CN105490552B - A kind of solid-state transformer and control method based on MMC - Google Patents
A kind of solid-state transformer and control method based on MMC Download PDFInfo
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- CN105490552B CN105490552B CN201610017990.9A CN201610017990A CN105490552B CN 105490552 B CN105490552 B CN 105490552B CN 201610017990 A CN201610017990 A CN 201610017990A CN 105490552 B CN105490552 B CN 105490552B
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Abstract
The present invention provides a kind of solid-state transformer and control method based on MMC, and solid-state transformer includes hiigh pressure stage AC/DC converter, isolation level DC/DC converter and low-pressure stage DC/AC converter；Hiigh pressure stage AC/DC converter connects isolation level DC/DC converter by high voltage dc bus, and isolation level DC/DC converter connects low-pressure stage DC/AC converter by low-pressure stage DC bus parallel module.Present invention beginning mesolow grade DC side is by using this topological structure of DC bus crisscross parallel, to solve in structure, solid-state transformer high and low pressure side system is unbalanced to influence each other, improve automatically power supply reliability '；Mutual balance solid-state transformer based on MMC structure can be realized and influence and power grid of the three-phase imbalance load to power grid is inhibited influence of the asymmetrical three-phase to AC load occur by the constant of control hiigh pressure stage common DC bus voltage.
Description
Technical field
The invention belongs to power electronics fields, and in particular to a kind of solid-state transformer and controlling party based on MMC
Method.
Background technique
Solid-state transformer is also known as electric power electric transformer or flexible transformer, it is with electric electronic current change technology and electricity
Novel transformer based on magnetic induction technology, it thoroughly changes the system structure of traditional transformer, is realizing conventional electricity
On the basis of the basic functions such as power transformer voltage grade transformation, electrical isolation and energy transmission, bi-directional current can also be realized
Many additional functionalities such as control, utility power quality control are the critical equipments of next-generation smart grid construction.By power electronics member device
The limitation of part development level is adapted to high pressure, high-power, high current the solid-state transformation for meeting four quadrant running of power grid demand
Device must be by the way of all-controlling power electronics device series and parallel or more level.It is currently used to be suitable for high-power
The solid-state transformer main circuit topology of occasion is mainly based upon H bridge cascade connection type (such as Fig. 1), neutral point clamp type multilevel converter
Solid-state transformer, these topological structures have many advantages, such as, but there is also be not easy built modular, control complexity, required
The disadvantages of device is excessive, the solid-state transformer of such topological structure do not have the automatic mutual electric energy matter inhibited between power grid and load
Measure interference function.
Summary of the invention
In order to overcome the above-mentioned deficiencies of the prior art, the present invention provides a kind of solid-state transformer based on MMC and control
Method, the mutual balance solid-state transformer based on MMC structure can be real by the constant of control hiigh pressure stage common DC bus voltage
Influence and power grid of the three-phase imbalance load to power grid is now inhibited influence of the asymmetrical three-phase to AC load occur.
In order to achieve the above-mentioned object of the invention, the present invention adopts the following technical scheme that:
The present invention provides a kind of solid-state transformer based on MMC, and the solid-state transformer includes hiigh pressure stage AC/DC transformation
Device, isolation level DC/DC converter and low-pressure stage DC/AC converter；The hiigh pressure stage AC/DC converter passes through high voltage dc bus
Isolation level DC/DC converter is connected, the isolation level DC/DC converter connects low pressure by low-pressure stage DC bus parallel module
Grade DC/AC converter.
The hiigh pressure stage AC/DC converter uses MMC, to improve the voltage class of solid-state transformer input stage；
The submodule number of each phase element investment of hiigh pressure stage AC/DC inverter is 2M, upper bridge arm and lower bridge arm series connection
Submodule number is M, and each submodule with the single-phase full bridge DC/AC converter of isolation level high-pressure side DC/AC conversion module
It is connected by way of common DC capacitor, completes the transformation that high voltage direct current is pressed onto high-frequency ac square wave.
The isolation level DC/DC converter include isolation level high-pressure side DC/AC conversion module, isolation level high frequency transformer and
Isolation level low-pressure side AC/DC conversion module；
No-load voltage ratio is 2M:3, the output of isolation level low pressure between the primary side winding and vice-side winding of the isolation level high frequency transformer
The single-phase full bridge AC/DC module of side AC/DC conversion module connects low-pressure stage DC bus parallel module, completes high-frequency ac square wave
To the transformation of low-voltage dc voltage.
