CN105720844B - A kind of more level HVDC transverters of Three phase serial module structureization - Google Patents
A kind of more level HVDC transverters of Three phase serial module structureization Download PDFInfo
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- CN105720844B CN105720844B CN201610256944.4A CN201610256944A CN105720844B CN 105720844 B CN105720844 B CN 105720844B CN 201610256944 A CN201610256944 A CN 201610256944A CN 105720844 B CN105720844 B CN 105720844B
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- 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
- H02M7/02—Conversion of ac power input into dc power output without possibility of reversal
- H02M7/04—Conversion of ac power input into dc power output without possibility of reversal by static converters
- H02M7/12—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M7/21—Conversion of ac power input into dc 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
- H02M7/217—Conversion of ac power input into dc 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
Abstract
The invention discloses a kind of more level HVDC transverters of Three phase serial module structureization, cost including DC output end, three-phase alternating current input terminal, the first transformer, the second transformer, third transformer, the first single-phase converter, the second single-phase converter and the third single-phase converter present invention is low, while can block direct-current short circuit electric current.
Description
Technical field
The invention belongs to high voltage, high-power power conversion device topological structure and its control strategy fields, are related to one kind
The more level HVDC transverters of Three phase serial module structureization.
Background technology
Modularization multi-level converter (multilevel modular converter, MMC) is voltage source converter
A kind of topological structure of (voltage source converter, VSC), by Marquardt and Lesnicar in 2002
IEEE Power Tech Conference are proposed, are the newest fruits of high voltage dc transmission technology development.Relative to two level
With three-level converter topological structure, MMC topological structures have many advantages, such as：Modularized design, by adjusting the series connection of submodule
The flexible variation of voltage and power grade may be implemented in number；Switching frequency is low, and loss declines；Output voltage waveforms are very smooth
And close to ideal sinusoidal waveform, harmonic content is few, and large capacity alternating current filter is not needed in net side；Fault ride-through capacity is strong etc..
Based on These characteristics, MMC is applied to the reliability and adaptability that direct current transportation can significantly improve DC transmission system.But
It is, in order to export the DC voltage of same voltage class, derailing switch number of packages to be used to be needed using the MMC systems of half-bridge or full-bridge
Twice or four times of two level VSC topology of tradition, thus cost too it is high be current MMC systems a major defect.Meanwhile directly
Stream side short trouble is also the main problem that current MMC is faced.Half-bridge submodule is used in Practical Project, when DC side occurs
When failure, since anti-paralleled diode remains to provide access for fault current, three-phase shortcircuit occurs for system approximation, and can not pass through
Locking transverter carrys out disengagement failure electric current, seriously endangers the safe and stable operation of system.And since zero passage is not present in DC current
Point, blow-out is difficult, and the manufacturing process of high-voltage large-capacity dc circuit breaker is still immature, at present still in the experimental stage, in engineering
In rarely have application.
Invention content
It is an object of the invention to overcome the above-mentioned prior art, it is more to provide a kind of Three phase serial module structure
Level HVDC transverters, the cost of the transverter is low, while can block direct-current short circuit electric current.
In order to achieve the above objectives, the more level HVDC transverters of Three phase serial module structureization of the present invention include direct current
Output end, three-phase alternating current input terminal, the first transformer, the second transformer, third transformer, the first single-phase converter, the second list
Phase current transformer and third single-phase converter, wherein three output ends of three-phase alternating current input terminal respectively in the first transformer just
One end of primary coil is connected in one end of primary coil and third transformer in grade one end of coil, the second transformer, the
Primary coil in the other end of primary coil and third transformer in the other end of primary coil, the second transformer in one transformer
The other end be connected, one end of secondary coil and third become in one end of secondary coil, the second transformer in the first transformer
In depressor one end of secondary coil respectively with the first auxiliary bridge arm in the first single-phase converter, the in the second single-phase converter
The first auxiliary bridge arm in one auxiliary bridge arm and third single-phase converter is connected；
The second auxiliary bridge arm in first single-phase converter is connected with the anode of DC output end, the first single-phase converter
In main bridge arm and the other end of secondary coil in the first transformer and second in the second single-phase converter assist bridge arm to be connected
It connects, in the main bridge arm and the second transformer in the second single-phase converter in the other end of secondary coil and third single-phase converter
Third auxiliary bridge arm is connected, the other end of secondary coil and straight in the main bridge arm in third single-phase converter and third transformer
The cathode of stream output end is connected；
The second auxiliary bridge arm in first single-phase converter, the second auxiliary bridge arm in the second single-phase converter and third list
The second auxiliary bridge arm in phase current transformer is sequentially connected in series by n/2 full-bridge submodule, the first inductance and first resistor, n
For the even number more than or equal to 2.
