the corresponding harmonic current in the load; the dynamic tracking compensation is realized, the reactive power can be compensated while the harmonic wave is compensated, and the reliable operation of the power grid system is ensured.
The three main structural topological modes of the APF currently studied are as follows: the APF adopting the parallel topology is mainly applied to the situation that a harmonic load source is a current harmonic; the APF adopting the series topology is mainly applied to the situation that the harmonic load source is voltage harmonic; the APF adopting the mixed topology structure has the advantages of centralizing the two, improving the working performance of the common APF, but in the APF of the mixed topology, the voltage of the voltage dividing inductance end of the passive filtering part is uncontrollable, and the inductance of the passive filtering part has the voltage dividing function, so that the voltage of the alternating current side of the converter is reduced, the voltage difference of the alternating current side and the direct current side is overlarge, the control performance of the direct current side of the converter is influenced, and the harmonic treatment capability of the APF is reduced.
Disclosure of Invention
The invention provides a parallel hybrid active filter and a control method of voltage of a voltage dividing inductance end of the parallel hybrid active filter, and aims to solve the problem that the voltage of the inductance end of an APF passive filtering part is uncontrollable.
The first aspect of the present invention provides a parallel hybrid active filter comprising: an active filter circuit, a passive filter circuit and a modulation device;
the active filter circuit comprises a first three-phase circuit, a converter and a fourth capacitor;
the direct current side of the converter is connected with the fourth capacitor in parallel, and the alternating current side of the converter is connected with the first three-phase circuit;
each phase of the first three-phase circuit is respectively connected with a first inductor, a second inductor and a third inductor in series;
the passive filter circuit comprises a second three-phase circuit;
each phase of the second three-phase circuit is respectively connected with the fourth inductor, the first capacitor, the fifth inductor, the second capacitor, the sixth inductor and the third capacitor in series;
the first three-phase circuit is connected with the second three-phase circuit in parallel according to the corresponding phase;
the modulating device is connected with the current transformer and used for generating modulating waves, and the fourth inductor, the fifth inductor and the sixth inductor voltage are controlled through driving the current transformer.
Specifically, the modulation device includes: the device comprises a voltage acquisition module, a current acquisition module, a phase-locked loop, a first frequency component acquisition module, a second frequency component acquisition module, a first low-pass filter, a second low-pass filter, a first PI control module, a second PI control module, a direct-current voltage control module, a harmonic current control module and a pulse width modulation module;
the voltage acquisition module is respectively connected with the fourth capacitor, the fourth inductor, the fifth inductor, the sixth inductor and the second three-phase circuit and is used for acquiring voltages at two ends of the fourth capacitor, the fourth inductor, the fifth inductor and the sixth inductor and acquiring power grid voltages;
the current acquisition module is connected with the converter and the second three-phase circuit and is used for acquiring the output current of the converter and the power grid current;
the phase-locked loop is connected with the voltage acquisition module and is used for extracting a phase locking angle according to the power grid voltage acquired by the voltage acquisition module;
the voltage acquisition module is connected with the first frequency component acquisition module and is used for converting the voltages of the fourth inductor, the fifth inductor and the sixth inductor from a three-phase static coordinate system to a d-q synchronous rotation coordinate system through the first frequency component acquisition module;
the first frequency component acquisition module is connected with the first low-pass filter and is used for acquiring fundamental reactive components of the fourth inductor, the fifth inductor and the sixth inductor voltage through the first low-pass filter;
the first low-pass filter is connected with the first PI control module and is used for subtracting the fundamental reactive components of the fourth inductor, the fifth inductor and the sixth inductor from a preset reference value through the first PI control module and carrying out proportional integral adjustment to obtain current signals of the fourth inductor, the fifth inductor and the sixth inductor;
the converter is connected with the second frequency component acquisition module and is used for converting the three-phase current output by the converter from a three-phase static coordinate system to a d-q synchronous rotation coordinate system;
the second frequency component acquisition module is connected with the second low-pass filter and is used for acquiring a fundamental active component and a fundamental reactive component of the output current of the converter;
the second low-pass filter is connected with the second PI control module and is used for subtracting the current signals of the fourth inductor, the fifth inductor and the sixth inductor from the fundamental reactive component output by the converter through the second PI control module to generate a control quantity, and is also used for inversely transforming the control quantity to obtain the first modulation signal;
the voltage acquisition module, the second PI control module and the phase-locked loop are respectively connected with the direct-current voltage control module and are used for modulating the voltage at two ends of the fourth capacitor, the fundamental active component of the converter and the phase-locked angle to obtain a second modulation signal;
the harmonic current control module is connected with the current acquisition module and is used for modulating the acquired current to obtain a third modulation signal;
the pulse width modulation module is respectively connected with the converter, the second PI control module, the direct current voltage control module and the harmonic current control module, and is used for generating modulation waves through the first modulation signals, the second modulation signals and the third modulation signals and inputting the modulation waves into the converter, controlling the converter to generate driving pulses and controlling voltage of the split voltage sensing end.
