CN102983584B - A kind of THE UPFC for unbalanced system - Google Patents

A kind of THE UPFC for unbalanced system Download PDF

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Publication number
CN102983584B
CN102983584B CN201210267168.XA CN201210267168A CN102983584B CN 102983584 B CN102983584 B CN 102983584B CN 201210267168 A CN201210267168 A CN 201210267168A CN 102983584 B CN102983584 B CN 102983584B
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China
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brachium pontis
converter
series
upfc
split capacitor
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CN102983584A (en
Inventor
王轩
喻劲松
闫殳裔
李欣
武守远
何维国
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State Grid Corp of China SGCC
Shanghai Municipal Electric Power Co
China EPRI Science and Technology Co Ltd
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State Grid Corp of China SGCC
Shanghai Municipal Electric Power Co
China EPRI Science and Technology Co Ltd
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    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E40/00Technologies for an efficient electrical power generation, transmission or distribution
    • Y02E40/10Flexible AC transmission systems [FACTS]
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E40/00Technologies for an efficient electrical power generation, transmission or distribution
    • Y02E40/40Arrangements for reducing harmonics
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E40/00Technologies for an efficient electrical power generation, transmission or distribution
    • Y02E40/50Arrangements for eliminating or reducing asymmetry in polyphase networks

Abstract

The present invention relates to a kind of THE UPFC for unbalanced system.THE UPFC comprises STATCOM and Static Series Synchronous Compensator; Top split capacitor and bottom split capacitor is provided with between STATCOM and Static Series Synchronous Compensator; It is in parallel with STATCOM and Static Series Synchronous Compensator respectively after top split capacitor and bottom divide capacitances in series; Split capacitor branch road is formed after top split capacitor and bottom division capacitances in series; The mid point of split capacitor branch road is connected with the neutral point of the series transformer of described Static Series Synchronous Compensator; The output of STATCOM is connected with electrical network respectively with the output of described Static Series Synchronous Compensator.This THE UPFC is convenient to individual-phase control and modularized design, and THE UPFC UPFC running wastage is little, and voltage control capability is good, and zero-sequence current is controlled well, and number of elements is few, and cost is low, and cost performance is high.

Description

A kind of THE UPFC for unbalanced system
Technical field
The present invention relates to a kind of THE UPFC of Survey of Flexible AC Transmission System field, be specifically related to a kind of THE UPFC for unbalanced system.
Background technology
110kV and above neutral point of electric network adopt direct grounding way, when threephase load is asymmetric, circuit there will be zero-sequence current.Non-equilibrium among three phase voltages is the important indicator weighing the electrical network quality of power supply.Along with the raising that people require the quality of power supply, voltage imbalance question is just receiving increasing concern.In three-phase system, cause the reason of Voltage unbalance mainly from two aspects: the output voltage of generator is uneven and load is asymmetric.Theoretically, the output voltage of generator is not full symmetric, has certain degree of unbalance, but in the scope that allows of the standard that all should be limited in.The impossible full symmetric of threephase load of distribution end, particularly in the occasion that large capacity single phase load exists, voltage imbalance question is particularly serious.When Voltage unbalance is comparatively serious, the normal work of some equipment will be affected, as motor, power electronic equipment etc.Electric locomotive is the high-power single-phase rectification load that fluctuation is very large, for the power system power supply of three-phase symmetrical, electricity railway traction load has the feature of non-linear, asymmetric and fluctuation, by producing the harmonic current injection system of three-phase imbalance, makes the voltage fluctuation of electric power system.Therefore, at electric locomotive high speed development, under the background increasing to electric network influencing, the control for unbalanced system seems particularly important.
