CN105391313B - A kind of control method of modularization multi-level converter - Google Patents

A kind of control method of modularization multi-level converter Download PDF

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Publication number
CN105391313B
CN105391313B CN201511020648.6A CN201511020648A CN105391313B CN 105391313 B CN105391313 B CN 105391313B CN 201511020648 A CN201511020648 A CN 201511020648A CN 105391313 B CN105391313 B CN 105391313B
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group
module
module group
voltage
bridge arm
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CN105391313A (en
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黄守道
荣飞
陈盼庆
罗德荣
龚喜长
李旺
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Hunan University
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Hunan University
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Classifications

    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02MAPPARATUS 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
    • H02M7/00Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02MAPPARATUS 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
    • H02M7/00Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/42Conversion of dc power input into ac power output without possibility of reversal
    • H02M7/44Conversion of dc power input into ac power output without possibility of reversal by static converters
    • H02M7/48Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/483Converters with outputs that each can have more than two voltages levels
    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02MAPPARATUS 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
    • H02M7/00Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/42Conversion of dc power input into ac power output without possibility of reversal
    • H02M7/44Conversion of dc power input into ac power output without possibility of reversal by static converters
    • H02M7/48Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/483Converters with outputs that each can have more than two voltages levels
    • H02M7/4835Converters with outputs that each can have more than two voltages levels comprising two or more cells, each including a switchable capacitor, the capacitors having a nominal charge voltage which corresponds to a given fraction of the input voltage, and the capacitors being selectively connected in series to determine the instantaneous output voltage
    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02MAPPARATUS 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
    • H02M7/00Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/42Conversion of dc power input into ac power output without possibility of reversal
    • H02M7/44Conversion of dc power input into ac power output without possibility of reversal by static converters
    • H02M7/48Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/53Conversion of dc power input into ac power output without 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
    • H02M7/537Conversion of dc power input into ac power output without 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, e.g. single switched pulse inverters
    • H02M7/5387Conversion of dc power input into ac power output without 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, e.g. single switched pulse inverters in a bridge configuration

Abstract

The invention discloses a kind of control method of modularization multi-level converter, by the 2 of bridge armNIndividual submodule is according to 20,21,22...2N‑1, 1 is divided into N+1 module group, and submodule bulk state is consistent in every group of group in work, that is, is simultaneously turned on or turned off.Often assemble and put a voltage sensor, for measuring this group of magnitude of voltage.Voltage stabilizing control method, voltage recording method, modulator approach and pressure equalizing control method according to this structure design.The capacitance voltage sum of each mutually all submodules is stablized in voltage stabilizing control using pi regulator;Voltage recording method is used for preserving the magnitude of voltage of each module group;Modulator approach is used for determining the on off operating mode of modules group;Pressure and Control are used for keeping the average value of component submodule voltage to keep in balance.The present invention reduces system hardware complexity and reduction MMC cost using the control mode of submodule component group, a large amount of voltage transformers reduced needed for MMC systems.

Description

A kind of control method of modularization multi-level converter
Technical field
Patent of the present invention belongs to the method for flexible direct-current transmission field, more particularly to modularization multi-level converter control.
Background technology
Technology of HVDC based Voltage Source Converter is the effective way for building flexible, strong, efficient power network and making full use of regenerative resource Footpath, represents the future thrust of direct current transportation, it has also become one of key technology of New Generation of Intelligent power network.Flexible transmission work The modularization multi-level converter of one of core devices in journey, its stability, economy is still restriction flexible DC power transmission skill One of key point of art large-scale commercial applications operation.Patent of the present invention is set about from the economy for improving modularization multi-level converter, On the premise of the stability of system is ensured, the quantity of submodule voltage sensor is reduced, and then reduce system cost.
The maximum advantage of Modularized multi-level converter sub-module cascade is, on the premise of low voltage stress, leads to Cross the output voltage that submodule series connection obtains voltage levels.Therefore, in actual engineering project, contain largely per phase bridge arm Submodule.One of emphasis and difficult point of modularization multi-level converter control strategy are to control each submodule capacitor voltage Stabilization is in submodule reference voltage, and conventional control method has phase-shifting carrier wave and nearest level to approach.Two kinds of basic methods are all Need to gather the voltage of storage capacitor in each submodule, and then pass through conducting or excision that control algolithm determines correspondence submodule State.This pattern causes MMC systems to configure substantial amounts of voltage sensor, and this undoubtedly adds the complexity of system and improved The cost of system.