Specifically, the modulating the voltage at two ends of the fourth capacitor, the fundamental active component of the converter and the phase-locked angle to obtain a second modulation signal specifically includes:
and the voltage at the two ends of the fourth capacitor is obtained through preset value adjustment, is subtracted from the fundamental wave active component output by the converter after proportional integral adjustment, the difference value is subjected to proportional integral adjustment to obtain an adjustment signal of the voltage at the two ends of the fourth capacitor, and then the adjustment signal is subjected to inverse transformation according to a phase-locked angle to obtain a second modulation signal.
Specifically, the modulating the collected current to obtain a third modulation signal specifically includes:
and synchronously rotating the obtained grid current and the angular speed of a certain designated subharmonic to obtain the direct current of the designated subharmonic, and performing proportional integral adjustment on the direct current of the designated subharmonic and then performing inverse transformation to obtain a third modulation signal.
Specifically, first parasitic resistances with the same size are generated among the first inductor, the second inductor, the third inductor and the converter;
the low potential sides of the fourth, fifth and sixth inductors all generate second parasitic resistances of equal magnitude.
Specifically, each phase of the first three-phase circuit is connected in parallel between the fourth inductor and the fourth capacitor, the fifth inductor and the second capacitor, and the sixth inductor and the third capacitor of the corresponding phase of the second three-phase circuit.
On the other hand, the invention provides a control method for the voltage of the voltage dividing inductance end of the parallel hybrid active filter, which comprises the following steps:
s1: acquiring power grid voltage and power grid current, three-phase voltage of a passive circuit inductor, three-phase current output by a converter and voltages at two ends of an active circuit capacitor;
s2: extracting a lock phase angle according to the power grid voltage;
s3: transforming the voltage of the passive circuit inductor from a three-phase static coordinate system to a d-q synchronous rotation coordinate system through the phase locking angle of the power grid voltage, and performing low-pass filtering to obtain a fundamental reactive component of the passive circuit inductor voltage;
s4: subtracting a preset reference value of the fundamental reactive component of the inductance voltage of the passive circuit from the fundamental reactive component of the inductance voltage, and performing proportional integral adjustment to obtain a current signal of the passive circuit inductance;
s5: according to the phase locking angle of the power grid voltage, transforming the three-phase current output by the converter from a three-phase static coordinate system to a d-q synchronous rotation coordinate system, and performing low-pass filtering to obtain a fundamental active component and a fundamental reactive component of the current output by the converter;
s6: the current signal of the passive circuit inductor and the fundamental wave reactive component output by the converter are subtracted to generate a control quantity through proportional integral regulation;
s7: according to the phase-locked angle of the power grid voltage, reversely converting the control quantity to obtain a first modulation signal;
s8: subtracting the voltage at two ends of the active circuit capacitor from a preset reference value to obtain a voltage adjustment value, subtracting the voltage adjustment value from a fundamental reactive component output by the converter after proportional integral adjustment, and then carrying out proportional integral adjustment on the difference value again to obtain an adjustment signal of the voltage at two ends of the capacitor;
s9: according to the phase locking angle of the power grid voltage, the adjusting signals of the voltages at the two ends of the capacitor are inversely transformed to obtain a second modulating signal;
s10: the method comprises the steps of adopting a designated subharmonic current control strategy based on a multi-synchronous rotation coordinate system, synchronously rotating the obtained output current of the parallel hybrid active filter and the angular speed of the designated subharmonic to obtain the direct current of the designated subharmonic, and performing proportional integral adjustment and inverse transformation on the direct current of the designated subharmonic to obtain a third modulation signal;
s11: and adding the first modulation signal, the second modulation signal and the third modulation signal to obtain a modulation wave, inputting the modulation wave into a current transformer to generate driving pulse, and controlling the voltage of the passive circuit inductor.