The first auxiliary bridge arm and main bridge arm composition first in the secondary coil of first transformer, the first single-phase converter are handed over
Side loop is flowed, the first auxiliary bridge arm in the secondary coil of the second transformer, the second single-phase converter and main bridge arm composition second
Side loop is exchanged, the first auxiliary bridge arm and main bridge arm composition in the secondary coil of third transformer, third single-phase converter the
Three exchange side loops, wherein the interior circular current of the first exchange side loop, the interior circular current of the second exchange side loop and third exchange
The interior circular current of side loop is all made of the active and reactive current feed-forward decoupling control method of exchange side and is controlled, the first exchange side
Main bridge arm in circuit, the main bridge arm in the second exchange side loop and the main bridge arm in third exchange side loop are all made of surely active
Power and determine alternating voltage control method and controlled, the first auxiliary bridge arm in the first exchange side loop, the second exchange side are returned
What the first auxiliary bridge arm in the first auxiliary bridge arm and third exchange side loop in road was all made of current oriention determines DC voltage
Control method is controlled.
Reactive power distribution coefficient k is introduced, realizes reactive power in the first exchange by adjusting reactive power distribution coefficient k
Distribution in side loop between main bridge arm and the first auxiliary bridge arm, second exchange in side loop main bridge arm and first assist bridge arm it
Between distribution and third exchange side loop in main bridge arm and first auxiliary bridge arm between distribution.
The second auxiliary bridge arm and main bridge arm in first single-phase converter form the first DC circuit, the second single-phase converter
In the second auxiliary bridge arm and main bridge arm form the second DC circuit, the second auxiliary bridge arm in third single-phase converter and main bridge
Arm forms third DC circuit, wherein interior circular current in interior circular current, the second DC circuit in the first DC circuit and the
Interior circular current in three DC circuits is controlled by the feedforward closed loop control method of DC current, in the first DC circuit
Main bridge arm, the main bridge arm in the second DC circuit and the main bridge arm in third DC circuit controlled by determining DC voltage
It makes, in the second auxiliary bridge arm in the first DC circuit, the second auxiliary bridge arm in the second DC circuit and third DC circuit
Second auxiliary bridge arm pass through constant DC voltage control.
In main bridge arm in main bridge arm, the second single-phase converter and third single-phase converter in first single-phase converter
Main bridge arm is sequentially connected in series by n half-bridge submodule.
The first auxiliary bridge arm in first single-phase converter, the first auxiliary bridge arm in the second single-phase converter and third list
The first auxiliary bridge arm in phase current transformer is sequentially connected in series by second resistance, the second inductance and n/2 half-bridge submodule.
The invention has the advantages that：
The more level HVDC transverters of Three phase serial module structureization of the present invention include the first single-phase converter, second
Single-phase converter and third single-phase converter, wherein the first single-phase converter, the second single-phase converter and third single-phase converter
It is connected in series with, using same switch device count, realizes the output of more High Level DC Voltage, be to effectively reduce
The cost and volume of system improve the reliability of system, while alternate circulation are not present, and are arranged without carrying out the controls such as loop current suppression
It applies, in addition, the second auxiliary bridge arm in the first single-phase converter, the second auxiliary bridge arm in the second single-phase converter and third list
The second auxiliary bridge arm in phase current transformer is sequentially connected in series by n/2 full-bridge submodule, short trouble occurs in DC side
When, the generation of direct-current short circuit electric current can be blocked by the quick block of the second auxiliary bridge arm IGBT trigger pulses, without
DC Line Fault is cut off using AC circuit breaker.