Each submodule is equipped with the pattern of a voltage sensor not condition essential to the normal operation of transverter, therefore Many methods for being directed to reducing voltage sensor occur.Simplest method is direct cancellation voltage sensor, and setting is per phase The submodule of bridge arm is turned on or turned off according to certain control strategy, and son is maintained with shut-off strategy by presetting conducting Module capacitance voltage stabilization.The reliability by the system that substantially reduces of the open loop control mode.Another way passes through bridge arm electricity Stream and DC bus-bar voltage combination submodule cut-off status predication capacitance voltage.To improve the accuracy of prediction, some methods are carried Go out each bridge arm and be equipped with a small amount of voltage sensor, regularly resetted the submodule capacitor voltage of prediction.These are using prediction What the method for capacitance voltage was normally run in system, system is in of short duration uncontrollable state, and system abnormal condition is reacted Relatively slow, the reliability of system will be affected.
The content of the invention
Technical problem solved by the invention is that there is provided a kind of modular multilevel change of current in view of the shortcomings of the prior art The control method of device, under conditions of the present invention ensure that output voltage waveforms meet engine request, is greatly reduced voltage biography The quantity of sensor, and the quantity of the more reductions of bridge arm submodule quantity is more notable.
To achieve the above object, the technical solution used in the present invention is:
A kind of control method of modularization multi-level converter, the modularization multi-level converter (MMC) uses three-phase Six bridge arm topological structures, per upper and lower two bridge arms are mutually included, each bridge arm is by 2NIndividual SM submodules and 1 inductance L series connection and Into upper and lower bridge arm tie point draws phase line;Three phase line accesses public electric wire net;N is integer, Wherein,Function is to round up;UdcFor by the DC voltage of transverter, UsmFor SM submodule reference voltages;
Each SM submodules are a half-bridge current transformers, by two IGBT pipes T1 and T2, two diode D1 and D2 and one Individual electric capacity C is constituted;Wherein, IGBT pipes T1 emitter stage is connected with IGBT pipes T2 colelctor electrode and constitutes SM anode, and IGBT is managed T1 colelctor electrode is connected with electric capacity C positive pole, and IGBT pipes T2 emitter stage is connected with the negative pole of electric capacity and constitutes SM negative terminal;D1 With T1 reverse parallel connections, D2 and T2 reverse parallel connections;IGBT pipes T1 and T2 gate pole receive control wave;
The 2 of bridge arm on per phaseNIndividual SM submodules and 1 inductance L are sequentially connected in series, that is, are going up first SM submodule of bridge arm just End is connected with DC side positive pole;Anode in i-th middle of SM submodule is connected with the negative terminal of the i-th -1 SM submodule, The negative terminal of i-th of SM submodule is connected with the anode of i+1 SM submodules, i=2, and 3 ..., 2N-1;Upper bridge arm the 2ndNIndividual SM The negative terminal of module is connected with inductance L one end, and the inductance L other ends draw phase line;
The inductance L and 2 of bridge arm under per phaseNIndividual SM submodules are sequentially connected in series, i.e., phase line is drawn in inductance L one end, and inductance L is another End is connected with the anode of lower first SM submodule of bridge arm;Anode and the i-th -1 SM in i-th middle of SM submodule The negative terminal of module is connected, and the negative terminal of i-th of SM submodule is connected with the anode of i+1 SM submodules, i=2,3 ..., 2N- 1;Lower bridge arm the 2ndNThe negative terminal of individual SM submodules is connected with DC side negative pole;
DC side power supply neutral earthing;
For any phase in three-phase (A phases, B phases and C phases), the control method comprises the following steps:
Step 1, module packet;
Step 2, voltage stabilizing control, stablize the capacitance voltage sum of each mutually all submodules using pi regulator;