Specifically, the designated subharmonic is any subharmonic of 5 subharmonic, 7 subharmonic, 11 subharmonic and 13 subharmonic.
Specifically, the low-pass filtering frequency is less than 2 times of the fundamental frequency of the power grid.
Specifically, the preset reference value of the fundamental reactive component of the inductance voltage is larger than the fundamental reactive component of the inductance voltage of the passive circuit.
The invention has the beneficial effects that: the embodiment of the invention provides a parallel hybrid active filter, which comprises: the fourth capacitor, the converter, the first three-phase circuit, the second three-phase circuit and the modulation device; the fourth capacitor is connected with the converter in parallel; the converter is connected with the first three-phase circuit in series; each phase of the first three-phase circuit is connected with a first inductor, a second inductor and a third inductor in series, and the first inductor, the second inductor and the third inductor, a fourth capacitor and a converter form an active filter circuit together; each phase of the second three-phase circuit is connected with a fourth inductor, a fifth inductor, a sixth inductor, a first capacitor, a second capacitor and a third capacitor in series to form a passive filter circuit; each phase of the first three-phase circuit and the second three-phase circuit are connected in parallel; the modulating device is connected with the current transformer and is used for generating modulating waves and driving the current transformer to output pulses for controlling the fourth inductance, the fifth inductance and the sixth inductance voltage;
according to the parallel hybrid active filter provided by the embodiment of the invention, the control of the voltage dividing inductance end of the passive circuit can be realized by sending pulse drive to the converter through the modulation device, so that the voltage difference between the alternating current side and the direct current side of the converter is effectively shortened, the direct current side can obtain enough power flow, and the harmonic treatment capability of the parallel hybrid active filter is further improved.
Drawings
In order to more clearly illustrate the embodiments of the invention or the technical solutions of the prior art, the drawings which are used in the description of the embodiments or the prior art will be briefly described, it being obvious that the drawings in the description below are only some embodiments of the invention, and that other drawings can be obtained according to these drawings without inventive faculty for a person skilled in the art.
FIG. 1 is a main circuit topology of a parallel hybrid active power filter;
FIG. 2 is a diagram of DC component simulation control of the inductor voltage;
FIG. 3 is a simulated waveform of three-phase voltages under control of inductor voltage;
FIG. 4 is a waveform diagram of grid voltage and grid current after harmonic remediation;
FIG. 5 is a waveform diagram of the current distortion of the grid after harmonic suppression;
FIG. 6 is a schematic diagram of a modulation device;
FIG. 7 is a block diagram of the structure of the current transformer and the inductor voltage in the d-q coordinate system;
fig. 8 is a system control block diagram.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are only some, but not all embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
In a first aspect of the present invention, referring to fig. 1, fig. 1 is a main circuit topology diagram of a parallel hybrid active power filter.
The parallel hybrid active filter includes: an active filter circuit, a passive filter circuit and a modulation device;
wherein: the active filter circuit comprises a fourth capacitor C', a converter and a first three-phase circuit;
the direct current side of the converter is connected with the fourth capacitor C' in parallel, and the alternating current side of the converter is connected with the first three-phase circuit;
the first three-phase circuit comprises three branches a, b and c corresponding to the three-phase circuit;
the branch a, the branch b and the branch c are respectively connected with a first inductor L in series fa Second inductance L fb And a third inductance L fc ；
The passive filter circuit comprises a second three-phase circuit;
the second three-phase circuit comprises three branches a corresponding to the three-phase circuit 1 、b 1 、c 1 ；
Branch a 1 A fourth inductor L is connected in series with a And a fourth capacitance C', branch a 2 A fifth inductor L is connected in series with b And a second capacitor C b Branch a 3 A sixth inductor L is connected in series with c And a third capacitor C c ；
A 1 For branch a and branch a 1 Is a connecting point of B 1 For branch b and branch b 1 C of the connection point of (C) 1 For branch c and branch c 1 Is a connection point of (2);
the modulating device is connected with the current transformer and is used for generating a modulating wave according to a preset modulating signal, sending the modulating wave to the current transformer and driving the current transformer to adjust the fourth inductance L according to the modulating wave a Fifth inductance L b Sixth inductance L c Voltage at the terminal.
