CN108258928A - Based on modular multi-level converter imbalance fault optimization method - Google Patents
Based on modular multi-level converter imbalance fault optimization method Download PDFInfo
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- CN108258928A CN108258928A CN201711351672.7A CN201711351672A CN108258928A CN 108258928 A CN108258928 A CN 108258928A CN 201711351672 A CN201711351672 A CN 201711351672A CN 108258928 A CN108258928 A CN 108258928A
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- reference value
- circulation
- mmc
- controller
- voltage
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Classifications
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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
- H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
- H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
- H02M7/48—Conversion 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
- H02M7/483—Converters with outputs that each can have more than two voltages levels
- H02M7/49—Combination of the output voltage waveforms of a plurality of converters
Abstract
The present invention relates to one kind based on modular multi-level converter imbalance fault optimization method, this method realizes that this method includes based on MMC circuit topological structures：It output current, the reference value of circulation is calculated by corresponding control algolithm and measures DC bus-bar voltage according to the MMC bridge arm models that are averaged；According to output current reference value, output current controller is input to, generates output voltage reference value；According to loop current reference value, it is inputted novel with zero sequence control function circulation controller, generation circulation voltage reference value；According to output voltage reference value, circulation voltage reference value and DC bus-bar voltage obtain the insertion coefficient of the upper and lower bridge arms of MMC, are input to MMC and complete control.Present invention improves over zero sequence circulation controllers to inhibit DC bus-bar voltage ripple, can effectively inhibit dc-link capacitance voltage ripple.
Description
Technical field
The present invention relates to electric power network technique fields more particularly to one kind to be based on modular multi-level converter imbalance fault
Optimization method.
Background technology
Modular multilevel converter (MMC) has modularized design, alternating current-direct current output waveform quality height, transmission capacity
Greatly, decoupled active and reactive control can be achieved, can be acknowledged as to weak pattern system or passive network power supply, high reliability
It is next-generation high-voltage converter device, but its system structure is extremely complex, MMC-HVDC systems are usually comprising hundreds of identical
Submodule and a considerable amount of Detection ＆ Controling links, therefore control system of the control system of MMC also than common current transformer is complicated
Much.
When MMC-HVDC systems encounter failure, such as unbalanced power supply failure, voltage wave can be generated on dc bus
Dynamic, DC bus-bar voltage ripple can be optimized by improving zero sequence circulation controller, and general zero sequence circulation controller can have
Effect inhibits dc bus ripple during unbalanced power supply, but it is excellent to system progress to be not bound with zero axle dc loop circuit controller
Change.
The zero sequence circulation controller of modular multi-level converter can be to a certain extent during existing imbalance fault
Reduce the fluctuation of DC bus-bar voltage, but effect is not ideal enough, DC bus-bar voltage ripple can be caused excessive to submodule electricity
Appearance damages.
Invention content
The present invention proposes that one kind based on modular multi-level converter imbalance fault optimization method, is not increasing hardware
In the case of cost, it is excessive to effectively reduce DC bus-bar voltage ripple for MMC zero sequence circulation controllers during optimization design imbalance
The problem of.
To achieve the above object, the invention is realized in this way, a kind of modular multilevel that is based on provided by the invention becomes
Device imbalance fault optimization method is flowed, the method is realized based on MMC circuit topological structures, the MMC circuit topological structures packet
It includes：Several phases are formed per mutually being connected by upper and lower bridge arm with inductance, and per mutually and on busbar, the upper and lower bridge arm per phase is by identical
N number of submodule of number is composed in series, and the described method comprises the following steps：
Output current, the reference value of circulation and measurement are calculated by corresponding control algolithm according to the MMC bridge arm models that are averaged
DC bus-bar voltage；
According to the output current reference value, output current controller is input to, generates output voltage reference value；
According to the loop current reference value, it is inputted novel with zero sequence control function circulation controller, generation ring
Flow voltage reference value；
According to the output voltage reference value, circulation voltage reference value and DC bus-bar voltage obtain the upper and lower bridges of MMC
The insertion coefficient of arm is input to MMC and completes control.
Wherein, output voltage reference value is calculated by output current controller, and circulation voltage reference value is by circulation
Controller is calculated.
Wherein, the circulation controller is novel zero sequence circulation controller.
The beneficial effects of the invention are as follows：
It is increased when the present invention is for unbalanced power supply using DC bus-bar voltage ripple caused by each sequence circulation controller
A kind of problem, it is proposed that novel zero sequence circulation controller.According to based on modular multi-level converter in D.C. high voltage transmission system
The working characteristics of system (MMC-HVDC) establishes dc bus dynamical equation, designs DC bus-bar voltage controller, improves zero sequence
Circulation controller inhibits DC bus-bar voltage ripple, can effectively inhibit dc-link capacitance voltage ripple.