Description of the drawings
Fig. 1 is the three-phase equivalent circuit of the present invention；
Fig. 2 is the equivalent circuit of the present invention；
Fig. 3 is the one equivalent circuit of exchange side of the present invention；
Fig. 4 is the one equivalent circuit of DC side of the present invention；
Fig. 5 is the control for adjusting the Feedforward Decoupling closed-loop control for realizing watt current and reactive current in the present invention by PI
Tactful block diagram；
Fig. 6 is that outer shroud control strategy uses power and voltage-controlled control strategy block diagram in the present invention；
Fig. 7 is the control strategy block diagram for adjusting the closed-loop control for realizing average anode current in the present invention by PI；
Fig. 8 is the DC voltage perseverance for using the pi regulator of voltage close loop to control each submodule in main bridge arm in the present invention
Fixed control strategy block diagram；
Fig. 9 is to assist bridge arm voltage V to DC side in the present inventiona1、Vb2、Vc3In contain DC voltage component VbloIt is controlled
The control strategy block diagram of system；
Bridge arm modulating wave schematic diagram when Figure 10 is the more level HVDC transverter steady-state operations of Three phase serial module structureization；
Figure 11 be k=1 when the present invention in exchange side voltage and current oscillogram；
Figure 12 be k=1 when the present invention in DC voltage electric current oscillogram；
Figure 13 be k=1 when the present invention in transmitting active power and reactive power oscillogram；
Figure 14 be k=1 when the present invention in main bridge arm and auxiliary bridge arm DC capacitor voltage oscillogram；
Figure 15 be k=1 when the present invention in ac-side current spectrum analysis figure；
Figure 16 be k=1 when the present invention in DC side electric current spectrum analysis figure；
Exchange side assists the oscillogram of bridge arm modulating wave in the present invention when Figure 17 is k=1；
DC side assists the oscillogram of bridge arm modulating wave in the present invention when Figure 18 is k=1；
Figure 19 be k=1 when the present invention in main bridge arm modulating wave oscillogram；
Figure 20 be k=0.6 when the present invention in exchange side voltage and current oscillogram；
Figure 21 be k=0.6 when the present invention in DC voltage electric current oscillogram；
Figure 22 be k=0.6 when the present invention in transmitting active power and reactive power oscillogram；
Figure 23 be k=0.6 when the present invention in main bridge arm and auxiliary bridge arm DC capacitor voltage oscillogram；
Figure 24 be k=0.6 when the present invention in ac-side current spectrum analysis figure；
Figure 25 be k=0.6 when the present invention in DC side electric current spectrum analysis figure；
Exchange side assists the oscillogram of bridge arm modulating wave in the present invention when Figure 26 is k=0.6；
DC side assists the oscillogram of bridge arm modulating wave in the present invention when Figure 27 is k=0.6；
Figure 28 be k=0.6 when the present invention in main bridge arm modulating wave oscillogram；
Figure 29 is the circuit diagram of the present invention.
