CN113991672A - Distributed control system and method based on three-level bidirectional current transformation - Google Patents

Distributed control system and method based on three-level bidirectional current transformation Download PDF

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CN113991672A
CN113991672A CN202111242529.0A CN202111242529A CN113991672A CN 113991672 A CN113991672 A CN 113991672A CN 202111242529 A CN202111242529 A CN 202111242529A CN 113991672 A CN113991672 A CN 113991672A
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current
phase
level bidirectional
instantaneous
voltage
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CN113991672B (en
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彭博
曹家伟
李延真
朱晓东
郑准
郭英雷
牟磊
周君
李晓悦
孙晓兰
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QINGDAO POWER SUPPLY Co OF STATE GRID SHANDONG ELECTRIC POWER Co
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QINGDAO POWER SUPPLY Co OF STATE GRID SHANDONG ELECTRIC POWER Co
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/01—Arrangements for reducing harmonics or ripples
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/18—Arrangements for adjusting, eliminating or compensating reactive power in networks
    • 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
    • H02J3/1807—Arrangements for adjusting, eliminating or compensating reactive power in networks using series compensators
    • H02J3/1814—Arrangements for adjusting, eliminating or compensating reactive power in networks using series compensators wherein al least one reactive element is actively controlled by a bridge converter, e.g. unified power flow controllers [UPFC]
    • 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
    • H02J3/28—Arrangements for balancing of the load in a network by storage of energy
    • 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
    • H02J3/28—Arrangements for balancing of the load in a network by storage of energy
    • H02J3/32—Arrangements for balancing of the load in a network by storage of energy using batteries with converting means
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/66—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output with possibility of reversal
    • H02M7/68—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output with possibility of reversal by static converters
    • H02M7/72—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output with possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/79—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output with possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M7/797—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output with possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
    • 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
    • Y02E40/30—Reactive power compensation
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
    • Y02E40/40—Arrangements for reducing harmonics

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Inverter Devices (AREA)
  • Control Of Electrical Variables (AREA)

Abstract

The utility model provides a distributed control system and method based on three-level bidirectional current transformation, comprising a main circuit and a control circuit; the main circuit comprises a low-pass filter, a direct-current filter, a three-level bidirectional converter, a PWM converter and a driving and protecting circuit; the control circuit comprises a control regulator and a current tracking control circuit; the three-level bidirectional converter obtains fundamental wave positive sequence current components of instantaneous active current components and instantaneous reactive current components from the collected three-phase load side through coordinate transformation and a low-pass filter, and bases the whole sequence of three-phase currentThe wave component becomes a direct current; i based on instantaneous voltage vector orientationp‑iqAnd (5) obtaining the compensation command current by a detection method, and finishing the processing of the current fundamental component.

Description

Distributed control system and method based on three-level bidirectional current transformation
Technical Field
The disclosure belongs to the technical field of bidirectional conversion, and particularly relates to a distributed control system and method based on three-level bidirectional conversion.
Background
The statements in this section merely provide background information related to the present disclosure and may not necessarily constitute prior art.
The bidirectional converter is an important component in a distributed energy storage system and is a converter device for realizing mutual conversion of direct current electric energy and alternating current electric energy. The bidirectional converter is divided into a voltage type bidirectional converter and a current type bidirectional converter according to different direct current side energy storage devices. The most prominent characteristic of the voltage type bidirectional converter is that a direct current side capacitor is used as an energy storage element, so that the whole system presents the characteristic of a low-impedance voltage source, and the most prominent characteristic of the current type bidirectional converter is that a direct current side inductor is used as an energy storage element, so that the whole system presents high impedance.
The current type bidirectional converter is large in size and complex in main circuit structure, and diodes need to be connected in series on a power switch loop, so that the topological structure of the current type bidirectional converter is more complex, and the voltage type bidirectional converter is wider in actual application at present. The voltage type bidirectional converter can be divided into a two-level bidirectional converter, a three-level bidirectional converter and a multi-level bidirectional converter according to different output voltage structures. The two-level bidirectional converter has a simple main circuit topological structure and a relatively mature control strategy, but needs to be matched with a heavy transformer for use. In order to obtain a good output waveform, the switching frequency needs to be increased, which results in high switching loss.