Step 3, modulation, for determining the on off operating mode of modules group;
The module packet of the step 1, specifically includes following steps:
By the 2 of each bridge arm of transverterNIndividual SM submodules are divided into N+1 module group, and preceding N groups respectively include 2i-1Individual SM submodules Block, i be module group sequence number, i=1,2 ..., N (i.e. the 1st group include 20Individual SM submodules, the 2nd group includes 21Individual SM submodules, 3rd group includes 22Individual SM submodules, the like, N groups include 2N-1Individual SM submodules), N+1 groups include 1 SM submodule Block;Each module group voltage sensor in parallel, the total voltage for measuring SM submodule electric capacity in the module group;In work Submodule bulk state is consistent in every group of group, that is, is simultaneously turned on or turned off;
The voltage stabilizing control of the step 2, specifically includes following steps:
2.1) magnitude of voltage of the bridge arm from first module group to the N+1 module group in the phase is measured, by voltage measuring value U is designated as respectivelyaup1,Uaup2,....,Uaupi,....,Uaup(N+1);Measure bridge arm under the phase individual from first module group to N+1 The magnitude of voltage of module group, U is designated as by voltage measuring value respectivelyabelow1, Uabelow2..., Uabelowi,....,Uabelow(N+1)
2.2) for N+1 module group of each bridge arm, when some module group is in the conduction state, the module group is preserved Voltage measuring value;To i-th of module group of bridge arm in the phase, its voltage measuring value is saved as into voltage record value Uasupi;To this I-th of module group of bridge arm, U is recorded as by its voltage measuring value under phaseasbelowi;Should until being updated after module group conducting next time Voltage record value;
2.3) according to step 2.1) obtained voltage measuring value calculates the voltage sum U of mutually each module groupaFor:
2.4) the shared K module group conducting of measurement moment is set, the output U that voltage stabilizing is controlled is calculated according to below equationaref1
Uaref1=(Usm-Ua/K)(Kp+Ki/s)
Wherein, KpFor proportionality coefficient, KiFor integral coefficient, 1/s is that (integrating factor is to (U to integrating factorsm-Ua/ K) carry out Integration, that is, over time, ceaselessly add up this error amount);
2.5) setting transverter needs the voltage exported as Uaref2, the modulation voltage of transverter is calculated according to below equation Uaref
Uaref=Uaref1+Uaref2
The modulation of the step 3, specifically includes following steps:
3.1) according to step 2.5) calculate obtain modulation voltage Uaref, bridge arm and lower bridge arm module group in the phase are calculated respectively Conducting number NaupAnd Nabelow
Naup=round ((Udc/2-Uaref)/Usm)
Nabelow=round ((Udc/2+Uaref)/Usm)
Wherein, round () is the function that rounds up;
3.2) by NaupBinary number is converted into, N is designated asnaup;NnaupFrom low level to each high-order, respectively with upper bridge arm 1st to n-th module group correspond;According to NnaupIn each bit value, following control is carried out to each module group:
3.2.1) work as NnaupIn at least 2 be equal to 1 when, turn on NnaupIn be equal to 1 the corresponding module group in position, turn off it Its module group (including NnaupIn be equal to 0 the corresponding module group in position, and the N+1 module group);
3.2.2) work as NnaupIn everybody when being congruent to 0, all module groups of bridge arm in shut-off;
3.2.3) work as NnaupOnly 1 when being equal to 1, it is other everybody when being equal to 0, if the position equal to 1 is i-th bit, and set The measured value of bridge arm current is i in the phaseaup
If iaupDirection is SM chargings direction, i.e. iaup>0, then use and be carried out as follows Pressure and Control:
If (a) Uasupi/Naup>UsmAnd i>1, then the 1st to the i-th -1 module group and the N+1 module group are turned on, it is turned off Its module group (i.e. i-th to n-th module group);
If (b) Uasupi/Naup>UsmAnd i=1, then N+1 group module groups are turned on, other module groups the (the i.e. the 1st to N are turned off Individual module group);
If (c) Uasupi/Naup≤Usm, then i-th group of module group is turned on, and turn off other module groups;