Specific implementation mode
The present invention is described in further detail below in conjunction with the accompanying drawings：
With reference to figure 29, the more level HVDC transverters of Three phase serial module structureization of the present invention include direct current output
End, three-phase alternating current input terminal, the first transformer T1, the second transformer T2, third transformer T3, the first single-phase converter, second
Single-phase converter and third single-phase converter, wherein three output ends of three-phase alternating current input terminal respectively with the first transformer T1
In one end of middle primary coil, the second transformer T2 in one end of primary coil and third transformer T3 primary coil one end phase
Connection, in the first transformer T1 in the other end of primary coil, the second transformer T2 primary coil the other end and third transformation
The other end of primary coil is connected in device T3, secondary in one end of secondary coil, the second transformer T2 in the first transformer T1
In one end of coil and third transformer T3 one end of secondary coil respectively with the first auxiliary bridge arm in the first single-phase converter
The first auxiliary bridge arm w3 in the first auxiliary bridge arm v2 and third single-phase converter in u1, the second single-phase converter is connected；
The second auxiliary bridge arm a1 in first single-phase converter is connected with the anode of DC output end, the master in the first single-phase converter
Bridge arm 1b is connected with the second auxiliary bridge arm b2 in the other end and the second single-phase converter of secondary coil in the first transformer T1
It connects, the other end and third single-phase converter of secondary coil in the main bridge arm 2c and the second transformer T2 in the second single-phase converter
In third auxiliary bridge arm c3 be connected, secondary coil in the main bridge arm 3d in third single-phase converter and third transformer T3
The cathode of the other end and DC output end is connected；The second auxiliary bridge arm a1 in first single-phase converter, the second single-phase unsteady flow
The second auxiliary bridge arm c3 in the second auxiliary bridge arm b2 and third single-phase converter in device is by n/2 full-bridge submodule, the
One inductance and first resistor are sequentially connected in series, and n is the even number more than or equal to 2.
The first auxiliary bridge arm u1 and main bridge arm 1b compositions in the secondary coil of first transformer T1, the first single-phase converter
First exchange side loop, secondary coil, the first auxiliary bridge arm v2 in the second single-phase converter and the main bridge of the second transformer T2
Arm 2c composition the second exchange side loop, the first auxiliary bridge arm in the secondary coil of third transformer T3, third single-phase converter
W3 and main bridge arm 3d composition thirds exchange side loop, wherein the interior circular current of the first exchange side loop, the second exchange side loop
Interior circular current and third exchange side loop interior circular current be all made of the active and reactive current feed-forward decoupling control method of exchange side into
Row control, first, which exchanges the main bridge arm 1b in side loop, the main bridge arm 2c in the second exchange side loop and third, exchanges side loop
In main bridge arm 3d be all made of and determine active power and determine alternating voltage control method to be controlled, the in the first exchange side loop
The first auxiliary bridge arm in one auxiliary bridge arm u1, the first auxiliary bridge arm v2 in the second exchange side loop and third exchange side loop
The constant DC voltage control method that w3 is all made of current oriention is controlled.
Reactive power distribution coefficient k is introduced, realizes reactive power in the first exchange by adjusting reactive power distribution coefficient k
Distribution in side loop between the auxiliary of main bridge arm 1b and first bridge arm u1, second exchanges main bridge arm 2c and first in side loop and assist
Distribution in distribution and third exchange side loop between bridge arm v2 between the auxiliary bridge arms of main bridge arm 3d and first w3.
The second auxiliary bridge arm a1 and main bridge arm 1b in first single-phase converter forms the first DC circuit, the second single-phase change
The the second auxiliary bridge arm b2 and main bridge arm 2c flowed in device forms the second DC circuit, the second service bridge in third single-phase converter
Arm c3 and main bridge arm 3d forms third DC circuit, wherein in the interior circular current, the second DC circuit in the first DC circuit
Interior circular current in interior circular current and third DC circuit is controlled by the feedforward closed loop control method of DC current, the
The main bridge arm 2c in main bridge arm 1b, the second DC circuit in one DC circuit and the main bridge arm 3d in third DC circuit pass through
Determine DC voltage to be controlled, the second service bridge in the second auxiliary bridge arm a1, the second DC circuit in the first DC circuit
The second auxiliary bridge arm c3 in arm b2 and third DC circuit passes through constant DC voltage control.
The main bridge arm 2c and third single-phase converter in main bridge arm 1b, the second single-phase converter in first single-phase converter
In main bridge arm 3d be sequentially connected in series by n half-bridge submodule；The first auxiliary bridge arm u1 in first single-phase converter, the
In two single-phase converters first auxiliary bridge arm v2 and third single-phase converter in first auxiliary bridge arm w3 by second resistance,
Second inductance and n/2 half-bridge submodule are sequentially connected in series.