NabaeA in 1981 proposes a topological structure of a three-level bidirectional converter and proposes the idea of a multi-level converter, namely that synthesized step waves approximate sine wave output voltages from several steps. The three-level bidirectional converter can reduce the loss of a switching device, reduce the switching frequency and reduce the generated harmonic wave; the three-level bidirectional converter has the advantages that the service life is prolonged, the change between adjacent levels is relatively reduced due to the fact that the number of output levels is increased, and the three-level bidirectional converter is widely applied to a distributed energy storage system.
As far as the inventors are aware, in terms of bidirectional converter control strategies, indirect current control strategies and direct current control strategies are mainly employed. The indirect current control is to indirectly control the network side current of the voltage type bidirectional converter by controlling the amplitude and the phase of the fundamental wave of the alternating-current side voltage; however, the dynamic response of the network side current controlled by indirect current is slow, and the system parameter change is sensitive; the direct current control has higher response speed and control precision, is not influenced by parameter coefficients, and has good robustness; direct current control strategies are common.
In the reactive compensation and harmonic treatment processes, aiming at a direct current control strategy in a three-level bidirectional converter, how to process a current fundamental component is the key for realizing distributed control based on three-level bidirectional conversion.
Disclosure of Invention
In order to solve the problems, the present disclosure provides a distributed control system and method based on three-level bidirectional conversion, which designs an Active Power Filter (APF) device based on reactive compensation and harmonic suppression, processes the current fundamental component in the reactive compensation and harmonic suppression, obtains the fundamental positive sequence current component of the instantaneous active current component and the instantaneous reactive current component on the collected three-phase load side through coordinate transformation and a low-pass filter, and changes the integral sequence fundamental component of the three-phase current into a direct current component through transformation to obtain a compensation command current; the problem of unbalanced midpoint potential of the three-level bidirectional converter is solved, and the running reliability of the distributed energy storage system is improved.
According to some embodiments, a first aspect of the present disclosure provides a distributed control system based on three-level bidirectional variable current, which adopts the following technical solutions:
a distributed control system based on three-level bidirectional variable current comprises a main circuit and a control circuit; the main circuit comprises a low-pass filter, a direct-current filter, a three-level bidirectional converter, a PWM converter and a driving and protecting circuit; the control circuit comprises a control regulator and a current tracking control circuit;
the three-level bidirectional converter obtains fundamental wave positive sequence current components of instantaneous active current components and instantaneous reactive current components from the collected three-phase load side through coordinate transformation and a low-pass filter, and converts the whole sequence fundamental wave components of three-phase current into direct current; i based on instantaneous voltage vector orientationp-iqAnd (5) obtaining the compensation command current by a detection method, and finishing the processing of the current fundamental component.
According to some embodiments, a second aspect of the present disclosure provides a distributed control method based on three-level bidirectional conversion.
A distributed control method based on three-level bidirectional variable flow comprises the following steps:
the three-level bidirectional converter collects three-phase load instantaneous current;
coordinate transformation and low-pass filtering are carried out on the obtained three-phase load instantaneous current, and the integral fundamental current component of the instantaneous active current component and the instantaneous reactive current component in the three-phase load instantaneous current are respectively obtained;
according to i oriented based on instantaneous voltage vectorp-iqAnd calculating the positive sequence current component of the three-phase current by using a detection method to obtain a compensation command current, and finishing the processing of the current fundamental component. .
Compared with the prior art, the beneficial effect of this disclosure is:
according to the method, the influence of the upper and lower direct states on the voltages of two voltage-dividing capacitors is analyzed through the improvement of the midpoint potential offset based on the direct offset, the feedback of the voltage-dividing capacitors is added to adjust the upper and lower direct time, the voltage-sharing adjustment control of the voltage-dividing capacitors is tested, the low-frequency oscillation of the midpoint potential is restrained, the problem of the unbalanced midpoint potential of the three-level bidirectional converter is further improved, and the operation reliability of the distributed energy storage system is improved.