THE UPFC (UPFC) is flexible AC transmission of new generation (FACTS) device that a kind of function is the most powerful, characteristic is superior, it is the FACTS device that versatility is best up to now, combine the multiple flexible control device of FACTS element, by means of only the change of control law, just several different functions such as shunt compensation, series compensation and phase shift can be realized respectively or simultaneously.UPFC device can be regarded as STATCOM (STATCOM) device and Static Series Synchronous Compensator (SSSC) device is formed at DC side parallel, it can simultaneously and fast, independently control active power in transmission line and reactive power, thus the four quadrant running function making UPFC have STATCOM, SSSC device not possess.
UPFC device main circuit topology adopts the mode of two voltage source converter (VSC) DC side parallels, and wherein an AC side of converter is direct or in parallel with system by transformer, and another AC side of converter is by transformer and Cascade System.Each voltage source converter adopts two level or three-level three-phase voltage source converter structure usually.
In Large Copacity UPFC, voltage source converter usually adopts and can turn off the voltage endurance capability that mode that power electronic device (typical device is as insulated gate bipolar transistor IGBT) connects improves device.The technological difficulties that turn-off device IGBT connects are mainly manifested in: by the impact of technical monopoly, and the IGBT device with self limiting short-circuit current characteristic is difficult to buying, and it is not deep enough that the control technology of IGBT series average-voltage is studied in theory.For reducing device output harmonic wave, need to adopt higher switching frequency, thus plant running loss is larger.These limit the application of Large Copacity UPFC.
Summary of the invention
For the deficiencies in the prior art, the invention provides a kind of THE UPFC UPFC main circuit topological structure, modularization multi-level converter is adopted to form current transformer, avoid the technological difficulties of devices in series, this THE UPFC has following characteristics: be convenient to individual-phase control and modularized design, can bypass trouble unit by redundant technique, and then improves THE UPFC operational reliability, devices switch frequency is low, and THE UPFC UPFC running wastage is little.DC bus adopts two capacitors to divide mid-point voltage, and is connected with output transformer neutral point, forms three-phase and four-line MMC converter, has the following advantages: voltage control capability is good, and zero-sequence current is controlled well, and number of elements is few, and cost is low, and cost performance is high.
The object of the invention is to adopt following technical proposals to realize:
For a THE UPFC for unbalanced system, its improvements are, described THE UPFC comprises STATCOM 1 and Static Series Synchronous Compensator 2;
Top split capacitor 3 and bottom split capacitor 4 is provided with between described STATCOM 1 and Static Series Synchronous Compensator 2; Described top split capacitor 3 and bottom split capacitor 4 are in parallel with STATCOM 1 and Static Series Synchronous Compensator 2 respectively after connecting;
Described top split capacitor 3 and bottom split capacitor 4 form split capacitor branch road after connecting; The mid point of described split capacitor branch road is connected with the neutral point of the series transformer 11 of described Static Series Synchronous Compensator 2;
The output of described STATCOM 1 is connected with electrical network respectively with the output of described Static Series Synchronous Compensator 2.
Wherein, described STATCOM 1 comprises start-up circuit 6, converter 8 and access transformer 9;
Described converter 8 one end is connected with electrical network with access transformer 9 by described start-up circuit 6 successively;
The secondary of described access transformer 9 is connected with described start-up circuit 6; The former limit of described access transformer 9 is connected with described electrical network.
Wherein, described converter 8 is made up of three-phase; Parallel three phase; Two brachium pontis up and down that every structure by connecting is identical are formed; The midpoint of upper and lower two brachium pontis draws the output as described STATCOM 1.
Wherein, in described upper and lower two brachium pontis, each brachium pontis comprises 1 reactor submodule identical with N number of structure; After the sub module cascade of each brachium pontis, one end is connected with described start-up circuit 6 by reactor; After the sub module cascade of each brachium pontis, the other end is connected with submodule one end of the cascade of another two-phase brachium pontis, forms the both positive and negative polarity bus of described converter 8; Or
In described upper and lower two brachium pontis, each brachium pontis comprises 1 reactor submodule identical with N number of structure; After the sub module cascade of each brachium pontis, one end is connected with described start-up circuit 6; Be connected with the reactor of another two-phase brachium pontis after other end series reactor after the sub module cascade of each brachium pontis, form the both positive and negative polarity bus of described converter 8.