In a specific implementation process, in order to more intuitively represent the relationship between the output voltage and the inductance voltage of the current transformer, a mathematical model applied to the parallel hybrid active power filter shown in fig. 1 may be established;
it can be understood that, because the circuit is a three-phase symmetrical circuit, only one phase is selected, and a mathematical model is established as follows:
i ca ＝i fa -i La (4)
wherein: i.e fa Output current of one phase of the converter, u fa Output voltage corresponding to one phase of the converter, u sa For the network voltage of a corresponding phase, u La To correspond to one-phase inductance voltage, i La For the inductive current of a corresponding phase, i Ca For injection current corresponding to a phase;
it will be appreciated that the inductance of the active circuit corresponding to one phase is the same as the inductance of the passive circuit corresponding to one phase, and therefore both are denoted by L, and the parasitic resistances R1 and R2 are the same, and therefore both are denoted by R;
the equations (1), (2), (3) and (4) can be converted and deduced:
since the three phases are symmetrical, the relationship of A, B, C three phases can be obtained by the same method, and is organized as follows:
establishing a mathematical model under a d-q synchronous rotation coordinate system according to the mathematical model under the static coordinate system;
in the implementation process, it is found that the voltage dividing inductor terminal voltage and the power grid voltage u sa 、u sb 、u sc Fourth inductance L a Fifth inductance L b Sixth inductance L c Is provided, the output current i of the converter fa 、i fb 、i fc The voltages at the two ends of the fourth capacitor C' are directly or indirectly related, so that the voltage of the voltage division inductance end can be controlled by collecting the data, performing modeling preview in software in a MATLAB or Simulink simulation mode and inputting the modulation wave of the converter through an analog modulation device.
Fig. 2 and 3 are respectively a simulation control diagram of the dc component of the inductance voltage and a simulation waveform diagram of the three-phase voltage under the control of the inductance voltage.
After the simulation circuit of the system is built and the system is operated, the control effect of the direct current component of the inductance voltage and the waveform of the inductance three-phase voltage when the inductance voltage is controlled are shown as the figure.
FIG. 4 is a waveform diagram of grid voltage and grid current after harmonic remediation using a parallel hybrid active power filter; FIG. 5 is a waveform diagram of the grid current distortion rate after using a parallel hybrid active power filter;
the voltage stabilizing effect of the direct current side of the converter is better when the inductance voltage control link is added, the harmonic compensation capability is obviously improved, and the current quality is obviously improved.
In another embodiment of the present invention, as shown in fig. 6, the modulation apparatus specifically includes: the device comprises a voltage acquisition module, a current acquisition module, a phase-locked loop, a first frequency component acquisition module, a second frequency component acquisition module, a first low-pass filter, a second low-pass filter, a first PI control module, a second PI control module, a direct-current voltage control module, a harmonic current control module and a pulse width modulation module;
the voltage acquisition module is respectively connected with the fourth capacitor C 'and the first capacitor C', respectivelyFour inductances L fa Fifth inductance L fb Sixth inductance L fc A second three-phase circuit connected to collect a fourth capacitor C' and a fourth inductance L fa Fifth inductance L fb Sixth inductance L fc The voltage of two ends and collecting the voltage of a power grid;
the current acquisition module is connected with the converter and the second three-phase circuit and is used for acquiring the output current of the converter and the current of the power grid;
the phase-locked loop is connected with the voltage acquisition module and is used for extracting a phase locking angle according to the power grid voltage acquired by the voltage acquisition module;