The low-pressure stage DC/AC converter by low-pressure stage DC bus parallel module and three independent controls single-phase full bridge
Inverter and corresponding LC filter composition, AC energy required for exporting realize voltage transformation, the electric energy of solid-state transformer
Transmission and utility power quality control.
The present invention also provides a kind of control method of solid-state transformer based on MMC, the control method includes following step
It is rapid:
Step 1: hiigh pressure stage AC/DC converter carries out the double-closed-loop control of voltage and current, loop current suppression control and submodule
Block capacitance voltage Balance route；
Step 2: isolation level DC/DC converter carries out between hiigh pressure stage AC/DC converter and low-pressure stage DC/AC converter
Electrical isolation and voltage class transformation control；
Step 3: low-pressure stage DC/AC converter carries out phase voltage virtual value constant control and realizes waveform sine.
In the step 1, hiigh pressure stage AC/DC converter using determine active power vector control method under dq coordinate system into
Double-closed-loop control, loop current suppression control and the submodule capacitor voltage Balance route of row voltage and current.
In the step 2, isolation level DC/DC converter using open loop control strategy carry out hiigh pressure stage AC/DC converter with
Electrical isolation and voltage class transformation control between low-pressure stage DC/AC converter.
The step 2 the following steps are included:
Step 2-1: the high-voltage dc voltage of hiigh pressure stage AC/DC converter output converts mould through isolation level high-pressure side DC/AC
Block is modulated into high-frequency ac square wave；
Step 2-2: high-frequency ac square wave is synchronized through isolation level high frequency transformer is coupled to isolation level low-pressure side AC/DC transformation
Module；
Step 2-3: the high-frequency ac square wave of isolation level low-pressure side AC/DC conversion module is coupled to through isolation level low-pressure side
AC/DC conversion module synchronous rectification is low-voltage dc voltage, and low-pressure stage DC/AC converter is given in output.
In the step 3, low-pressure stage DC/AC converter carries out the constant control of phase voltage virtual value using Double-loop Control Strategy
System, and realize waveform sine.
The step 3 the following steps are included:
Step 3-1: it in outer ring control strategy, first passes through phase voltage instantaneous value and obtains practical phase voltage virtual value, then
Phase voltage virtual value is compared with phase voltage command value, obtained deviation after PI controller with standard sine signal phase
Multiply, the instruction value as phase voltage instantaneous value in inner loop control strategy；
Step 3-2: in inner ring control strategy, first by the instruction value of the phase voltage instantaneous value exported in outer loop control strategy
Compared with the practical phase voltage instantaneous value of feedback, then its margin of error is believed after proportional controller as modulating wave instruction
Number, finally and by the modulating wave command signal compared with triangle carrier signal, pulse triggering signal is formed to trigger power switch
Device correctly acts.
Compared with prior art, the beneficial effects of the present invention are:
1) MMC circuit has high modularization, and the submodule number that investment inverter is adjusted flexibly can meet difference
Other multilevel converters are compared in the requirement of power and different voltages grade, have apparent advantage in hardware topology；
2) different from the topology of tradition VSC, string has bridge arm reactor in each bridge arm of MMC, and bridge arm reactor can press down
Make DC voltage instantaneous value as each phase element in parallel it is not exactly the same and caused by alternate circulation, while can also effectively reduce
The climbing of fault current when DC bus breaks down inhibits dash current, improves the reliability of system；
3) low-pressure stage DC side is by using this topological structure of DC bus crisscross parallel, to solve in structure
Solid-state transformer high and low pressure side system is unbalanced to influence each other, improve automatically power supply reliability '
4) the mutual balance solid-state transformer based on MMC structure can pass through the perseverance of control hiigh pressure stage common DC bus voltage
It is fixed, it realizes and influence and power grid of the three-phase imbalance load to power grid is inhibited influence of the asymmetrical three-phase to AC load occur.