Wherein, described start-up circuit 6 comprises resistance in parallel and switch.
Wherein, described Static Series Synchronous Compensator 2 comprises start-up circuit 7, converter 10 and series transformer 11;
Described converter 10 one end is connected with electrical network with series transformer 11 by start-up circuit 7 successively.
Described converter 10 other end is connected with the other end of converter 8 by split capacitor branch road.
Wherein, described converter 10 is made up of three-phase; Parallel three phase; Two brachium pontis up and down that every structure by connecting is identical are formed; The midpoint of upper and lower two brachium pontis draws the output as described Static Series Synchronous Compensator 2.
Wherein, in described upper and lower two brachium pontis, each brachium pontis comprises 1 reactor submodule identical with M structure; After the sub module cascade of each brachium pontis, one end is connected with described series transformer 11 by reactor; The other end is connected with submodule one end of the cascade of another two-phase brachium pontis, forms described converter 10 both positive and negative polarity bus, correspondingly with the both positive and negative polarity bus of described converter 8 respectively connects; Or
In described upper and lower two brachium pontis, each brachium pontis comprises 1 reactor submodule identical with M structure; After the sub module cascade of each brachium pontis, one end is connected with described series transformer 11 by reactor; Be connected with the reactor of another two-phase brachium pontis after other end series reactor, form the both positive and negative polarity bus of described converter 10, correspondingly with the both positive and negative polarity bus of described converter 8 respectively to connect.
Wherein, described start-up circuit 7 comprises resistance in parallel and switch.
Wherein, described THE UPFC comprises by-pass switch 5; Described by-pass switch 5 is in parallel with described series transformer 11.
Wherein, the former limit of described series transformer 11 is connected with electrical network and start-up circuit 7 respectively; Described series transformer 11 secondary is connected with load.
Wherein, described submodule is formed by half-bridge structure is in parallel with DC capacitor, and described half-bridge structure comprises the IGBT module of two series connection, and each IGBT module comprises antiparallel IGBT and diode;
Described half-bridge structure mid point submodule bypass circuit in parallel with between IGBT emitter;
The control circuit that described DC capacitor is submodule by draw-out power supply provides power supply.
Wherein, the both positive and negative polarity bus of described converter 8 and converter 10 both positive and negative polarity bus are called DC bus; Described DC bus adopts top split capacitor 3 and bottom split capacitor 4 to divide mid-point voltage, and is connected with the neutral point of series transformer 11, forms three-phase and four-line modularization multi-level converter MMC.
Compared with the prior art, the beneficial effect that the present invention reaches is:
1, the THE UPFC for unbalanced system provided by the invention, can significantly improve THE UPFC capacity, without the need to adopting the technology of complicated IGBT device series connection;
2, the THE UPFC for unbalanced system provided by the invention can realize individual-phase control;
3, the THE UPFC for unbalanced system provided by the invention can realize modularized design;
4, the THE UPFC for unbalanced system provided by the invention can bypass trouble unit by redundant technique, improves plant running reliability;
5, the THE UPFC for unbalanced system provided by the invention, for reducing output harmonic wave, IGBT device tandem plan switching frequency is usually very high, and device loss is large; This programme have employed modular multilevel technology, and the switching frequency of each device is low, but it is very high to realize external equivalent switching frequency, and reduce output harmonic wave, therefore plant running loss is little;
6, the THE UPFC for unbalanced system provided by the invention, three-phase and four-line topological structure voltage control capability is good, and zero-sequence current is controlled well, and number of elements is few, and cost is low, and cost performance is high.