If iaupDirection is SM course of discharges, i.e. iaup<0, then Pressure and Control are carried out in the following way:
If (a) Uasupi/Naup<UsmAnd i>1, then the 1st group is turned on to the i-th -1 group and the N+1 module group, turns off other moulds Block group (i.e. i-th to n-th module group);
If (b) Uasupi/Naup<UsmAnd i=1, then N+1 group module groups are turned on, other module groups the (the i.e. the 1st to N are turned off Individual module group);
If (c) Uasupi/Naup≥Usm, then i-th group of module group is turned on, and turn off other module groups;
3.3) by NabelowBinary number is converted into, N is designated asnabelow;NnabelowFrom low level to each high-order, respectively with The 1st of lower bridge arm module group to n-th module group is corresponded;According to NnabelowIn each bit value, each module group is entered Row is following to be controlled:
3.3.1) work as NnabelowAt least 2 when being 1, turn on NnabelowIn be equal to 1 the corresponding module group in position, turn off it Its module group (including NnabelowIn be equal to 0 the corresponding module group in position, and the N+1 module group);
3.3.2) work as NnabelowIn everybody when being congruent to 0, all module groups of the lower bridge arm of shut-off;
3.3.3) work as NnabelowOnly 1 when being equal to 1, it is other everybody when being equal to 0, if the position equal to 1 is i-th bit, and If the measured value of bridge arm current is i under the phaseabelow
If iabelowDirection is SM chargings direction, i.e. iabelow>0, then use and be carried out as follows Pressure and Control:
If (a) Uasbelowi/Nabelow>UsmAnd i>1, then the 1st group is turned on to the i-th -1 group and the N+1 module group, turns off it Its module group (i.e. i-th to n-th module group);
If (b) Uasbelowi/Nabelow>UsmAnd i=1, then N+1 group module groups are turned on, other module groups the (the i.e. the 1st are turned off To n-th module group);
(c)Uasbelowi/Nabelow≤Usm, then i-th group of module group is turned on, and turn off other module groups;
If iabelowDirection is SM course of discharges, i.e. iabelow<0, then Pressure and Control are carried out in the following way:
If (a) Uasbelowi/Nabelow<UsmAnd i>1, then the 1st group is turned on to the i-th -1 group and the N+1 module group, turns off it Its module group (i.e. i-th to n-th module group);
If (b) Uasbelowi/Nabelow<UsmAnd i=1, then N+1 group module groups are turned on, other module groups the (the i.e. the 1st are turned off To n-th module group);
(c)Uasbelowi/Nabelow≥Usm, then i-th group of module group is turned on, and turn off other module groups.
The average value for keeping component submodule voltage by above Pressure and Control process is kept in balance.
The step 2.4) in, Proportional coefficient Kp=1, integral coefficient Ki=100.
As a kind of embodiment of the present invention, the N values are 3, and inductance value L is 2.8mH, and capacitance C is 2800uH, directly Flow side voltage UdcFor 800V, SM submodule reference voltages UsmFor 100V.
The present invention is by the 2 of bridge armNIndividual submodule is according to 20,21,22...2N-1, 1 is divided into N+1 module group, every group in work Submodule bulk state is consistent in group, that is, is simultaneously turned on or turned off.Every group only configures a voltage sensor, for measuring this Group magnitude of voltage.Voltage stabilizing control method, voltage recording method, modulator approach and pressure equalizing control method according to this structure design. The capacitance voltage sum of each mutually all submodules is stablized in voltage stabilizing control using pi regulator;Voltage recording method is used for preserving each mould The magnitude of voltage of block group;Modulator approach is used for determining the on off operating mode of modules group;Pressure and Control are used for keeping component submodule The average value of voltage is kept in balance.The control strategy uses the control mode of submodule component group, a large amount of to reduce in MMC systems Required voltage transformer, and then reduce system hardware complexity and reduction MMC cost, with good engineer applied valency Value.
The beneficial effects of the invention are as follows:1) voltage transformer is reduced;2) cost of system is greatly lowered.