Drawings
The accompanying drawings, which are included to provide a further understanding of the disclosure, illustrate embodiments of the disclosure and together with the description serve to explain the disclosure and are not to limit the disclosure.
Fig. 1 is a schematic diagram of a distributed control system based on three-level bidirectional conversion in a first embodiment of the present disclosure;
fig. 2 is a main circuit diagram of a three-level bidirectional converter in the first embodiment of the disclosure;
fig. 3 is an equivalent circuit diagram of a three-level bidirectional converter in the first embodiment of the disclosure;
fig. 4 is a voltage space vector diagram of a three-level bidirectional converter in accordance with an embodiment of the present disclosure;
FIG. 5 is a schematic diagram of coordinate transformation in a second embodiment of the disclosure;
FIG. 6 shows an example of an instantaneous voltage vector orientation-based i in an embodiment II of the present disclosurep-iqA flow chart of the detection method;
FIG. 7 is a waveform diagram of the output side current in the second embodiment of the disclosure;
fig. 8 is a distortion rate of the output side current in the second embodiment of the disclosure;
fig. 9 is a waveform diagram of the voltage current of the a-phase at the output side of the three-level bidirectional converter in the charging state according to the second embodiment of the present disclosure;
fig. 10 is a waveform diagram of the voltage current of the a-phase at the output side of the three-level bidirectional converter in the discharge state in the second embodiment of the present disclosure.
The specific implementation mode is as follows:
the present disclosure is further described with reference to the following drawings and examples.
It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs.
It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present disclosure. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.
The embodiments and features of the embodiments in the present disclosure may be combined with each other without conflict.
Example one
The embodiment of the disclosure provides a distributed control system based on three-level bidirectional current transformation.
The distributed control system based on three-level bidirectional variable current as shown in fig. 1 comprises a main circuit and a control circuit; the main circuit comprises a low-pass filter, a direct-current filter, a three-level bidirectional converter, a PWM converter and a driving and protecting circuit; the control circuit comprises a control regulator and a current tracking control circuit;
the three-level bidirectional converter obtains fundamental wave positive sequence current components of instantaneous active current components and instantaneous reactive current components from the collected three-phase load side through coordinate transformation and a low-pass filter, and converts the whole sequence fundamental wave components of three-phase current into direct current; i based on instantaneous voltage vector orientationp-iqAnd (5) obtaining the compensation command current by a detection method, and finishing the processing of the current fundamental component.
Fig. 2 is a main circuit topology structure diagram of a three-level bidirectional converter; wherein u issa、usb、uscInputting phase voltage for a three-phase system; i.e. ia、ib、icThree phases for converter outputCurrent flow; l issAnd RsLine inductance and resistance of the power grid respectively; u shapeDCIs a direct current side voltage; c1And C2Two filter capacitors connected in series at the DC side and having voltage of udc1And udc2The current flowing is idc1And idc2；iNIs the midpoint current.
Each phase bridge arm in the three-level bidirectional converter consists of two clamping diodes, four switching tubes and four freewheeling diodes; wherein, the four switch tubes are respectively the first switch tube VT1A second switching tube VT2And a third switching tube VT3And a fourth switching transistor VT4(ii) a Wherein, the first switch tube VT1And a third switching tube VT3Complementary conduction, second switch tube VT2And a fourth switching transistor VT4And conducting complementarily. The main circuit of the three-level bidirectional converter has a switching function of
Figure BDA0003319729440000061
According to the switching function shown in formula (1), each phase bridge arm of the three-level bidirectional converter can be equivalent to a single-pole three-throw switch, and an equivalent circuit of the three-level bidirectional converter shown in fig. 3 is established.