Accompanying drawing explanation
Fig. 1 is the single-phase MMC topology diagram of series side;
Fig. 2 is series side four bridge legs MMC topology diagram;
Fig. 3 is three-phase and four-line MMC topological project one schematic diagram of the THE UPFC series side band split capacitor for unbalanced system provided by the invention;
Wherein: (1) is STATCOM, (2) are Static Series Synchronous Compensator, (3) are top split capacitor, (4) are bottom split capacitor, (5) are by-pass switch, (6) are start-up circuit, (7) are start-up circuit, (8) are converter, (9) are access transformer, (10) are converter, (11) are series transformer.
Embodiment
Below in conjunction with accompanying drawing, the specific embodiment of the present invention is described in further detail.
The present invention proposes a kind of THE UPFC UPFC for unbalanced system, the technological difficulties of devices in series are evaded, have and be convenient to individual-phase control and modularized design, can bypass trouble unit by redundant technique, improve THE UPFC operational reliability, and devices switch frequency is low, THE UPFC running wastage is little.
Series side MMC converter can adopt following several scheme:
The single-phase MMC scheme of I, series side (accompanying drawing 1).Series side often adopts full bridge structure mutually, exports and seals in circuit by single-phase transformer.Program series side three-phase can independent regulation, controls flexibly, superior performance, and control strategy is relatively simple.But program number of elements is maximum, and cost is the highest, and cost performance is low.
II, series side four bridge legs MMC scheme (accompanying drawing 2).Series side is made up of four MMC brachium pontis, exports and seals in circuit by single-phase or three-phase (five posts) transformer.Program series side three-phase voltage is not so good as single-phase invertor and controls like that flexibly, and number of elements is many, and cost is high, and cost performance is lower.
The three-phase and four-line MMC scheme (accompanying drawing 3) of III, series side band split capacitor.DC bus adopts two capacitors to divide mid-point voltage, and is connected with output transformer neutral point, forms three-phase and four-line MMC converter, have following characteristics: voltage control capability is better, zero-sequence current controls better, and number of elements is less, cost is lower, and cost performance is higher.
The present invention adopts the three-phase and four-line MMC scheme of series side band split capacitor.
Embodiment 1
As shown in Figure 3, THE UPFC comprises STATCOM 1 and Static Series Synchronous Compensator 2 to the three-phase and four-line MMC topological project one of a kind of THE UPFC series side band split capacitor for unbalanced system provided by the invention; Top split capacitor 3 and bottom split capacitor 4 is provided with between STATCOM 1 and Static Series Synchronous Compensator 2; Top split capacitor 3 and bottom split capacitor 4 are in parallel with STATCOM 1 and Static Series Synchronous Compensator 2 respectively after connecting; Top split capacitor 3 and bottom split capacitor 4 form split capacitor branch road after connecting; The mid point of split capacitor branch road is connected with the neutral point of the series transformer 11 of described Static Series Synchronous Compensator 2; The output of STATCOM 1 is connected with electrical network respectively with the output of described Static Series Synchronous Compensator 2.
Both positive and negative polarity bus and the Static Series Synchronous Compensator 2 both positive and negative polarity bus of STATCOM 1 are called DC bus; DC bus adopts two capacitors 3 and 4 to divide mid-point voltage, and is connected with series transformer 11 neutral point, forms three-phase and four-line MMC converter.Neutral point current can flow through two split capacitor 3 and 4.
STATCOM 1 is connected by the intermediate DC link be made up of with 4 split capacitor 3 with Static Series Synchronous Compensator 2, and such active power can carry out bi-directional between two current converters; Reactive power can be exchanged with system at its AC independently by each current converter.
STATCOM 1 comprises start-up circuit 6, converter 8 and access transformer 9; Converter 8 one end is connected with electrical network with access transformer 9 by start-up circuit 6 successively; The secondary of access transformer 9 is connected with start-up circuit 6; The former limit of access transformer 9 is connected with electrical network.