Brief description of the drawings
Fig. 1 modular multilevel converter structure schematic diagrames;
Bridge arm submodule is grouped schematic diagram in Fig. 2 A phases;
Fig. 3 A phase Pressure and Control block diagrams;
The module groups of Fig. 4 the 3rd are turned on and excision schematic diagram;Fig. 4 (a) is the 3rd module group conducting schematic;Fig. 4 (b) is the 3rd Module group cuts off schematic diagram;
Fig. 5 is A phase each group submodule voltages.Wherein Fig. 5 (a) is upper bridge arm each group submodule voltage, and Fig. 5 (b) is lower bridge Arm each group submodule voltage;
Fig. 6 A phases export phase voltage.
Embodiment
In order that technical problem solved by the invention, technical scheme and beneficial effect are more clearly understood, below in conjunction with Accompanying drawing, the present invention will be described in further detail.It should be appreciated that specific embodiment described herein is only to explain this Invention, is not intended to limit the present invention.
Fig. 1 is modular multi-level converter topological structure figure, is made up of three-phase bridge arm.Per mutually two bridge arms containing above and below, often Bridge arm contains 2NIndividual identical submodule and a filter inductance L.Submodule is made up of two IGBT and storage capacitors.
Fig. 2 is the schematic diagram that bridge arm submodule is grouped in A phases.In this embodiment, N values are 3, and inductance value L is 2.8mH, capacitance C are 2800uH, DC voltage UdcFor 800V, SM submodule reference voltages UsmFor 100V.According to module point The mode of group, is by 2N(2N=8) individual SM submodules are divided into N+1 module group, and the 1st group includes 20Individual SM submodules, the 2nd group Include 21Individual SM submodules, the 3rd group includes 22Individual SM submodules, the 4th group includes 1 SM submodule.Therefore, bridge arm submodule point Into 4 groups, each group submodule number is followed successively by 1,2,4,1.B, C are similar.
Fig. 3 is A phase voltage stabilizing control block diagrams.Assuming that voltage of the bridge arm from first module group to the N+1 module group in A phases Measured value is respectively Uaup1, Uaup2, Uaup3, Uaup4.Voltage of the bridge arm from first module group to the N+1 module group under A phases Measured value is respectively Uabelow1, Uabelow2, Uabelow3, Uabelow4, then the module group voltage sum U that A phases are respectively turned onaFor:
Assuming that measurement moment shared K submodule conducting, then voltage stabilizing control is described as:
Uaref1=(Usm-Ua/K)(Kp+Ki/s)
Wherein, Kp=1, Ki=100, s are integrating factor, Uaref1It is the output of voltage stabilizing control;
Assuming that MMC current transformers need the voltage exported to be Uaref2, value is 400sin (100 π t), t in this embodiment It is time variable, the timing since the MMC conducting times of running.The then modulation voltage U of MMC current transformersarefFor:Uaref=Uaref1+ Uaref2
A phases upper and lower bridge arm conducting number NaupAnd NabelowRespectively:
Naup=round ((Udc/2-Uaref)/Usm)
Nabelow=round ((Udc/2+Uaref)/Usm)
Wherein, round () is the function that rounds up;
By NaupIt is converted into binary number and obtains Nnaup;NnaupFrom low level to each high-order, with upper bridge arm module group 1st group corresponds respectively to N groups;
Work as NnaupAt least 2 when being 1, if NnaupA certain position be 1, then turn on corresponding module group;The tune of lower bridge arm Process processed is similar;
B, C phase modulated process and A are similar.