According to the switching function shown in formula (1), each phase bridge arm of the three-level bidirectional converter has three switching states of 0, 1 and 2, which means that the three-phase bridge arm of the converter generates 3327 combinations of switch states. The 27 switching states of the three-phase three-level bidirectional converter correspond to 19 voltage space vectors respectively, and a voltage space vector distribution diagram as shown in fig. 4 can be obtained according to the coordinate positions of the 19 voltage vectors.
Example two
This embodiment describes a distributed control method based on three-level bidirectional conversion based on the distributed control system based on three-level bidirectional conversion in the first embodiment.
A distributed control method based on three-level bidirectional variable flow comprises the following steps:
the three-level bidirectional converter collects three-phase load instantaneous current;
coordinate transformation and low-pass filtering are carried out on the obtained three-phase load instantaneous current, and the integral fundamental current component of the instantaneous active current component and the instantaneous reactive current component in the three-phase load instantaneous current are respectively obtained;
according to i oriented based on instantaneous voltage vectorp-iqAnd calculating the positive sequence current component of the three-phase current by using a detection method to obtain a compensation command current, and finishing the processing of the current fundamental component.
As one or more embodiments, the voltage outer loop is PI controlled as shown in FIG. 1, wherein
Figure BDA0003319729440000071
Is the actual voltage V on the DC sidedcGiven values of (a). Deviation of both
Figure BDA0003319729440000072
After the adjustment of the PI device, an adjustment signal delta i is obtainedpIf, if
Figure BDA0003319729440000073
Then Δ ipWhen the distributed energy storage system is in a charging state, the current is instructed
Figure BDA0003319729440000074
If it is
Figure BDA0003319729440000075
Then Δ ipWhen the voltage is negative, the distributed energy storage system is in a discharging state, the two conditions are analyzed, K is a set discharging coefficient, and if KIp is smaller than the maximum output current value I of the energy storage systempmaxWhen the output current is larger than KIp, the system discharges according to the KIp value, and if the output current is larger than the maximum output current I of the energy storage systempmaxIn time, the system discharges according to the maximum output current value of the energy storage system, so that the given voltage can be adjusted
Figure BDA0003319729440000081
Controls the charging and discharging process of the energy storage system.
Figure BDA0003319729440000082
The design method for limiting the output current of the bidirectional converter is as follows:
if the effective value of the command current does not exceed the effective value I of the rated output current of the bidirectional convertereIf so, the bidirectional converter outputs according to the demand of the instruction current;
if the effective value of the command current exceeds the effective value I of the rated output current of the bidirectional convertereAnd the bidirectional converter outputs according to the maximum rated output capacity to prevent the overload phenomenon.
Recording three-phase command current instantaneous value as iaf(k)、ibf(k)、icf(k)In practical application, the instantaneous value of the current compensation command and all instantaneous values in a period before the moment need to be stored and calculated, and the effective value of the three-phase command current at the moment is obtained as follows:
Figure BDA0003319729440000083
Figure BDA0003319729440000084
Figure BDA0003319729440000085
let IceDefining a command current overload coefficient for the output rated current of the bidirectional converter:
Figure BDA0003319729440000086
the output current limit function of the bi-directional converter:
Figure BDA0003319729440000091
multiplying the command current by a limiting function K (k) to obtain a command current signal processed by an output current limiting function:
Figure BDA0003319729440000092
as one or more embodiments, a schematic diagram of coordinate transformation is shown in FIG. 5; specifically, the three-phase instantaneous voltage values collected by the power frequency voltage transformer are respectively recorded as ea、eb、ecConverting the voltage from a three-phase coordinate system to a two-phase coordinate system according to the power conservation principle, wherein the phase difference between two adjacent phases of the three-phase coordinate system is 120 degrees, the phase difference between two adjacent phases of the two-phase coordinate system is 90 degrees, and obtaining the voltage according to the equivalent rotating magnetic field
Figure BDA0003319729440000093
Figure BDA0003319729440000094
The coefficients of the two-phase α β coordinate system transformed into the three-phase coordinate system can be reversely deduced from the above formula:
Figure BDA0003319729440000095
as can be seen from FIG. 5, sin θ can be accurately measured from the instantaneous values of the three-phase voltagese、cosθe：