According to the requirement of input and output voltage amplitude and system transmission power, the present invention can flexibly select bridge arm submodule
The number and parameter of block, are modulated in normal operation by the submodule to each bridge arm, make bridge arm output relevant voltage with
Realize the control targe of AC and DC side.For convenience of the mathematical modeling of the present invention, n half-bridge submodule, friendship in main bridge arm
N/2 full-bridge submodule in n/2 half-bridge submodule and exchange side auxiliary bridge arm in the auxiliary bridge arm of stream side can be equivalent to
Controlled voltage source, thus equivalent-circuit model of the invention is as shown in Figure 1.
According to kirchhoff Circuit Theorem, loop-voltage equation of the invention is obtained by Fig. 1 and node current equation is as follows：
Use the transformation matrix of constant power transformation β o from abc to α for Cabc/αβo, wherein
It is C by the transformation matrix of α β o to abcαβo/abcFor：
By constant power transformation matrix Cabc/αβoPremultiplication formula (1)~formula (3), obtain voltage equation of the system under α β coordinate systems and
Current equation is：
Wherein, Vsα、Vsβ、VsoAnd isα、isβ、isoFor the α β o components of exchange side voltage and current；Vlα、Vlβ、VloAnd ilα、
ilβ、iloFor the α β o components of three voltage and currents of DC side；Vbsα、Vbsβ、VbsoO points of the α β of bridge arm voltage are assisted for exchange side
Amount；Vblα、Vblβ、VbloThe α β o components of bridge arm voltage are assisted for DC side；Vbcα、Vbcβ、VbcoAnd ibcα、ibcβ、ibcoFor main bridge arm
The α β o components of voltage and current.
If synchronous rotating angle matrix is：
Formula (6)-formula (8) is transformed to by the voltage equation under dqo coordinate systems and current equation using formula (9) and formula (10)
It is as follows：
If AC input voltage is three-phase symmetrical, i.e. Vso=0, in addition, due to ia=ib=ic, it is known that ilα=ilβ=0,
ild=ilq=0；Then formula (11)-formula (13) is converted to：
Wherein, formula (14)-formula (16) is mathematical model of the present invention under dqo coordinate systems, which is 4 rank moulds
Type.
In the application of HVDC systems, the control strategy of converting plant is different from the control strategy of Inverter Station.With traditional LC C-
HVDC control system is similar, and converting plant uses constant dc power control, Inverter Station to use constant DC voltage control, below will be with converting plant
For carry out control strategy research.
Now consider an equivalent circuit of the more level HVDC transverters of Three phase serial module structureization, as shown in Figure 2.
Using principle of stacking, one equivalent circuit of exchange side is as shown in Figure 3.
By mathematical modulo pattern (14) of the present invention under dqo coordinate systems it is found that having to make exchange side input current not include
DC component enables Vbso=-Vbmo；When converting plant straight-flow system voltage is DC voltage VdcWhen, it obtainsFor direct current,
There is AC compounent to make DC side output current not include, V can be enabledblo+VbmoIn do not include AC compounent；Meanwhile it is every to realize
A single-phase inverters export DC voltage, enable DC side auxiliary bridge arm voltage Vbld=-Vbmd, Vblq=-Vbmq。
When systematic steady state is run, of the invention three main bridge arms are for realizing alternating current-direct current power conversion, therefore main bridge arm is electric
Press V1b、V2c、V3dWith electric current i1b、i2c、i3dInclude AC-frequency component and DC component.But due to exchange side and DC side
The DC side of auxiliary bridge arm does not have burden with power, therefore in the case where not considering active loss, cannot absorb or send out
Active power.Due to exchange side auxiliary bridge arm current iu1、iv2、iw3For simple sinusoidal alternating current, DC component is not contained, therefore hand over
Flow side auxiliary bridge arm voltage Vu1、Vv2、Vw3In should only contain DC voltage component, and AC-frequency component cannot be contained, i.e. Vbsd
=Vbsq=0,Due to DC side auxiliary bridge arm current ia1、ib2、ic3For DC current, do not contain
AC compounent, therefore DC side auxiliary bridge arm voltage Va1、Vb2、Vc3In should only contain AC-frequency component, i.e. Vblo=0.