Description of the drawings
Fig. 1 is that the present invention is based on modular multi-level converter imbalance fault optimization method flow diagrams；
Fig. 2 is MMC structure charts；
Fig. 3 is MMC half-bridge sub-modular structure figures；
Fig. 4 is MMC overall control block diagrams；
Fig. 5 is novel zero sequence circulation controller block diagram.
In order to make the purpose , technical scheme and advantage of the present invention be clearer, with reference to the accompanying drawings and embodiments,
The present invention will be described in further detail.
Specific embodiment
It should be appreciated that the specific embodiments described herein are merely illustrative of the present invention, it is not used to limit this hair
It is bright.
As shown in Figure 1, the present invention proposes one kind based on modular multi-level converter imbalance fault optimization method, institute
It states method to realize based on MMC circuit topological structures, the MMC circuit topological structures include：Several phases, per mutually by upper and lower bridge arm
It connects to be formed with inductance, per mutually and on busbar, the upper and lower bridge arm per phase is composed in series by equal number of N number of submodule,
It the described method comprises the following steps：
S1 calculates output current, the reference value of circulation simultaneously according to the MMC bridge arm models that are averaged by corresponding control algolithm
Measure DC bus-bar voltage；
S2 according to the output current reference value, is input to output current controller, generates output voltage reference
Value；
S3 according to the loop current reference value, is inputted novel with zero sequence control function circulation controller, production
Raw circulation voltage reference value；
S4, according to the output voltage reference value, it is upper and lower that circulation voltage reference value and DC bus-bar voltage obtain MMC
The insertion coefficient of bridge arm is input to MMC and completes control.
Wherein, output voltage reference valueIt is to be calculated by output current controller, circulation voltage reference valueBe by
Circulation controller is calculated.
Specifically, using DC bus-bar voltage line caused by each sequence circulation controller when the present invention is for unbalanced power supply
A kind of the problem of wave increases, it is proposed that novel zero sequence circulation controller.According to based on modular multi-level converter in high straightening
The working characteristics of stream transmission system (MMC-HVDC) establishes dc bus dynamical equation, designs DC bus-bar voltage controller, changes
Inhibit DC bus-bar voltage ripple into zero sequence circulation controller, can effectively inhibit dc-link capacitance voltage ripple.
The zero sequence circulation controller of modular multi-level converter can be to a certain extent during existing imbalance fault
Reduce the fluctuation of DC bus-bar voltage, but effect is not ideal enough, DC bus-bar voltage ripple can be caused excessive to submodule electricity
Appearance damages.The present invention is not in the case where increasing hardware cost, MMC zero sequences circulation control when optimization design is uneven
Device effectively reduces the problem of DC bus-bar voltage ripple is excessive.
As shown in Fig. 2, Fig. 2 is MMC circuit topology figures, output staircase waveform analog sine can be achieved in this seed module topology.
In figure, upper and lower bridge arm connects to form a phase with inductance, and per mutually and on busbar, the upper and lower bridge arm per phase is by equal number of N
A sub- block coupled in series composition, can be according to actual conditions unrestricted choice submodule number, under normal circumstances in addition to the son of normal work
It is next spare also to have redundancy submodule for module.Exchange output is drawn from two symmetrical bridge arm inductance.
For submodule there are many structure, one of the most common structure is half-bridge module, and the half-bridge submodular circuits in Fig. 3 are opened up
It flutters, IGBT series connection formation half-bridge submodule topology in parallel with capacitance, IGBT carries anti-paralleled diode.On in half-bridge submodule
The drive waveforms of lower IGBT are complementary, and half-bridge structure output valve is in 0 and vcapBetween staggeredly convert.There are three types of states altogether for submodule：It is other
Road, insertion and locking.Bypass condition refers to that through on-off action it is zero to make the voltage that this submodule is inserted into circuit；It is inserted into shape
State refers to through on-off action, and the voltage that this submodule is inserted into circuit is made to be equal to submodule DC capacitor vc；Lock-out state is
Referring to submodule, switch clicks and enters the electricity that the voltage in circuit is depended in short circuit all in off-state, at this time submodule above and below
Whether stream direction can pass freely through diode D1、D2, voltage is inserted into either 0 can also be vcap, such state in MMC just
It in often running and is of little use, only can just enable lock-out state under startup or certain emergencies.
It is averaged bridge arm model according to MMC, coordinates corresponding control algolithm that can build complete MMC systems based on it.If
Output voltage v is calculated by corresponding control algolithms *, circulation control voltage vc *Reference value and measure DC bus-bar voltage,
It just can obtain the insertion coefficient of the upper and lower bridge arms of MMC, you can MMC is controlled.Wherein output voltage reference value vs *It is by defeated
Go out current controller to be calculated, circulation voltage reference value vc *It is to be calculated by circulation controller.Fig. 4 is MMC overall controls
Block diagram：
When the failure of MMC-HVDC systems exchange side causes ac grid voltage that non-equilibrium state is presented, MMC circulation
Controller can be generated to inhibit positive and negative, the zero-sequence current that are generated in circulation under unbalanced power supply state to dc bus electricity
Pressure causes the zero sequence circulation of fluctuation.