Fig. 4 is the conducting of the 3rd module group and excision schematic diagram.Submodule state consistency in every group of group, i.e., lead simultaneously in work Logical and shut-off.When this group of submodule conducting, the voltage measuring value of the module group is preserved, until after module group conducting next time Update the record value;To i-th group of module of bridge arm in A phases, if its voltage record value is Uasupi;To i-th group of module of bridge arm under A phases, Voltage record value is Uasbelowi
Work as NnaupOnly i-th bit is 1, it is other everybody when being all 0, Pressure and Control are carried out to the module group corresponding to this; Assuming that the measured value of bridge arm current is i in A phasesaup, and iaupDirection is SM chargings direction, i.e. iaup>0, then use and be carried out as follows Pressure and Control:
If (a) Uasupi/Naup>UsmAnd i>1, then the 1st to the i-th -1 module group and the N+1 module group are turned on, it is turned off Its module group (i.e. i-th to n-th module group);
If (b) Uasupi/Naup>UsmAnd i=1, then turn on N+1 group module groups, turn off other module groups the (the i.e. the 1st to the N number of module group);
If (c) Uasupi/Naup≤Usm, then i-th group of module group is turned on, and turn off other module groups;
Assuming that the measured value of bridge arm current is i in A phasesaup, and iaupDirection is SM course of discharges, i.e. iaup<0, then use Following manner carries out Pressure and Control:
If (a) Uasupi/Naup<UsmAnd i>1, then the 1st group is turned on to the i-th -1 group and the N+1 module group, turns off other moulds Block group (i.e. i-th to n-th module group);
If (b) Uasupi/Naup<UsmAnd i=1, then N+1 group module groups are turned on, other module groups the (the i.e. the 1st to N are turned off Individual module group);
If (c) Uasupi/Naup≥Usm, then i-th group of module group is turned on, and turn off other module groups;
Bridge arm pressure equalizing control method is similar under A phases;B, C pressure equalizing control method are similar with A phase pressure equalizing control methods.
Fig. 5 is A phase each group submodule voltages.Wherein Fig. 5 (a) is upper bridge arm each group submodule voltage, and Fig. 5 (b) is lower bridge Arm each group submodule voltage.It can be seen that each submodule capacitor voltage of upper bridge arm is stable in 100V, ripple is 1.5V, meets engine request.This also demonstrates Pressure and Control strategy validity proposed by the present invention.
Fig. 6 is A phase output voltages, fundamental voltage output of voltage amplitude 400V, and total harmonic distortion is 4.4%, and ripple is 3V, is met Engine request, it was demonstrated that the validity of control strategy proposed by the present invention.

Claims (3)

1. a kind of control method of modularization multi-level converter, it is characterised in that
The modularization multi-level converter uses the bridge arm topological structure of three-phase six, per mutually including upper and lower two bridge arms, Mei Geqiao Arm is by 2NIndividual SM submodules and 1 inductance L are in series, and upper and lower bridge arm tie point draws phase line;Three phase line accesses common electrical Net;N is integer,Wherein,Function is to round up;UdcFor by the DC side of transverter electricity Pressure, UsmFor SM submodule reference voltages;
Each SM submodules are a half-bridge current transformers, by two IGBT pipes T1 and T2, two diode D1 and D2 and electricity Hold C to constitute;Wherein, IGBT pipes T1 emitter stage is connected with IGBT pipes T2 colelctor electrode and constitutes SM anode, IGBT pipes T1's Colelctor electrode is connected with electric capacity C positive pole, and IGBT pipes T2 emitter stage is connected with the negative pole of electric capacity and constitutes SM negative terminal;D1 and T1 Reverse parallel connection, D2 and T2 reverse parallel connections;IGBT pipes T1 and T2 gate pole receive control wave;
The 2 of bridge arm on per phaseNIndividual SM submodules and 1 inductance L are sequentially connected in series, i.e., the anode of upper first SM submodule of bridge arm with DC side positive pole is connected;Anode in i-th middle of SM submodule is connected with the negative terminal of the i-th -1 SM submodule, i-th The negative terminal of SM submodules is connected with the anode of i+1 SM submodules, i=2, and 3 ..., 2N-1;Upper bridge arm the 2ndNIndividual SM submodules Negative terminal be connected with inductance L one end, the inductance L other ends draw phase line;