the voltage acquisition module is connected with the first frequency component acquisition module and is used for acquiring the fourth inductance L through the first frequency component acquisition module a Fifth inductance L b Sixth inductance L c The voltage of the (b) is converted from a three-phase static coordinate system to a d-q synchronous rotating coordinate system;
the first frequency component acquisition module is connected with the first low-pass filter and is used for acquiring a fourth inductance L through the first low-pass filter a Fifth inductance L b Sixth inductance L c A fundamental reactive component of the voltage;
the first low-pass filter is connected with the first PI control module and is used for connecting the fourth inductor L through the first PI control module a Fifth inductance L b Sixth inductance L c The fundamental reactive component of the voltage is subtracted from a preset reference value, and proportional integral adjustment is carried out to obtain a fourth inductance L a Fifth inductance L b Sixth inductance L c Is a current signal of (a);
the converter is connected with the second frequency component acquisition module and is used for converting the three-phase current output by the converter from a three-phase static coordinate system to a d-q synchronous rotation coordinate system;
the second frequency component acquisition module is connected with the second low-pass filter and is used for acquiring a fundamental active component and a fundamental reactive component of the output current of the converter;
the second low-pass filter is connected with the second PI control module and is used for subtracting the fundamental reactive components output by the converter from the current signals of the fourth inductor, the fifth inductor and the sixth inductor through the second PI control module to generate control quantities and inversely transforming the control quantities to obtain first modulation signals;
the voltage acquisition module, the second PI control module and the phase-locked loop are respectively connected with the direct-current voltage control module and are used for modulating the voltage at two ends of the fourth capacitor C', the fundamental active component of the converter and the phase-locked angle to obtain a second modulation signal;
the harmonic current control module is connected with the current acquisition module and used for modulating the acquired current to obtain a third modulation signal;
the pulse width modulation module is respectively connected with the converter, the second PI control module, the direct current voltage control module and the harmonic current control module and is used for generating modulation waves through the first modulation signal, the second modulation signal and the third modulation signal and inputting the modulation waves into the converter, controlling the converter to generate driving pulses and controlling the voltage of the split piezoelectric sensing terminal.
In another more specific embodiment of the present invention, the voltage at two ends of the fourth capacitor C 'is obtained by adjusting a preset value, the voltage is subtracted from the fundamental wave active component output by the converter after proportional integral adjustment, the difference value is subjected to proportional integral adjustment to obtain an adjustment signal of the voltage at two ends of the fourth capacitor C', and then the adjustment signal is subjected to inverse transformation according to the phase-locked angle to obtain the second modulation signal.
In another more specific embodiment of the present invention, the obtained grid current and the angular velocity of a specific subharmonic are synchronously rotated to obtain the direct current of the specific subharmonic, and the direct current of the specific subharmonic is subjected to proportional integral adjustment and then is subjected to inverse transformation, so as to obtain the third modulation signal.
In another embodiment of the present invention, a first parasitic resistance R of equal magnitude is generated between the inductor and the current transformer on each branch of the first three-phase circuit 1 。
In another embodiment of the present invention, in the fourth inductance L a Fifth inductance L b Sixth inductance L c Is provided with second parasitic electric power with equal magnitudeR resistance 2 。
In another embodiment of the present invention, three branches a of the passive filter circuit 1 、b 1 、c 1 Three-phase circuits respectively corresponding to the power grid are connected with A 2 、B 2 、C 2 And (5) a dot.