When systematic steady state is run, had by two formulas before formula (14)：
Auxiliary bridge arm and the active power and reactive power of the total coabsorption of main bridge arm are respectively
To ensure that the active power that auxiliary bridge arm absorbs is zero, then have：
Vbsdisd+Vbsqisq=0 (19)
To realize the dynamic allocation of absorbing reactive power ratio between auxiliary bridge arm and main bridge arm, reactive power distribution system is introduced
Number k so that main bridge arm absorbing reactive power meets：
kQbs=Vbmqisd-Vbmdisq (20)
I.e. as k=1, reactive power is all absorbed by main bridge arm.
Simultaneous formula (18)-formula (20), then have：
Solution formula (21), obtains
In practical operation, the active power that auxiliary bridge arm absorbs not is 0, it needs to absorb a small amount of active power to mend
The active loss in bridge arm is repaid, submodule DC capacitor continuous discharge in the block is avoided, to ensure that DC voltage is constant.If auxiliary
The active power that bridge arm absorbs is Pbs_loss, therefore constraint equation (19) is rewritten as
Vbsdisd+Vbsqisq=Pbs_loss (24)
Association type (18), formula (20) and formula (24), then have：
Solution formula (25), obtains
Control strategy is represented by structure chart control as follows shown in formula (26) and formula (27), wherein exchange side service bridge
The active-power P that arm absorbsbs_lossIt is generated by auxiliary bridge arm DC voltage outer shroud.
Control strategy
(1) exchange side control strategy
The mathematical model of the present invention is similar to traditional mathematical model of grid-connected transverter, using based on grid voltage orientation
Feed forward decoupling control strategy it is as follows：
Before formula (14) in two formulas, enable
The Feedforward Decoupling closed-loop control for realizing watt current and reactive current is adjusted by PI, wherein Vbd' and Vbq' by electricity
The pi regulator of stream closed loop obtains, and control principle is as shown in Figure 5.
The outer shroud control strategy of the present invention is controlled using power and voltage, i.e., for exchange side system using fixed active
Power is controlled with alternating voltage is determined, as shown in Figure 6.
(2) DC side control strategy
The DC voltage of each submodule is constant in main bridge arm of the invention in order to control, by controlling Vblo+VbmoIt realizes.When
Converting plant straight-flow system voltage is DC voltage VdcWhen, it obtainsBy mathematical modulo of the present invention under dqo coordinate systems
The close-loop control scheme of the third formula of pattern (15), design voltage outer shroud and current inner loop is as follows.
It is obtained by the third formula of formula (15)
It enables
The closed-loop control for realizing average anode current can be then adjusted by PI.Wherein, Vbo' adjusted by the PI of current closed-loop
Device obtains, and control principle is as shown in Figure 7.
Current setting value ilo *It is each in main bridge arm of the invention in order to control for the setting value of system dc side output current
The DC voltage of submodule is constant, using the pi regulator of voltage close loop, such as Fig. 8.
It actually is constantly present active loss in DC side auxiliary bridge arm, in order to ensure that DC side assists the direct current of bridge arm
Voltage constant, it is also necessary to DC side auxiliary bridge arm voltage Va1、Vb2、Vc3In contain DC voltage component VbloIt is controlled.And
VbloThe DC voltage closed loop of each submodule of bridge arm can be assisted to generate by DC side.And then V can be obtained by formula (31)bmo, control structure
It can indicate as shown in Figure 9.
Systematic steady state value calculates
If AC system is three-phase symmetrical system.Without loss of generality, it is assumed that input-output system when steady operation of the present invention
Voltage and current be：
Steady state solution of the invention is obtained using previously described constant power transformation matrix and synchronous rotating angle matrix
For：
Further
Each bridge arm modulation degree distribution schematic diagram is as shown in Figure 7 when stable state, wherein the modulation degree of exchange side auxiliary bridge arm is
m1-2m3, it is -2m that DC side, which assists the modulation degree of bridge arm,2, the modulation degree of main bridge arm is m2+m3。
In steady-state operation of the present invention, to make main bridge arm and auxiliary bridge arm only modulate, to maximize transverter and hand over
Stream and DC side systems exchange active and reactive power, set optimization aim as：
The power attenuation P of auxiliary bridge arm can be ignored when systematic steady statebs_loss, obtained by formula (22)~(23)：
Formula (22)~(23) are substituted into formula (41)~(43), are obtained
By formula (44)~(46), the value by adjusting k is the stable state modulation degree that main bridge arm can be changed and assist bridge arm, in turn
The optimal value for the k for meeting optimization aim formula (40) is calculated, to be optimized to the overall performance of system.