Detailed description of the invention
Fig. 1 is in the prior art based on H bridge cascade connection type solid-state transformer main circuit topological structure figure；
Fig. 2 is the solid-state transformer main circuit topological structure figure in the embodiment of the present invention based on MMC；
Fig. 3 is mesolow grade DC bus wiring diagram of the embodiment of the present invention；
Fig. 4 is MMC main circuit topological structure figure in the embodiment of the present invention；
Fig. 5 is MMC Neutron module topology diagram in the embodiment of the present invention；
Fig. 6 is mesohigh grade AC/DC convertor controls policy map of the embodiment of the present invention；
Fig. 7 is capacitance voltage Balance route block diagram in the embodiment of the present invention；
Fig. 8 is isolation level DC/DC convertor controls block diagram in the embodiment of the present invention；
Fig. 9 is mesolow grade DC/AC convertor controls plan figure of the embodiment of the present invention.
Specific embodiment
The present invention is described in further detail below in conjunction with the accompanying drawings.
The present invention can not adapt to high-power distribution system for current solid-state transformer, and power grid cannot be inhibited to go out
When existing three-phase alternating current is asymmetric and threephase load imbalance between input and output side the problems such as influencing each other, propose a kind of base
It, can be by adjusting the constant of MMC converter high pressure common DC bus voltage, to press down in the solid-state transformer of MMC converter
There is influence of the asymmetrical three-phase to AC load, also, MMC in influence and power grid of the three-phase imbalance load processed to power grid
Inverter topological structure has high modularization, and the sub-series number of modules by the way that investment is adjusted flexibly can meet different function
The demand of rate and different voltages grade occasion.And the constant and low-pressure stage of adjusting high pressure common DC bus voltage can be passed through
DC side uses this topological structure of DC bus crisscross parallel, even if so that solid-state transformer be made three-phase alternating current occur in power grid
Stable operation is also able to achieve in the case of asymmetric or three-phase imbalance load.
A kind of solid-state transformer and control method being based on modularization multi-level converter (MMC) provided by the invention,
The hiigh pressure stage AC/DC converter of the solid-state transformer improves the voltage class of solid-state transformer input stage using MMC inverter,
Low-pressure stage DC side realizes the automatic mutual equilibrium function of solid-state transformer by DC bus parallel module.This patent design
Solid-state transformer based on MMC inverter can be by adjusting the constant of high pressure common DC bus voltage, to realize inhibition three
There is influence of the asymmetrical three-phase to AC load, also, the MMC change of current in influence and power grid of the phase uncompensated load to power grid
Device topological structure have high modularization, the sub-series number of modules by the way that investment is adjusted flexibly can meet different capacity and
The demand of different voltages grade occasion, compared to other multilevel converters, in hardware topology have apparent advantage.Separately
Outside, low-pressure stage DC side uses this topological structure of DC bus crisscross parallel, to solve solid-state transformer in structure
High and low pressure side system is unbalanced to influence each other, and improves power supply reliability automatically, the energy as long as a submodule normal operation
Guarantee basic electricity, and its simple structure, convenient control, this is also that the solid-state transformer of the invention designed can be realized automatically
The key point of mutual equilibrium function.Solid-state transformer is a kind of by Technics of Power Electronic Conversion technology and based on the electricity of electromagnetic induction principle
Energy switching technology combines, and realizes the power equipment that a kind of electric energy of electrical nature is changed into another electrical nature.It is tying
On structure, it includes two fundamentals: converters and high frequency transformer, and wherein converters include main electricity
Road part and control circuit part；High frequency transformer realizes the link of two sides converters, and major function is to realize
Electrical isolation and voltage class transformation, frequency are usually operated at kHz (kHz) rank, and the purpose of high frequency mainly substantially contracts
The volume of small transformers mitigates weight, reduces heat dissipation and improves transformer capacity and efficiency etc..
The present invention provides a kind of solid-state transformer based on MMC, such as Fig. 2, and the solid-state transformer includes hiigh pressure stage AC/DC
Converter, isolation level DC/DC converter and low-pressure stage DC/AC converter；The hiigh pressure stage AC/DC converter passes through high voltage direct current
Bus connects isolation level DC/DC converter, and the isolation level DC/DC converter is connected by low-pressure stage DC bus parallel module
Low-pressure stage DC/AC converter.
The hiigh pressure stage AC/DC converter uses MMC, to improve the voltage class of solid-state transformer input stage；
The submodule number of each phase element investment of hiigh pressure stage AC/DC inverter is 2M, upper bridge arm and lower bridge arm series connection
Submodule number is M, and each submodule with the single-phase full bridge DC/AC converter of isolation level high-pressure side DC/AC conversion module
It is connected by way of common DC capacitor, completes the transformation that high voltage direct current is pressed onto high-frequency ac square wave.