As shown in fig. 7 and 8, the present invention further provides a parallel hybrid active filter and a method for controlling a voltage across a divided inductor thereof, which includes the following steps:
s1: collecting three-phase voltage u of power grid sa 、u sb 、u sc Obtaining a phase-locked angle theta of the power grid voltage through a phase-locking link;
s2: in the passive filtering part, the voltage u of each branch inductance L is collected La 、u Lb 、u Lc The voltage u of the inductance L is calculated according to the phase locking angle theta La 、u Lb 、u Lc Transforming from a three-phase static coordinate system to a d-q synchronous rotation coordinate system, and performing low-pass filtering with fundamental frequency lower than 2 times of the power grid fundamental frequency to obtain fundamental reactive component u of inductance L voltage Lq The formula is as follows:
s3: presetting a reference value for the fundamental reactive component of the inductance L voltage, and obtaining the fundamental reactive component u of the inductance L voltage Lq Subtracting a preset reference value to generate deviation, and regulating the deviation through proportional integral to obtain a current signal i of the inductor L Lq * ；
It should be noted that the reference value of the fundamental reactive component of the preset inductance L voltage is larger than the fundamental reactive component u Lq ；
S4: respectively collecting output currents i of the converters fa 、i fb 、i fc I is calculated according to the phase locking angle theta fa 、i fb 、i fc After being transformed into a d-q coordinate system, the converter carries out low-pass filtering with the fundamental frequency of the power grid lower than 2 times to obtain the fundamental active component i of the output current of the converter fd And a fundamental reactive component i fq The formula is as follows;
s5: the current signal i of the inductor L is regulated by proportional integral Lq * And a fundamental reactive component i of the converter output current fq Subtracting the generated control amount to generate a control amount u q ；
S6: according to the phase-locked angle theta of the power grid voltage, the control quantity u is calculated q Inverse transformation to obtain a first modulated signal U α And U β The formula is as follows:
s7: setting a reference value for the voltage at two ends of the capacitor C', and collecting the voltage U at two ends of the capacitor C dc’ Subtracting the reference value of the voltage at two ends of the capacitor C 'from the reference value of the voltage at two ends of the capacitor C', and regulating the reference value by proportional integral and then regulating the reference value with the fundamental wave active component i of the current of the converter fd Subtracting, proportional-integral regulating the difference to obtain a voltage signal U dc’ *；
It should be noted that, the reference value of the voltage at two ends of the capacitor C' is the standard value in the ideal operation condition;
s8: according to the phase locking angle theta, to U dc’ * Performing inverse transformation to obtain a second modulation signal U α1 And U β1 The formula is as follows:
s9: collecting power grid current, adopting a designated subharmonic current control strategy based on a multi-synchronous rotation coordinate system, synchronously rotating the obtained power grid current and the angular speed of a designated subharmonic to obtain the direct current of the designated subharmonic, performing proportional integral adjustment on the direct current of the designated subharmonic, and then performing inverse transformation to obtain a third modulation signal U αn And U βn ；
The designated subharmonic is any subharmonic of 5 subharmonic, 7 subharmonic, 11 subharmonic, and 13 subharmonic;
s10: and adding the first, second and third modulation signals to obtain a modulation wave for controlling the voltage of the voltage division inductance end, and further generating driving pulse of the converter by the modulation wave to control the voltage of the voltage division inductance end.
In another embodiment of the present invention, the control amount u may be controlled by a feed-forward decoupling method q Subtracting the decoupling component of the q-axis to further increase the control amount u q Is a function of the accuracy of the (c).
The terms "first," "second," "third," "fourth," and the like in the description of the present application and in the above-described figures, if any, are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used may be interchanged where appropriate such that embodiments of the present application described herein may be capable of operation in sequences other than those illustrated or described herein, for example. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.
It should be understood that in this application, "at least one" means one or more, and "a plurality" means two or more. "and/or" for describing the association relationship of the association object, the representation may have three relationships, for example, "a and/or B" may represent: only a, only B and both a and B are present, wherein a, B may be singular or plural. The character "/" generally indicates that the context-dependent object is an "or" relationship. "at least one of" or the like means any combination of these items, including any combination of single item(s) or plural items(s). For example, at least one (one) of a, b or c may represent: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", wherein a, b, c may be single or plural.
In the several embodiments provided in this application, it should be understood that the disclosed apparatus and method may be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative, e.g., the division of the units is merely a logical function division, and there may be additional divisions when actually implemented, e.g., multiple units or components may be combined or integrated into another system, or some features may be omitted or not performed. Alternatively, the coupling or direct coupling or communication connection shown or discussed with each other may be an indirect coupling or communication connection via some interfaces, devices or units, which may be in electrical, mechanical or other form.
The units described as separate units may or may not be physically separate, and units shown as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.
In addition, each functional unit in each embodiment of the present application may be integrated in one processing unit, or each unit may exist alone physically, or two or more units may be integrated in one unit. The integrated units may be implemented in hardware or in software functional units.
The above embodiments are merely for illustrating the technical solution of the present application, and not for limiting the same; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the corresponding technical solutions.