Present invention improves over zero sequence circulation controller, this zero sequence controller passes through PR using DC bus-bar voltage as feedback quantity
Controller filters out the zero sequence circulation of two times of fundamental frequencies, and the output of circulation controller passes through as the additional 0 axis input under dq0 axis
The coordinate transform of dq0 to abc axis allows the output of circulation controller as circulation voltage reference value vc *, controlled with reference to traditional circulation
Method, Fig. 4 are novel zero sequence circulation controller block diagram.
The present invention improves traditional circular current control method, is added to 0 additional axis input control algorithm, realizes
The effect of DC bus-bar voltage Ripple Suppression in unbalanced power supply.
Since MMC systems unlike traditional 2/3 level current transformer has dc-link capacitance prevent voltage fluctuation, so MMC
DC bus-bar voltage be easier fluctuate, existing optimization method can not completely eliminate the ripple of DC bus-bar voltage, using new
Type zero sequence control algolithm under the premise of hardware cost is not increased, realizes effectively DC bus-bar voltage Ripple Suppression.
The foregoing is merely the preferred embodiment of the present invention, are not intended to limit the scope of the invention, every utilization
Equivalent structure or the flow transformation that description of the invention and accompanying drawing content are made, are directly or indirectly used in other relevant
Technical field is included within the scope of the present invention.
Claims (3)
1. one kind is based on modular multi-level converter imbalance fault optimization method, which is characterized in that the method is based on MMC
Circuit topological structure realizes that the MMC circuit topological structures include：Several phases, per mutually being connected by upper and lower bridge arm with inductance shape
Into, per mutually and on busbar, be composed in series per the upper and lower bridge arm of phase by equal number of N number of submodule, the method includes with
Lower step：
It output current, the reference value of circulation is calculated by corresponding control algolithm and measures direct current according to the MMC bridge arm models that are averaged
Busbar voltage；
According to the output current reference value, output current controller is input to, generates output voltage reference value；
According to the loop current reference value, it is inputted novel with zero sequence control function circulation controller, generation circulation electricity
Press reference value；
According to the output voltage reference value, circulation voltage reference value and DC bus-bar voltage obtain inserting for the upper and lower bridge arms of MMC
Enter coefficient, be input to MMC and complete control.
2. according to the method described in claim 1, it is characterized in that, output voltage reference value is calculated by output current controller
It obtains, circulation voltage reference value is calculated by circulation controller.
3. according to the method described in claim 2, it is characterized in that, the circulation controller is novel zero sequence circulation controller.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
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| CN201711351672.7A CN108258928A (en) | 2017-12-15 | 2017-12-15 | Based on modular multi-level converter imbalance fault optimization method |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201711351672.7A CN108258928A (en) | 2017-12-15 | 2017-12-15 | Based on modular multi-level converter imbalance fault optimization method |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112134475A (en) * | 2020-09-27 | 2020-12-25 | 重庆大学 | Modularized multi-level rectifier without bus voltage sensor and controllable rectification method thereof |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103560746A (en) * | 2013-11-21 | 2014-02-05 | 东南大学 | Multi-parallel inverter motor speed regulating system and control method thereof |
| CN104811067A (en) * | 2015-04-30 | 2015-07-29 | 山东大学 | PR (proportional resonant) controller-based NMC-HVDC (modular multilevel converter-high voltage direct current) circulating current suppression method |
-
2017
- 2017-12-15 CN CN201711351672.7A patent/CN108258928A/en active Pending
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103560746A (en) * | 2013-11-21 | 2014-02-05 | 东南大学 | Multi-parallel inverter motor speed regulating system and control method thereof |
| CN104811067A (en) * | 2015-04-30 | 2015-07-29 | 山东大学 | PR (proportional resonant) controller-based NMC-HVDC (modular multilevel converter-high voltage direct current) circulating current suppression method |
Non-Patent Citations (2)
| Title |
|---|
| JINYU WANG ET AL.,: ""Circulating Current Suppression for MMC-HVDC under Unbalanced Grid Conditions"", 《IEEE TRANSACTTONS ON TNOLJSTRY APPLICATTONS》 * |
| JI-WOO MOON ET AL.,: ""Circulating Current Control in MMC Under the Unbalanced Voltage"", 《IEEE TRANSACTIONS ON POWER DELIVERY》 * |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112134475A (en) * | 2020-09-27 | 2020-12-25 | 重庆大学 | Modularized multi-level rectifier without bus voltage sensor and controllable rectification method thereof |
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Application publication date: 20180706 |