Low-pressure stage DC bus parallel module wiring diagram is as shown in Fig. 3,3 single-phase full bridge current transformers of isolation level low-pressure side
The direct current output DC of moduleAi、DCBi、DCCi(i=1,2,3) is accordingly connected in parallel, and forms solid-state transformer low-pressure stage 3
The DC bus DC of single-phase full bridge inverter modulea、DCb、DCc.The great advantage of this low-pressure side DC bus crisscross parallel be from
It solves that solid-state transformer high and low pressure side system is unbalanced to influence each other in structure, and improves power supply reliability automatically,
As long as a submodule normal operation is it is ensured that basic electricity, and its simple structure, convenient control, this is also that this patent is set
The solid-state transformer of meter can be realized the key point of automatic mutual equilibrium function.
The main circuit topological structure of modularization multi-level converter (MMC) is as shown in Fig. 4, wherein Fig. 4 is three-phase MMC
The main circuit topology of inverter is mainly composed in parallel by tri- phase elements of A, B, C, and each phase element includes upper and lower two bridge arm lists
Member, upper and lower bridge arm unit are composed in series by M identical submodules and a bridge arm reactor.Wherein, bridge arm reactor
Effect be inhibit the DC voltage instantaneous value as each phase element in parallel not exactly the same and caused by alternate circulation, while can also
The climbing of fault current when DC bus breaks down is effectively reduced, inhibits dash current, to improve the reliability of system.
Fig. 5 is the main circuit topological structure of submodule, wherein j=p, n；K=1,2...M；Z=a, b, c.Mainly controllably opened by two
Device and anti-paralleled diode and a DC energy storage capacitor composition are closed, wherein K1 is high speed by-pass switch, mainly there are two aspects
Effect: first is that when group inside modules break down, such as the damage of IGBT, K1 closure bypass failure submodule, so that MMC need not
For single submodule failure and shut down interruption；Second is that redundancy submodule is provided for MMC, when faulty submodule is bypassed
When, redundancy submodule is devoted oneself to work, and the reliability of system is improved.K2 is that compression joint type encapsulates thyristor, its main feature is that allowing to lead to
Biggish electric current is crossed, when short trouble occurs for MMC DC side, lockout switch device, next conducting K2 make three-phase first
Fault current more flow through K2, protect antiparallel diode, enhance the fault-resistant ability of system.
The isolation level DC/DC converter include isolation level high-pressure side DC/AC conversion module, isolation level high frequency transformer and
Isolation level low-pressure side AC/DC conversion module；
No-load voltage ratio is 2M:3, the output of isolation level low pressure between the primary side winding and vice-side winding of the isolation level high frequency transformer
The single-phase full bridge AC/DC module of side AC/DC conversion module connects low-pressure stage DC bus parallel module, completes high-frequency ac square wave
To the transformation of low-voltage dc voltage.
The low-pressure stage DC/AC converter by low-pressure stage DC bus parallel module and three independent controls single-phase full bridge
Inverter and corresponding LC filter composition, AC energy required for exporting realize voltage transformation, the electric energy of solid-state transformer
Transmission and utility power quality control.
The present invention also provides a kind of control method of solid-state transformer based on MMC, the control method includes following step
It is rapid:
Step 1: hiigh pressure stage AC/DC converter carries out the double-closed-loop control of voltage and current, loop current suppression control and submodule
Block capacitance voltage Balance route；
In the step 1, hiigh pressure stage AC/DC converter using determine active power vector control method under dq coordinate system into
Double-closed-loop control, loop current suppression control and the submodule capacitor voltage Balance route of row voltage and current, as shown in Figure 6 and Figure 7.
Wherein, the voltage and current double-loop control strategy under synchronous rotating frame is to realize AC input current
Sineization and unity power factor control；Submodule capacitor voltage Balance route is to realize and maintain high-pressure side DC bus electricity
Press each submodule DC capacitor voltage of constant and MMC circuit balanced；The effect of loop current suppression control is exported according to outer voltage
Active current command value carry out input current control.