Claims (10)
1. A parallel hybrid active filter, comprising: an active filter circuit, a passive filter circuit and a modulation device;
the active filter circuit comprises a first three-phase circuit, a converter and a fourth capacitor;
the direct current side of the converter is connected with the fourth capacitor in parallel, and the alternating current side of the converter is connected with the first three-phase circuit;
each phase of the first three-phase circuit is respectively connected with a first inductor, a second inductor and a third inductor in series;
the passive filter circuit comprises a second three-phase circuit;
each phase of the second three-phase circuit is respectively connected with the fourth inductor, the first capacitor, the fifth inductor, the second capacitor, the sixth inductor and the third capacitor in series;
the first three-phase circuit is connected with the second three-phase circuit in parallel according to the corresponding phase;
the modulating device is connected with the current transformer and used for generating modulating waves, and the fourth inductor, the fifth inductor and the sixth inductor voltage are controlled through driving the current transformer.
2. A parallel hybrid active filter according to claim 1, wherein the modulating means comprises: the device comprises a voltage acquisition module, a current acquisition module, a phase-locked loop, a first frequency component acquisition module, a second frequency component acquisition module, a first low-pass filter, a second low-pass filter, a first PI control module, a second PI control module, a direct-current voltage control module, a harmonic current control module and a pulse width modulation module;
the voltage acquisition module is respectively connected with the fourth capacitor, the fourth inductor, the fifth inductor, the sixth inductor and the second three-phase circuit and is used for acquiring voltages at two ends of the fourth capacitor, the fourth inductor, the fifth inductor and the sixth inductor and acquiring power grid voltages;
the current acquisition module is connected with the converter and the second three-phase circuit and is used for acquiring the output current of the converter and the power grid current;
the phase-locked loop is connected with the voltage acquisition module and is used for extracting a phase locking angle according to the power grid voltage acquired by the voltage acquisition module;
the voltage acquisition module is connected with the first frequency component acquisition module and is used for converting the voltages of the fourth inductor, the fifth inductor and the sixth inductor from a three-phase static coordinate system to a d-q synchronous rotation coordinate system through the first frequency component acquisition module;
the first frequency component acquisition module is connected with the first low-pass filter and is used for acquiring fundamental reactive components of the fourth inductor, the fifth inductor and the sixth inductor voltage through the first low-pass filter;
the first low-pass filter is connected with the first PI control module and is used for subtracting the fundamental reactive components of the fourth inductor, the fifth inductor and the sixth inductor from a preset reference value through the first PI control module and carrying out proportional integral adjustment to obtain current signals of the fourth inductor, the fifth inductor and the sixth inductor;
the converter is connected with the second frequency component acquisition module and is used for converting the three-phase current output by the converter from a three-phase static coordinate system to a d-q synchronous rotation coordinate system;
the second frequency component acquisition module is connected with the second low-pass filter and is used for acquiring a fundamental active component and a fundamental reactive component output by the converter;
the second low-pass filter is connected with the second PI control module and is used for subtracting the current signals of the fourth inductor, the fifth inductor and the sixth inductor from the fundamental reactive component output by the converter through the second PI control module to generate a control quantity, and is also used for inversely transforming the control quantity to obtain the first modulation signal;
the voltage acquisition module, the second PI control module and the phase-locked loop are respectively connected with the direct-current voltage control module and are used for modulating the voltage at two ends of the fourth capacitor, the fundamental active component of the converter and the phase-locked angle to obtain a second modulation signal;
the harmonic current control module is connected with the current acquisition module and is used for modulating the acquired current to obtain a third modulation signal;
the pulse width modulation module is respectively connected with the converter, the second PI control module, the direct current voltage control module and the harmonic current control module, and is used for generating modulation waves through the first modulation signals, the second modulation signals and the third modulation signals and inputting the modulation waves into the converter, controlling the converter to generate driving pulses and controlling voltage of the split voltage sensing end.
3. The parallel hybrid active filter according to claim 2, wherein the modulating the voltage across the fourth capacitor, the fundamental active component of the converter, and the phase-locked angle obtains a second modulated signal, specifically:
and the voltage at the two ends of the fourth capacitor is obtained through preset value adjustment, is subtracted from the fundamental wave active component output by the converter after proportional integral adjustment, the difference value is subjected to proportional integral adjustment to obtain an adjustment signal of the voltage at the two ends of the fourth capacitor, and then the adjustment signal is subjected to inverse transformation according to a phase-locked angle to obtain a second modulation signal.