Figure BDA0003319729440000096
Figure BDA0003319729440000101
In the α β coordinate system, the vector eα、eβSynthetically rotatable voltage vector
e＝eα+eβ＝Em∠θe
Within the two-phase stationary coordinate system α β, the voltage vector e is constantly undergoing a rotational movement with an angular velocity ω ═ 2 π f. Thus, it is considered to establish a dq synchronous rotating coordinate system, wherein the d axis is oriented according to the voltage vector in the α β coordinate system, the q axis is orthogonal to the d axis and is 90 ° after the d axis, so that in the dq synchronous rotating coordinate system with the angular velocity ω ═ 2 π f, the work frequency positive sequence component in the voltage vector e is converted into a direct current component, and the projection on the dq coordinate axis is
ep＝e＝eα+eβ＝Em∠θe
eq＝0
Since in the energy storage device only the active power is considered, not the reactive compensation and the harmonic suppression, a power is given
Figure BDA0003319729440000102
The following transformation considers only ipThe positive sequence current component is obtained by the following inverse transformation, and then the positive sequence current component of the three-phase current is obtained by the two-phase to three-phase inverse transformation (the specific flow is shown in fig. 6):
iαf＝cosθeip
iβf＝sinθeip
Figure BDA0003319729440000103
to verify the orientation i based on the instantaneous voltage vectorp-iqThe effectiveness of a current detection method and a new method for directly controlling the instantaneous current of a three-level bidirectional converter is established to imitateA true platform; the main parameters are as follows:
TABLE 1 simulation parameters
Figure BDA0003319729440000111
Firstly, the quality of the output current waveform of the bidirectional converter is verified.
FIG. 7 is a graph of the instantaneous voltage vector orientation ip-iqThe detection current detection method and the instantaneous current direct control method of the three-level bidirectional converter are used for detecting the current waveform diagram of the output side of the bidirectional converter under the condition, and fig. 8 shows the output side current distortion rate which is 2.24 percent and has better output current waveform quality.
And secondly, verifying the performance of the charging state of the bidirectional converter.
Setting the given value of the voltage on the direct current side as 800V, setting the output amplitude limit of the PID regulator as 60A, and automatically setting the converter in a rectification state. Fig. 9 shows waveforms of a-phase voltage and a-phase output current of the inverter. According to the figure, the current and voltage phases are the same in the charging state, and the inverter absorbs active power from the power grid, transfers and stores the active power into the battery. At this time, the peak current was 49.11A, the effective current was 34.72A, the theoretically calculated peak current was 48.98A, and the effective current was 34.64A, which substantially coincided with the theoretically calculated value.
And finally, verifying the discharge state performance of the bidirectional converter.
The given value of the voltage on the direct current side is set to be 650V, the output amplitude limit of the PID regulator is 60A, and the converter is automatically in an inversion power generation state. Fig. 10 shows waveforms of the inverter a-phase voltage and a-phase output current. According to the figure, the current and voltage phases are opposite in the discharging state, and the converter transmits active power to the power grid. At this time, the peak value of the current is 50.03A, the effective value is 35.38A, the distortion rate is 2.58%, the peak value of the theoretically calculated current is 48.98A, the effective value is 34.64A, and the simulated current basically matches the theoretically calculated value.
Although the present disclosure has been described with reference to specific embodiments, it should be understood that the scope of the present disclosure is not limited thereto, and those skilled in the art will appreciate that various modifications and changes can be made without departing from the spirit and scope of the present disclosure.

Claims (10)

1. A distributed control system based on three-level bidirectional variable current is characterized by comprising a main circuit and a control circuit; the main circuit comprises a low-pass filter, a direct-current filter, a three-level bidirectional converter, a PWM converter and a driving and protecting circuit; the control circuit comprises a control regulator and a current tracking control circuit;
the three-level bidirectional converter obtains fundamental wave positive sequence current components of instantaneous active current components and instantaneous reactive current components from the collected three-phase load side through coordinate transformation and a low-pass filter, and converts the whole sequence fundamental wave components of three-phase current into direct current; i based on instantaneous voltage vector orientationp-iqAnd (5) obtaining the compensation command current by a detection method, and finishing the processing of the current fundamental component.