The effect of power network current control ring is to carry out input current control according to the active current command value of outer voltage output
System, as shown in fig. 6, making three-phase AC/DC Inverter circuit inner ring (i using voltage feed-forward control decoupling controlGd、iGq) realize solution
Coupling, and grid disturbances can be eliminated.The output of input power network current ring obtains abc seat after constant power transformation matrix of coordinates
Mark is lower MMC inverter three-phase alternating current output voltage given value emfz.Wherein, udcFor MMC type solid-state transformer high-pressure side direct current
Bus voltage value；For high-pressure side DC bus-bar voltage reference value；LgAfter bridge arm inductance and grid side filter inductance；uGd
And uGqFor the d axis and q axis component of network voltage；iGdAnd iGqFor the d axis and q axis component of power network current；In outer voltage and electric current
Ring is all made of proportional integration (PI) control.
The loop current suppression control strategy block diagram that hiigh pressure stage AC/DC converter uses is as shown in fig. 6, solve three-phase bridge arm current
ipzAnd inzAverage value up to the upper and lower bridge arm circulation i of three-phasediffz.By two frequency multiplication rotating coordinate transformation matrix T ' of negative phase-sequenceabc/dq
Afterwards, d, q axis component i of upper and lower bridge arm circulation are obtainedcidAnd iciq, by the reference value of they and d, q collar streamWithIt compares
After relatively, by pi regulator, and 2 ω L are introducedr·icid2With 2 ω Lr·iciq2, to eliminate the coupling of the dq axis in MMC Circulation Model
, the reference value u of internal uneven pressure drop d, q axis component can be acquireddiffd2refAnd udiffq2ref.In order to reduce the big of circulation
It is small, it takesWithIt is zero.Upper and lower bridge arm submodule capacitor voltage reference value u is acquired respectively through formula (1), (2)pzWith
unz。
Wherein, ud0For high-pressure side DC bus-bar voltage initial value；
Two frequency multiplication rotating coordinate transformation matrix T ' of negative phase-sequenceabc/dqAre as follows:
The Balance route strategy of each submodule DC capacitor voltage of hiigh pressure stage AC/DC converter is using the balanced component of superposition
Method, control strategy block diagram are as shown in Figure 7.This method is after being superimposed pressure component in voltage reference signal, divided by each submodule
The respective capacitance voltage value of block, regenerates the modulating wave of each submodule.It is to make all submodules on each bridge arm that it, which controls purpose,
The capacitance voltage of block tracks its reference value.Controller uses digital ratio equation adjuster, controls each submodule capacitor voltage tracking electricity
Hold voltage given value, exports uv-jkzFor submodule capacitor voltage Balance route superposition amount.It can according to the working principle of submodule
Know, when bridge arm current is charging current, to keep each submodule capacitor voltage balanced, the lower submodule of Ying Zengjia voltage is thrown
The angle of incidence allows it to charge, therefore the superposition of submodule capacitor voltage Balance route is measured and is positive.Vice versa.Using phase-shifting carrier wave
Modulation strategy, the modulating wave of each submodule are compared hair wave with respective triangular carrier, generate trigger pulse.
In the step 2, isolation level DC/DC converter using open loop control strategy carry out hiigh pressure stage AC/DC converter with
Electrical isolation and voltage class transformation control between low-pressure stage DC/AC converter, as shown in Figure 8.Step 2 includes following step
It is rapid:
Step 2-1: the high-voltage dc voltage of hiigh pressure stage AC/DC converter output converts mould through isolation level high-pressure side DC/AC
Block is modulated into high-frequency ac square wave；
Step 2-2: high-frequency ac square wave is synchronized through isolation level high frequency transformer is coupled to isolation level low-pressure side AC/DC transformation
Module；
Step 2-3: the high-frequency ac square wave of isolation level low-pressure side AC/DC conversion module is coupled to through isolation level low-pressure side
AC/DC conversion module synchronous rectification is low-voltage dc voltage, and low-pressure stage DC/AC converter is given in output.
In the step 3, low-pressure stage DC/AC converter carries out the constant control of phase voltage virtual value using Double-loop Control Strategy
System, and realize waveform sine.
Step 3: low-pressure stage DC/AC converter carries out phase voltage virtual value constant control and realizes waveform sine, such as Fig. 9
Shown, outer ring is phase voltage virtual value control ring, keeps output voltage virtual value constant, and inner ring is phase voltage Instantaneous control
Ring maintains the good sine of output waveform so that phase voltage tracks given sine voltage.