4. The parallel hybrid active filter according to claim 2, wherein the modulating the collected current to obtain a third modulated signal is specifically:
and synchronously rotating the obtained grid current and the angular speed of a certain designated subharmonic to obtain the direct current of the designated subharmonic, and performing proportional integral adjustment on the direct current of the designated subharmonic and then performing inverse transformation to obtain a third modulation signal.
5. The parallel hybrid active filter of claim 1, wherein the first inductor, the second inductor, the third inductor and the current transformer each produce first parasitic resistances of equal magnitude;
the low potential sides of the fourth, fifth and sixth inductors all generate second parasitic resistances of equal magnitude.
6. The parallel hybrid active filter of claim 1, wherein each phase of the first three-phase circuit is connected in parallel between the fourth inductor and the fourth capacitor, the fifth inductor and the second capacitor, and the sixth inductor and the third capacitor of a corresponding phase of the second three-phase circuit.
7. A parallel hybrid active filter and a control method of voltage of a divided inductor terminal thereof, which are applied to the parallel hybrid active filter as claimed in claims 1-6, and are characterized by comprising the following steps:
s1: acquiring power grid voltage and power grid current, three-phase voltage of a passive circuit inductor, three-phase current output by a converter and voltages at two ends of an active circuit capacitor;
s2: extracting a lock phase angle according to the power grid voltage;
s3: transforming the voltage of the passive circuit inductor from a three-phase static coordinate system to a d-q synchronous rotation coordinate system through the phase locking angle of the power grid voltage, and performing low-pass filtering to obtain a fundamental reactive component of the passive circuit inductor voltage;
s4: subtracting a preset reference value of the fundamental reactive component of the inductance voltage of the passive circuit from the fundamental reactive component of the inductance voltage, and performing proportional integral adjustment to obtain a current signal of the passive circuit inductance;
s5: according to the phase locking angle of the power grid voltage, transforming the three-phase current output by the converter from a three-phase static coordinate system to a d-q synchronous rotation coordinate system, and performing low-pass filtering to obtain a fundamental active component and a fundamental reactive component of the current output by the converter;
s6: the current signal of the passive circuit inductor and the fundamental wave reactive component output by the converter are subtracted to generate a control quantity through proportional integral regulation;
s7: according to the phase-locked angle of the power grid voltage, reversely converting the control quantity to obtain a first modulation signal;
s8: subtracting the voltage at two ends of the active circuit capacitor from a preset reference value to obtain a voltage adjustment value, subtracting the voltage adjustment value from a fundamental reactive component output by the converter after proportional integral adjustment, and then carrying out proportional integral adjustment on the difference value again to obtain an adjustment signal of the voltage at two ends of the capacitor;
s9: according to the phase locking angle of the power grid voltage, the adjusting signals of the voltages at the two ends of the capacitor are inversely transformed to obtain a second modulating signal;
s10: the method comprises the steps of adopting a designated subharmonic current control strategy based on a multi-synchronous rotation coordinate system, synchronously rotating the obtained output current of the parallel hybrid active filter and the angular speed of the designated subharmonic to obtain the direct current of the designated subharmonic, and performing proportional integral adjustment and inverse transformation on the direct current of the designated subharmonic to obtain a third modulation signal;
s11: and adding the first modulation signal, the second modulation signal and the third modulation signal to obtain a modulation wave, inputting the modulation wave into a current transformer to generate driving pulse, and controlling the voltage of the passive circuit inductor.
8. The parallel hybrid active filter and the method for controlling the voltage across the divided inductor according to claim 7, wherein the predetermined harmonic is any one of 5 th harmonic, 7 th harmonic, 11 th harmonic, and 13 th harmonic.
9. The parallel hybrid active filter and the method for controlling the voltage across the divided inductor of the parallel hybrid active filter according to claim 7, wherein the low pass filtering frequency is less than 2 times the fundamental frequency of the power grid.
10. The parallel hybrid active filter and the method for controlling the divided inductor terminal voltage thereof according to claim 7, wherein the preset reference value of the fundamental reactive component of the inductor voltage is greater than the fundamental reactive component of the inductor voltage of the passive circuit.
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