Simulation study
The system model of the present invention is built under MATLAB/SIMULINK platforms, system major parameter is as shown in table 1.
The more level HVDC Converter DC-sides voltage electricity of Three phase serial module structureization when Figure 11-Figure 19 is respectively k=1
Flow oscillogram, exchange side voltage and current waveform, the active power of transmission and reactive power oscillogram, main bridge arm and auxiliary bridge arm
DC capacitor voltage oscillogram, ac-side current spectrum analysis figure, DC side current spectrum analysis chart, exchange side assist bridge arm tune
Wave oscillogram processed, DC side auxiliary bridge arm modulating wave oscillogram, main bridge arm modulating wave oscillogram.
The more level HVDC transverters exchange side voltages of Three phase serial module structureization when Figure 20-Figure 28 is respectively k=0.6
Current waveform figure, DC voltage current waveform figure, transmission active power and reactive power oscillogram, main bridge arm and auxiliary bridge arm
DC capacitor voltage oscillogram, ac-side current spectrum analysis figure, DC side current spectrum analysis chart, exchange side assist bridge arm tune
Wave oscillogram processed, DC side auxiliary bridge arm modulating wave oscillogram, main bridge arm modulating wave oscillogram.
Claims (5)
1. a kind of more level HVDC transverters of Three phase serial module structureization, which is characterized in that including DC output end, three intersections
Flow input terminal, the first transformer (T1), the second transformer (T2), third transformer (T3), the first single-phase converter, second single-phase
Current transformer and third single-phase converter, wherein three output ends of three-phase alternating current input terminal respectively in the first transformer (T1)
In one end of primary coil, the second transformer (T2) in one end of primary coil and third transformer (T3) primary coil one end
It is connected, the other end of primary coil and in the other end of primary coil, the second transformer (T2) in the first transformer (T1)
The other end of primary coil is connected in three transformers (T3), one end of secondary coil, the second transformation in the first transformer (T1)
In device (T2) in one end of secondary coil and third transformer (T3) one end of secondary coil respectively in the first single-phase converter
The first auxiliary bridge arm (u1), the first auxiliary bridge arm (v2) in the second single-phase converter and first in third single-phase converter
Auxiliary bridge arm (w3) is connected；
The second auxiliary bridge arm (a1) in first single-phase converter is connected with the anode of DC output end, the first single-phase converter
In main bridge arm (1b) and the first transformer (T1) in secondary coil the other end and the second auxiliary in the second single-phase converter
Bridge arm (b2) is connected, the other end of the main bridge arm (2c) in the second single-phase converter and secondary coil in the second transformer (T2)
And the third auxiliary bridge arm (c3) in third single-phase converter is connected, the main bridge arm (3d) in third single-phase converter and third
The other end of secondary coil and the cathode of DC output end are connected in transformer (T3)；
The second auxiliary bridge arm (a1) in first single-phase converter, the second auxiliary bridge arm (b2) in the second single-phase converter and the
The second auxiliary bridge arm (c3) in three single-phase converters is gone here and there successively by n/2 full-bridge submodule, the first inductance and first resistor
Join, n is the even number more than or equal to 2；
First auxiliary bridge arm (u1) and main bridge arm (1b) group in the secondary coil of first transformer (T1), the first single-phase converter
At the first exchange side loop, the first auxiliary bridge arm (v2) in the secondary coil of the second transformer (T2), the second single-phase converter
And main bridge arm (2c) composition the second exchange side loop, the in the secondary coil of third transformer (T3), third single-phase converter
One auxiliary bridge arm (w3) and main bridge arm (3d) composition third exchange side loop, wherein the interior circular current of the first exchange side loop, the
The interior circular current of two exchange side loops and the interior circular current of third exchange side loop are all made of the active and reactive current feed-forward of exchange side
Decoupling control method is controlled, the main bridge arm in main bridge arm (1b), the second exchange side loop in the first exchange side loop
Main bridge arm (3d) in (2c) and third exchange side loop, which is all made of, to be determined active power and determines alternating voltage control method to be controlled
System, the first auxiliary bridge arm (u1) in the first exchange side loop, the first auxiliary bridge arm (v2) and the in the second exchange side loop
The constant DC voltage control method that the first auxiliary bridge arm (w3) in three exchange side loops is all made of current oriention is controlled.