The step 3 the following steps are included:
Step 3-1: it in outer ring control strategy, first passes through phase voltage instantaneous value and obtains practical phase voltage virtual value, then
Phase voltage virtual value is compared with phase voltage command value, obtained deviation after PI controller with standard sine signal phase
Multiply, the instruction value as phase voltage instantaneous value in inner loop control strategy；
Step 3-2: in inner ring control strategy, first by the instruction value of the phase voltage instantaneous value exported in outer loop control strategy
Compared with the practical phase voltage instantaneous value of feedback, then its margin of error is believed after proportional controller as modulating wave instruction
Number, finally and by the modulating wave command signal compared with triangle carrier signal, pulse triggering signal is formed to trigger power switch
Device correctly acts.
Theoretically, output voltage virtual value stable state indifference may be implemented by phase voltage virtual value outer loop control in output stage,
To guarantee that output voltage virtual value is constant when load variation or system are disturbed.And inner ring to output voltage instantaneous value into
Row control maintains the good sine of output waveform so that phase voltage tracks given sine voltage.
Finally it should be noted that: the above embodiments are merely illustrative of the technical scheme of the present invention and are not intended to be limiting thereof, institute
The those of ordinary skill in category field can still modify to a specific embodiment of the invention referring to above-described embodiment or
Equivalent replacement, these are applying for this pending hair without departing from any modification of spirit and scope of the invention or equivalent replacement
Within bright claims.
Claims (1)
1. a kind of control method of the solid-state transformer based on MMC, it is characterised in that: the solid-state transformer includes hiigh pressure stage
AC/DC converter, isolation level DC/DC converter and low-pressure stage DC/AC converter；The hiigh pressure stage AC/DC converter passes through height
DC bus is pressed to connect isolation level DC/DC converter, the isolation level DC/DC converter passes through low-pressure stage DC bus and gang mould
Block connects low-pressure stage DC/AC converter；
The hiigh pressure stage AC/DC converter uses MMC, to improve the voltage class of solid-state transformer input stage；
The submodule number of each phase element investment of hiigh pressure stage AC/DC inverter is 2M, upper bridge arm and lower bridge arm series connection submodule
Block number is M, and each submodule passes through with the single-phase full bridge DC/AC converter of isolation level high-pressure side DC/AC conversion module
The mode of common DC capacitor connects, and completes the transformation that high voltage direct current is pressed onto high-frequency ac square wave；
The isolation level DC/DC converter includes isolation level high-pressure side DC/AC conversion module, isolation level high frequency transformer and isolation
Grade low-pressure side AC/DC conversion module；
No-load voltage ratio is 2M:3, isolation level low pressure outlet side between the primary side winding and vice-side winding of the isolation level high frequency transformer
The single-phase full bridge AC/DC module of AC/DC conversion module connects low-pressure stage DC bus parallel module, completes high-frequency ac square wave and arrives
The transformation of low-voltage dc voltage；
The low-pressure stage DC/AC converter by low-pressure stage DC bus parallel module and three independent controls single-phase full bridge inversion
Device and corresponding LC filter composition, AC energy required for exporting realize voltage transformation, the electric energy transmission of solid-state transformer
And utility power quality control；
The control method the following steps are included:
Step 1: hiigh pressure stage AC/DC converter carries out the double-closed-loop control of voltage and current, loop current suppression control and submodule electricity
Hold voltage balance control；
Step 2: isolation level DC/DC converter carries out electrical between hiigh pressure stage AC/DC converter and low-pressure stage DC/AC converter
Isolation and voltage class transformation control；
Step 3: low-pressure stage DC/AC converter carries out phase voltage virtual value constant control and realizes waveform sine；
In the step 1, the use of hiigh pressure stage AC/DC converter determines active power vector control method and carries out electricity under dq coordinate system
The double-closed-loop control of pressure and electric current, loop current suppression control and submodule capacitor voltage Balance route；
In the step 2, isolation level DC/DC converter carries out hiigh pressure stage AC/DC converter and low pressure using open loop control strategy
Electrical isolation and voltage class transformation control between grade DC/AC converter；
The step 2 the following steps are included:
Step 2-1: the high-voltage dc voltage of hiigh pressure stage AC/DC converter output is through isolation level high-pressure side DC/AC conversion module tune
High-frequency ac square wave is made；
Step 2-2: high-frequency ac square wave is synchronized through isolation level high frequency transformer is coupled to isolation level low-pressure side AC/DC transformation mould
Block；
Step 2-3: the high-frequency ac square wave of isolation level low-pressure side AC/DC conversion module is coupled to through isolation level low-pressure side AC/DC
Conversion module synchronous rectification is low-voltage dc voltage, and low-pressure stage DC/AC converter is given in output；
In the step 3, low-pressure stage DC/AC converter carries out phase voltage virtual value constant control using Double-loop Control Strategy, and
Realize waveform sine；
The step 3 the following steps are included:
Step 3-1: it in outer ring control strategy, first passes through phase voltage instantaneous value and obtains practical phase voltage virtual value, then by phase
Voltage effective value is compared with phase voltage command value, obtained deviation after PI controller with standard sine signal multiplication,
Instruction value as phase voltage instantaneous value in inner loop control strategy；
Step 3-2: in inner ring control strategy, first by the instruction value of the phase voltage instantaneous value exported in outer loop control strategy and instead
The practical phase voltage instantaneous value of feedback compares, and then its margin of error is used as to modulating wave command signal after proportional controller, most
Afterwards and by the modulating wave command signal compared with triangle carrier signal, pulse triggering signal is formed to trigger device for power switching just
Positive motion is made.