The inductance L and 2 of bridge arm under per phaseNIndividual SM submodules are sequentially connected in series, i.e., inductance L one end draw phase line, the inductance L other ends with The anode of lower first SM submodule of bridge arm is connected;Anode and the i-th -1 SM submodule in i-th middle of SM submodule Negative terminal be connected, the negative terminal of i-th of SM submodule is connected with the anode of i+1 SM submodules, i=2,3 ..., 2N-1;Under Bridge arm the 2ndNThe negative terminal of individual SM submodules is connected with DC side negative pole;
DC side power supply neutral earthing;
For any phase in three-phase, i.e. A phases, B phases and C phases, the control method comprises the following steps:
Step 1, module packet;
Step 2, voltage stabilizing control, stablize the capacitance voltage sum of each mutually all submodules using pi regulator;
Step 3, modulation, for determining the on off operating mode of modules group;
The module packet of the step 1, specifically includes following steps:
By the 2 of each bridge arm of transverterNIndividual SM submodules are divided into N+1 module group, and preceding N groups respectively include 2i-1Individual SM submodules, i is The sequence number of module group, i=1,2 ..., N, N+1 groups include 1 SM submodule;Each module group voltage sensor in parallel, Total voltage for measuring SM submodule electric capacity in the module group;Submodule bulk state is consistent in every group of group in work, i.e., same When turn on or turn off;
The voltage stabilizing control of the step 2, specifically includes following steps:
2.1) bridge arm in the phase is measured, from first module group to the magnitude of voltage of the N+1 module group, voltage measuring value to be distinguished It is designated as Uaup1,Uaup2,….,Uaupi,….,Uaup(N+1);Bridge arm is measured under the phase from first module group to the N+1 module group Magnitude of voltage, voltage measuring value is designated as U respectivelyabelow1, Uabelow2..., Uabelowi,….,Uabelow(N+1)
2.2) for N+1 module group of each bridge arm, when some module group is in the conduction state, the electricity of the module group is preserved Press measured value;To i-th of module group of bridge arm in the phase, its voltage measuring value is saved as into voltage record value Uasupi;To under the phase I-th of module group of bridge arm, U is recorded as by its voltage measuring valueasbelowi;Until updating the voltage after module group conducting next time Record value;
2.3) according to step 2.1) obtained voltage measuring value calculates the voltage sum U of mutually each module groupaFor:
<mrow> <msub> <mi>U</mi> <mi>a</mi> </msub> <mo>=</mo> <munderover> <mo>&amp;Sigma;</mo> <mrow> <mi>i</mi> <mo>=</mo> <mn>1</mn> </mrow> <mrow> <mi>N</mi> <mo>+</mo> <mn>1</mn> </mrow> </munderover> <msub> <mi>U</mi> <mrow> <mi>a</mi> <mi>u</mi> <mi>p</mi> <mi>i</mi> </mrow> </msub> <mo>+</mo> <munderover> <mo>&amp;Sigma;</mo> <mrow> <mi>i</mi> <mo>=</mo> <mn>1</mn> </mrow> <mrow> <mi>N</mi> <mo>+</mo> <mn>1</mn> </mrow> </munderover> <msub> <mi>U</mi> <mrow> <mi>a</mi> <mi>b</mi> <mi>e</mi> <mi>l</mi> <mi>o</mi> <mi>w</mi> <mi>i</mi> </mrow> </msub> </mrow> 1
2.4) the shared K module group conducting of measurement moment is set, the output U that voltage stabilizing is controlled is calculated according to below equationaref1
Uaref1=(Usm-Ua/K)(Kp+Ki/s)
Wherein, KpFor proportionality coefficient, KiFor integral coefficient, 1/s is integrating factor;
2.5) setting transverter needs the voltage exported as Uaref2, the modulation voltage U of transverter is calculated according to below equationaref
Uaref=Uaref1+Uaref2
The modulation of the step 3, specifically includes following steps:
3.1) according to step 2.5) calculate obtain modulation voltage Uaref, leading for bridge arm and lower bridge arm module group in the phase is calculated respectively Logical number NaupAnd Nabelow
Naup=round ((Udc/2-Uaref)/Usm)
Nabelow=round ((Udc/2+Uaref)/Usm)
Wherein, round () is the function that rounds up;
3.2) by NaupBinary number is converted into, N is designated asnaup;NnaupFrom low level to each high-order, respectively with upper bridge arm the 1st Corresponded to n-th module group;According to NnaupIn each bit value, following control is carried out to each module group:
3.2.1) work as NnaupIn at least 2 be equal to 1 when, turn on NnaupIn be equal to 1 the corresponding module group in position, turn off other moulds Block group, i.e. NnaupIn be equal to 0 the corresponding module group in position, and the N+1 module group;
3.2.2) work as NnaupIn everybody when being congruent to 0, all module groups of bridge arm in shut-off;
3.2.3) work as NnaupOnly 1 when being equal to 1, it is other everybody when being equal to 0, if the position equal to 1 is i-th bit, and set in the phase The measured value of bridge arm current is iaup
If iaupDirection is SM chargings direction, i.e. iaup>0, then use and be carried out as follows Pressure and Control:
If (a) Uasupi/Naup>UsmAnd i>1, then the 1st to the i-th -1 module group and the N+1 module group are turned on, other moulds are turned off Block group, i.e., i-th are to n-th module group;
If (b) Uasupi/Naup>UsmAnd i=1, then N+1 group module groups are turned on, other module groups, i.e., the the 1st to n-th mould are turned off Block group;
If (c) Uasupi/Naup≤Usm, then i-th group of module group is turned on, and turn off other module groups;
If iaupDirection is SM course of discharges, i.e. iaup<0, then Pressure and Control are carried out in the following way:
If (a) Uasupi/Naup<UsmAnd i>1, then the 1st group is turned on to the i-th -1 group and the N+1 module group, turns off other module groups, I.e. i-th to n-th module group;
If (b) Uasupi/Naup<UsmAnd i=1, then N+1 group module groups are turned on, other module groups, i.e., the the 1st to n-th mould are turned off Block group;
If (c) Uasupi/Naup≥Usm, then i-th group of module group is turned on, and turn off other module groups;
3.3) by NabelowBinary number is converted into, N is designated asnabelow;NnabelowFrom low level to each high-order, respectively with lower bridge The 1st of arm module group to n-th module group is corresponded;According to NnabelowIn each bit value, to each module group carry out with Lower control:
3.3.1) work as NnabelowAt least 2 when being 1, turn on NnabelowIn be equal to 1 the corresponding module group in position, turn off other moulds Block group, i.e. NnabelowIn be equal to 0 the corresponding module group in position, and the N+1 module group;
3.3.2) work as NnabelowIn everybody when being congruent to 0, all module groups of the lower bridge arm of shut-off;
3.3.3) work as NnabelowOnly 1 when being equal to 1, it is other everybody when being equal to 0, if the position equal to 1 is i-th bit, and set the phase The measured value of lower bridge arm current is iabelow
If iabelowDirection is SM chargings direction, i.e. iabelow>0, then use and be carried out as follows Pressure and Control:
If (a) Uasbelowi/Nabelow>UsmAnd i>1, then the 1st group is turned on to the i-th -1 group and the N+1 module group, turns off other moulds Block group, i.e., i-th are to n-th module group;
If (b) Uasbelowi/Nabelow>UsmAnd i=1, then N+1 group module groups are turned on, other module groups the (the i.e. the 1st to N are turned off Individual module group);
(c)Uasbelowi/Nabelow≤Usm, then i-th group of module group is turned on, and turn off other module groups;
If iabelowDirection is SM course of discharges, i.e. iabelow<0, then Pressure and Control are carried out in the following way:
If (a) Uasbelowi/Nabelow<UsmAnd i>1, then the 1st group is turned on to the i-th -1 group and the N+1 module group, turns off other moulds Block group, i.e., i-th are to n-th module group;
If (b) Uasbelowi/Nabelow<UsmAnd i=1, then N+1 group module groups are turned on, other module groups the (the i.e. the 1st to N are turned off Individual module group);
(c)Uasbelowi/Nabelow≥Usm, then i-th group of module group is turned on, and turn off other module groups.
2. the control method of modularization multi-level converter according to claim 1, it is characterised in that the step 2.4) In, Proportional coefficient Kp=1, integral coefficient Ki=100.
3. the control method of modularization multi-level converter according to claim 1, it is characterised in that the N values are 3, inductance value L are 2.8mH, and capacitance C is 2800uH, DC voltage UdcFor 800V, SM submodule reference voltages UsmFor 100V。
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