2. the more level HVDC transverters of Three phase serial module structureization according to claim 1, which is characterized in that introduce nothing
Work(power partition coefficient k realizes reactive power main bridge arm in the first exchange side loop by adjusting reactive power distribution coefficient k
Distribution between (1b) and the first auxiliary bridge arm (u1), second exchanges main bridge arm (2c) in side loop and assist bridge arm (v2) with first
Between distribution and third exchange side loop in main bridge arm (3d) distribution between bridge arm (w3) is assisted with first.
3. the more level HVDC transverters of Three phase serial module structureization according to claim 1, which is characterized in that first is single
The second auxiliary bridge arm (a1) and main bridge arm (1b) in phase current transformer form the first DC circuit, and the in the second single-phase converter
Two auxiliary bridge arms (b2) and main bridge arm (2c) form the second DC circuit, the second auxiliary bridge arm (c3) in third single-phase converter
And main bridge arm (3d) forms third DC circuit, wherein interior in the interior circular current, the second DC circuit in the first DC circuit
Interior circular current in circular current and third DC circuit is controlled by the feedforward closed loop control method of DC current, and first
The main bridge arm (2c) in main bridge arm (1b), the second DC circuit in DC circuit and the main bridge arm (3d) in third DC circuit
It is controlled by determining DC voltage, second in the second auxiliary bridge arm (a1), the second DC circuit in the first DC circuit
The second auxiliary bridge arm (c3) in auxiliary bridge arm (b2) and third DC circuit passes through constant DC voltage control.
4. the more level HVDC transverters of Three phase serial module structureization according to claim 1, which is characterized in that first is single
The main bridge arm (2c) in main bridge arm (1b), the second single-phase converter in phase current transformer and the main bridge arm in third single-phase converter
(3d) is sequentially connected in series by n half-bridge submodule.
5. the more level HVDC transverters of Three phase serial module structureization according to claim 1, which is characterized in that first is single
The the first auxiliary bridge arm (v2) and the single-phase unsteady flow of third in the first auxiliary bridge arm (u1), the second single-phase converter in phase current transformer
The first auxiliary bridge arm (w3) in device is sequentially connected in series by second resistance, the second inductance and n/2 half-bridge submodule.
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| CN103715875A (en) * | 2013-12-31 | 2014-04-09 | 华为技术有限公司 | Switching frequency adjusting method and device and inverters |
| CN103944433A (en) * | 2014-04-29 | 2014-07-23 | 华为技术有限公司 | Three-phase three-level inverter circuit and uninterruptible power supply |
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| CN103141018A (en) * | 2010-07-30 | 2013-06-05 | 阿尔斯通技术有限公司 | Hvdc converter comprising fullbridge cells for handling a DC side short circuit |
| CN103715875A (en) * | 2013-12-31 | 2014-04-09 | 华为技术有限公司 | Switching frequency adjusting method and device and inverters |
| CN103944433A (en) * | 2014-04-29 | 2014-07-23 | 华为技术有限公司 | Three-phase three-level inverter circuit and uninterruptible power supply |
| CN105305843A (en) * | 2015-10-13 | 2016-02-03 | 国网山东省电力公司聊城供电公司 | Three-phase series half H-bridge modular multilevel DC converter and control method thereof |
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