Converter 8 is made up of three-phase; Parallel three phase; Two brachium pontis up and down that every structure by connecting is identical are formed; The midpoint of upper and lower two brachium pontis draws the output as STATCOM 1.
Wherein, in upper and lower two brachium pontis, each brachium pontis comprises 1 reactor with N(N is natural number) submodule that individual structure is identical; After the sub module cascade of each brachium pontis, one end is connected with start-up circuit 6 by reactor; After the sub module cascade of each brachium pontis, the other end is connected with submodule one end of the cascade of another two-phase brachium pontis, forms the both positive and negative polarity bus of converter 8; Concrete, half-bridge brachium pontis mid point and lower pipe IGBT emitter, respectively as submodule exit, are connected with the submodule of front and back successively, then with 1 change of current reactance 1 brachium pontis in series.Upper and lower two brachium pontis series connection, forms 1 phase current converter, and three-phase current converter is overall in parallel, and draws positive and negative busbar.Upper and lower bridge arm midpoint draws the output as STATCOM converter, after connecting with start-up circuit 6, by transformer 9 connecting system in parallel with system.Access transformer 9 is for realizing mating of system voltage and STATCOM device output voltage.
Start-up circuit 6 is formed by starting resistance is in parallel with starting resistance by-pass switch.Start-up circuit 6 is for realizing the soft start of STATCOM 1.
Converter 10 is identical with converter 8 structure, and converter 10 is made up of three-phase; Parallel three phase; Two brachium pontis up and down that every structure by connecting is identical are formed; The midpoint of upper and lower two brachium pontis draws the output as described Static Series Synchronous Compensator 2.
In upper and lower two brachium pontis, each brachium pontis comprises 1 reactor and M(M is natural number, and M can equal N, also can be not equal to N) submodule that individual structure is identical; After the sub module cascade of each brachium pontis, one end is connected with described series transformer 11 by reactor; The other end is connected with submodule one end of the cascade of another two-phase brachium pontis, forms described converter 10 both positive and negative polarity bus, correspondingly with the both positive and negative polarity bus of described converter 8 respectively connects.
Concrete, half-bridge brachium pontis mid point and lower pipe IGBT emitter, respectively as submodule exit, are connected with the submodule of front and back successively, then with 1 change of current reactance 1 brachium pontis in series.Upper and lower two brachium pontis series connection, forms 1 phase current converter, and three-phase current converter is overall in parallel, and draws positive and negative busbar.Upper and lower bridge arm midpoint draws the output as SSSC converter, after connecting with start-up circuit 7, by transformer 11 connecting system with Cascade System.The submodule of the present embodiment is connected with system by reactor, can to suppress on the one hand from the thunder and lightning of electrical network, operation ripple, to the infringement of equipment, can suppress current converter output harmonic wave on the other hand.
Series transformer 11 neutral point with connected by top split capacitor 3 and bottom split capacitor 4 after divide the mid point and be connected.One end, former limit of series transformer 11 is connected with system, and one end is connected with load.Series transformer 11 is for realizing mating of system voltage and Static Series Synchronous Compensator 2 output voltage.
Start-up circuit 7 is formed by starting resistance is in parallel with starting resistance by-pass switch.Start-up circuit 7 is for realizing the soft start of Static Series Synchronous Compensator 2.
Preferably, the THE UPFC of the present embodiment, in order to security setting, is also provided with by-pass switch 5, and by-pass switch 5 is in parallel with series transformer 11, for realizing exiting of Static Series Synchronous Compensator.