2. The distributed control system based on three-level bidirectional current transformation as recited in claim 1, wherein each phase leg of said three-level bidirectional current transformer is comprised of two clamping diodes, four switching tubes and four freewheeling diodes.
3. The distributed control system based on three-level bidirectional variable current as recited in claim 2, wherein said four switching tubes are a first switching tube, a second switching tube, a third switching tube and a fourth switching tube, respectively; the first switching tube and the third switching tube are conducted complementarily, and the second switching tube and the fourth switching tube are conducted complementarily.
4. A three-level bidirectional converter-based distributed control system as defined in claim 1, wherein said power-supply side of said three-level bidirectional converter employs a configuration in which two capacitors are connected in series to generate three levels.
5. A distributed control method based on three-level bidirectional variable flow is characterized by comprising the following steps:
the three-level bidirectional converter collects three-phase load instantaneous current;
coordinate transformation and low-pass filtering are carried out on the obtained three-phase load instantaneous current, and the integral fundamental current component of the instantaneous active current component and the instantaneous reactive current component in the three-phase load instantaneous current are respectively obtained;
according to i oriented based on instantaneous voltage vectorp-iqAnd calculating the positive sequence current component of the three-phase current by using a detection method to obtain a compensation command current, and finishing the processing of the current fundamental component.
6. A distributed control method based on three-level bidirectional variable current as recited in claim 5, characterized in that said i is oriented according to an instantaneous voltage-based vectorp-iqThe method for calculating the positive sequence current component of the three-phase current by the detection method comprises the following specific steps:
acquiring three-phase instantaneous voltage through a power frequency voltage transformer, and converting the voltage in a three-phase coordinate system into the voltage in a two-phase coordinate system according to a power conservation principle;
performing back-stepping calculation according to the voltage in the two-phase coordinate system to obtain a coordinate coefficient and a vector angle of three-phase instantaneous voltage in the three-phase coordinate system;
combining the voltages in the two-phase coordinate system to obtain a rotating voltage vector;
and constructing a dq synchronous rotation coordinate system by using the voltage vector orientation in the two-phase coordinate system as a d axis and using a q axis which is orthogonal to the voltage vector and lags behind by 90 degrees as a q axis, solving the projection of the voltage vector on a dq coordinate axis and the positive sequence current component, and obtaining the three-phase current positive sequence current component through the transformation of the coordinate system.
7. The distributed control method based on three-level bidirectional current transformation as recited in claim 5, wherein each phase bridge arm in the three-level bidirectional current transformer is provided with four switching tubes; the four switch tubes are respectivelyFirst switch tube VT1A second switching tube VT2And a third switching tube VT3And a fourth switching transistor VT4(ii) a Wherein, the first switch tube VT1And a third switching tube VT3Complementary conduction, second switch tube VT2And a fourth switching transistor VT4And conducting complementarily.
8. The distributed control method based on three-level bidirectional current transformer as recited in claim 7, wherein the switching function of said main circuit of said three-level bidirectional current transformer is
Figure FDA0003319729430000031
9. A distributed control method based on three-level bidirectional current transformation as defined in claim 8, characterized in that each phase leg of the three-level bidirectional current transformer is equivalent to a single-pole-three-throw switch according to said switching function, establishing an equivalent circuit of the three-level bidirectional current transformer.
10. The distributed control method based on three-level bidirectional converter as recited in claim 8, characterized in that each phase leg of the three-level bidirectional converter is switched by three switching states of 0, 1 and 2 according to said switching function, and the three-phase leg generates 33And (4) switching state combination.
CN202111242529.0A 2021-10-25 2021-10-25 Distributed control system and method based on three-level bidirectional conversion Active CN113991672B (en)

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