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| CN201610017990.9A CN105490552B (en) | 2016-01-12 | 2016-01-12 | A kind of solid-state transformer and control method based on MMC |
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| CN201610017990.9A CN105490552B (en) | 2016-01-12 | 2016-01-12 | A kind of solid-state transformer and control method based on MMC |
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| CN105490552A CN105490552A (en) | 2016-04-13 |
| CN105490552B true CN105490552B (en) | 2019-08-16 |
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| CN106026685A (en) * | 2016-05-23 | 2016-10-12 | 清华大学 | Topological structure of three-phase power electronic transformer employing low-fluctuation DC bus capacitors |
| CN106452099A (en) * | 2016-10-10 | 2017-02-22 | 中国矿业大学(北京) | Novel connection method of three-phase cascade convertor and working mode during power supply or load fault |
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| CN109217695B (en) * | 2017-06-29 | 2020-09-04 | 中车株洲电力机车研究所有限公司 | Voltage-sharing control method of cascaded solid-state transformer |
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| CN109950923B (en) * | 2019-03-26 | 2020-12-11 | 国网北京市电力公司 | AC-AC conversion device, and method and device for connecting power grid |
| CN110112942B (en) * | 2019-04-22 | 2020-10-30 | 上海交通大学 | Control method for inhibiting capacitor voltage fluctuation in modular solid-state transformer |
| CN110336462B (en) * | 2019-06-19 | 2020-09-18 | 平高集团有限公司 | Direct-current power electronic transformer and control method and device thereof |
| CN111600494A (en) * | 2019-08-09 | 2020-08-28 | 青岛鼎信通讯股份有限公司 | Control method for improving running performance of power electronic transformer after redundancy |
| CN110829865B (en) * | 2019-11-07 | 2021-04-13 | 国网江苏省电力有限公司电力科学研究院 | Self-adaptive switching method, device and system suitable for power electronic transformer |
| CN111384718B (en) * | 2020-02-27 | 2022-11-18 | 华为数字能源技术有限公司 | Power supply device, power supply system and data center |
| CN111262425B (en) * | 2020-03-31 | 2021-03-09 | 安可达技术(苏州)有限公司 | Control system and method of staggered totem-pole power factor correction circuit |
| CN111817599A (en) * | 2020-07-16 | 2020-10-23 | 哈尔滨工业大学 | Multi-port electric energy router and control method thereof |
| CN112039314B (en) * | 2020-09-07 | 2021-08-03 | 华中科技大学 | Load current feedforward control strategy and system for MMC type power electronic transformer |
| CN112217407B (en) * | 2020-09-30 | 2022-05-24 | 阳光电源股份有限公司 | Cascade type multiport converter and three-phase medium-voltage input system |
| CN112953254A (en) * | 2021-03-29 | 2021-06-11 | 山东电工电气集团有限公司 | Three-phase power electronic transformer topology and control method thereof |
| CN113241962B (en) * | 2021-06-07 | 2023-11-28 | 昆明理工大学 | Power electronic transformer based on three-phase four-bridge arm MMC and control method thereof |
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