The submodule of the present embodiment is for exporting required voltage, it is made up of half-bridge structure and DC capacitor, described half-bridge structure comprises the IGBT module of upper and lower two series connection, parallel connection direct electric capacity between upper pipe IGBT collector electrode and lower pipe IGBT emitter, submodule bypass circuit in parallel between half-bridge structure mid point with lower pipe IGBT emitter, draw-out power supply is from direct current capacitor power taking, and the control circuit for submodule provides control power supply.The DC capacitor of submodule is used for providing submodule voltage support.During submodule internal fault, its bypass circuit is used for making submodule out of service, realizes the redundancy running of STATCOM.Draw-out power supply is used for providing control power supply to submodule control circuit.Control circuit is for realizing control to submodule, monitoring and protection.The bypass circuit of the present embodiment can be realized by switch, and control circuit can be realized by numeral or analog circuit.Draw-out power supply can referenced patent 201010624225.6 or ZL201020700480.X realization.
Embodiment 2
The present embodiment is substantially the same manner as Example 1, but distinctive points is:
Converter 8 is different with the position of the reactor in converter 10.The reactor string of the present embodiment is in positive and negative busbar side, and it is for suppressing current converter output harmonic wave.
Concrete, converter 8 is made up of three-phase; Parallel three phase; Two brachium pontis up and down that every structure by connecting is identical are formed; The midpoint of upper and lower two brachium pontis draws the output as STATCOM 1.In upper and lower two brachium pontis, each brachium pontis comprises 1 reactor submodule identical with N number of structure; After the sub module cascade of each brachium pontis, one end is connected with start-up circuit 6; Be connected with the reactor of another two-phase brachium pontis after other end series reactor after the sub module cascade of each brachium pontis, form the both positive and negative polarity bus of described converter 8.
Converter 10 is made up of three-phase; Parallel three phase; Two brachium pontis up and down that every structure by connecting is identical are formed; The midpoint of upper and lower two brachium pontis draws the output as described Static Series Synchronous Compensator 2.In upper and lower two brachium pontis, each brachium pontis comprises 1 reactor submodule identical with M structure; After the sub module cascade of each brachium pontis, one end is connected with described series transformer 11 by reactor; Be connected with the reactor of another two-phase brachium pontis after other end series reactor, form the both positive and negative polarity bus of described converter 10, correspondingly with the both positive and negative polarity bus of described converter 8 respectively to connect.
THE UPFC UPFC for unbalanced system provided by the invention, wherein DC bus adopts two capacitors to divide mid-point voltage, and be connected with output transformer neutral point, form three-phase and four-line MMC converter, there is following characteristics: voltage control capability is good, and zero-sequence current is controlled well, and number of elements is few, cost is low, and cost performance is high.
Finally should be noted that: above embodiment is only in order to illustrate that technical scheme of the present invention is not intended to limit, although with reference to above-described embodiment to invention has been detailed description, those of ordinary skill in the field are to be understood that: still can modify to the specific embodiment of the present invention or equivalent replacement, and not departing from any amendment of spirit and scope of the invention or equivalent replacement, it all should be encompassed in the middle of right of the present invention.

Claims (4)

1. for a THE UPFC for unbalanced system, it is characterized in that, described THE UPFC comprises STATCOM (1) and Static Series Synchronous Compensator (2);
Top split capacitor (3) and bottom split capacitor (4) is provided with between described STATCOM (1) and Static Series Synchronous Compensator (2); Described top split capacitor (3) and bottom split capacitor (4) are in parallel with STATCOM (1) and Static Series Synchronous Compensator (2) respectively after connecting;
Split capacitor branch road is formed after described top split capacitor (3) and bottom split capacitor (4) series connection; The mid point of described split capacitor branch road is connected with the neutral point of the series transformer (11) of described Static Series Synchronous Compensator (2);
Described THE UPFC comprises by-pass switch (5); Described by-pass switch (5) is in parallel with described series transformer (11);
The output of described STATCOM (1) is connected with electrical network respectively with the output of described Static Series Synchronous Compensator (2);
Described STATCOM (1) comprises the first start-up circuit (6), the first converter (8) and access transformer (9);
Described first converter (8) one end is connected with electrical network with access transformer (9) by described first start-up circuit (6) successively;
The secondary of described access transformer (9) is connected with described first start-up circuit (6); The former limit of described access transformer (9) is connected with described electrical network;
Described first converter (8) is made up of three-phase; Parallel three phase; Two brachium pontis up and down that every structure by connecting is identical are formed; The midpoint of upper and lower two brachium pontis draws the output as described first converter (8);
In described upper and lower two brachium pontis, each brachium pontis comprises 1 reactor submodule identical with N number of structure; After the sub module cascade of each brachium pontis, one end is connected with described first start-up circuit (6) by reactor; After the sub module cascade of each brachium pontis, the other end is connected with submodule one end of the cascade of another two-phase brachium pontis, forms the both positive and negative polarity bus of described first converter (8); Or
In described upper and lower two brachium pontis, each brachium pontis comprises 1 reactor submodule identical with N number of structure; After the sub module cascade of each brachium pontis, one end is connected with described first start-up circuit (6); Be connected with the reactor of another two-phase brachium pontis after other end series reactor after the sub module cascade of each brachium pontis, form the both positive and negative polarity bus of described first converter (8);
Described Static Series Synchronous Compensator (2) comprises the second start-up circuit (7), the second converter (10) and series transformer (11);
Described second converter (10) one end is connected with electrical network with series transformer (11) by the second start-up circuit (7) successively;
Described second converter (10) other end is connected with the other end of the first converter (8) by split capacitor branch road;
Described second converter (10) is made up of three-phase; Parallel three phase; Two brachium pontis up and down that every structure by connecting is identical are formed; The midpoint of upper and lower two brachium pontis draws the output as described second converter (10);
In described upper and lower two brachium pontis, each brachium pontis comprises 1 reactor submodule identical with M structure; After the sub module cascade of each brachium pontis, one end is connected with described series transformer (11) by reactor; The other end is connected with submodule one end of the cascade of another two-phase brachium pontis, forms described second converter (10) both positive and negative polarity bus, correspondingly with the both positive and negative polarity bus of described first converter (8) respectively connects; Or
In described upper and lower two brachium pontis, each brachium pontis comprises 1 reactor submodule identical with M structure; After the sub module cascade of each brachium pontis, one end is connected with described series transformer (11) by reactor; Be connected with the reactor of another two-phase brachium pontis after other end series reactor, form described second converter (10) both positive and negative polarity bus, correspondingly with the both positive and negative polarity bus of described first converter (8) respectively to connect;
The former limit of described series transformer (11) is connected with electrical network and the second start-up circuit (7) respectively; Described series transformer (11) secondary is connected with load;
Both positive and negative polarity bus and the second converter (10) the both positive and negative polarity bus of described first converter (8) are called DC bus; Described DC bus adopts top split capacitor (3) and bottom split capacitor (4) to divide mid-point voltage, and is connected with the neutral point of series transformer (11), forms three-phase and four-line modularization multi-level converter MMC.
2. THE UPFC as claimed in claim 1, is characterized in that, described first start-up circuit (6) comprises resistance in parallel and switch.
3. THE UPFC as claimed in claim 2, is characterized in that, described second start-up circuit (7) comprises resistance in parallel and switch.
4. THE UPFC as claimed in claim 1, it is characterized in that, described submodule is formed by half-bridge structure is in parallel with DC capacitor, and described half-bridge structure comprises the IGBT module of two series connection, and each IGBT module comprises antiparallel IGBT and diode;
Described half-bridge structure mid point submodule bypass circuit in parallel with between IGBT emitter;
The control circuit that described DC capacitor is submodule by draw-out power supply provides power supply.
CN201210267168.XA 2012-07-13 2012-07-13 A kind of THE UPFC for unbalanced system Active CN102983584B (en)

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CN102983584B true CN102983584B (en) 2015-08-05

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CN103311944B (en) * 2013-05-16 2016-04-20 国家电网公司 A kind of THE UPFC and starting method thereof adopting modular construction
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