CN114784779A - Multifunctional arc suppression converter and control method thereof - Google Patents

Multifunctional arc suppression converter and control method thereof Download PDF

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Publication number
CN114784779A
CN114784779A CN202210571213.4A CN202210571213A CN114784779A CN 114784779 A CN114784779 A CN 114784779A CN 202210571213 A CN202210571213 A CN 202210571213A CN 114784779 A CN114784779 A CN 114784779A
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circuit unit
phase
square wave
voltage
converter
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侯玉超
郭祺
涂春鸣
王鑫
黄泽钧
任鹏
肖凡
葛平娟
李庆
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Hunan University
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Hunan University
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H9/00—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection
    • H02H9/08—Limitation or suppression of earth fault currents, e.g. Petersen coil
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/18—Arrangements for adjusting, eliminating or compensating reactive power in networks
    • H02J3/1821—Arrangements for adjusting, eliminating or compensating reactive power in networks using shunt compensators
    • 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
    • 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
    • H02M7/487—Neutral point clamped inverters

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Abstract

The multifunctional arc suppression converter comprises three-phase cascaded H-bridge shaping circuit units, wherein each phase of the cascaded H-bridge shaping circuit units has the same structure and comprises a plurality of sub-modules, the multifunctional arc suppression converter further comprises a square wave circuit unit which is connected with the cascaded H-bridge shaping circuit units in series, and the square wave circuit unit is a three-phase four-leg diode clamping type circuit. When the power distribution network is normal, the n phases of the NPC converters in the square wave circuit units are blocked, the multifunctional arc suppression converter works in a reactive compensation mode, when the power distribution network has a single-phase earth fault, the multifunctional arc suppression converter works in an arc suppression mode, arc suppression current is injected by one phase or two phases of a non-fault phase to compensate the ground capacitance current of the power distribution network, and therefore the current of a fault point is suppressed to be 0. The multifunctional arc suppression converter provided by the invention can effectively reduce the number of cascades, reduce the cost, reduce the loss and improve the efficiency and the power density.

Description

Multifunctional arc suppression converter and control method thereof
Technical Field
The invention relates to the technical field of arc extinction of power distribution networks, in particular to a multifunctional arc extinction converter and a control method thereof.
Background
The structure of the power distribution network is complex and changeable, random faults occur frequently, and more than 70% of the faults are single-phase earth faults. And with the continuous increase of distribution network capacity and the continuous increase of cable line ratio, single-phase earth fault current sharply increases, and electric arc is difficult to extinguish by oneself. If the electric arc cannot be extinguished in time, serious electric power accidents such as insulation breakdown, interphase short circuit, forest fire and the like are easily caused.
The arc suppression coil is widely applied to a power distribution network as a typical passive arc suppression device, but the arc suppression coil can only compensate reactive components in grounding current, cannot compensate active and harmonic components, and is difficult to ensure reliable arc suppression. The active arc suppression device based on the power electronic device can realize active, reactive and harmonic full compensation and becomes a research hotspot of the current arc suppression device. The active arc suppression device can be divided into a neutral point active arc suppression device and a non-neutral point active arc suppression device according to different positions of the power distribution network.
As shown in fig. 1, an active converter is connected in parallel with an arc suppression coil through a step-up transformer to a neutral point of a Z-type transformer, and is connected to a distribution network bus through the Z-type transformer. When the power distribution network has ground fault, the active converter and the arc suppression coil inject arc suppression current to the neutral point to suppress the reignition of the ground point arc. The active device of the arc extinction mode has small capacity and low cost, but the arc extinction coil and the transformer have large volumes, single function of equipment and low utilization rate. In addition, during the arc extinction period, in order to maintain the voltage on the DC side of the device constant, a rectifying device is additionally added.
A typical non-neutral point active arc suppression device is shown in figure 2, and adopts a cascade H-bridge star-shaped connection structure, star contacts of the cascade H-bridge star-shaped connection structure are directly connected with the ground, and an alternating current output side is connected to a power distribution network bus in a hanging mode through a filter inductor. When the power distribution network is normal, the device can realize functions of reactive power compensation, three-phase imbalance inhibition and the like; when the single-phase earth fault of the power distribution network occurs, the cascaded H-bridge converter injects arc suppression current into the power distribution network so as to suppress earth point arc reignition. Because the cascaded H bridge bears the line voltage during arc extinction, the active device has the problems of large number of cascaded devices, high cost, large loss, low power density and the like, so that the active device cannot be popularized and applied in a power distribution network. Therefore, if a multifunctional active arc-extinguishing device with higher efficiency and power density and better cost can be provided, the device has important significance for improving the performance and the application and popularization of the active arc-extinguishing device.
Disclosure of Invention
Aiming at the problems of the existing active arc suppression device, the invention provides a multifunctional arc suppression converter which can reduce the number of cascades, improve the efficiency and the power density and reduce the cost and a control method thereof.
In order to solve the technical problems, the invention adopts the following technical method: the multifunctional arc suppression converter further comprises a square wave circuit unit which is connected with the cascaded H bridge shaping circuit unit in series, and the square wave circuit unit is a diode clamping type circuit with three phases and four bridge arms.
Furthermore, the square wave circuit unit comprises a three-phase four-leg NPC converter and two energy storage capacitors CT1、CT2The NPC converter comprises a phase a, a phase b, a phase c and a phase n, each phase comprises four IGCTs and two clamping diodes, and the cathode of one IGCT above the four IGCTs is connected with the cathode of the next IGCTThe anodes of the IGCTs are electrically connected in series in sequence, the cathode of the first clamping diode is electrically connected to the cathode of the first IGCT, the anode of the first clamping diode is connected to the cathode of the second clamping diode, and the anode of the second clamping diode is electrically connected to the cathode of the third IGCT; the energy storage capacitor CT1、CT2An energy storage capacitor C arranged on the DC side of the NPC converterT1The anode of the NPC converter is electrically connected with the anode of the first IGCT of each phase, and the energy storage capacitor CT1The negative pole of the NPC converter is electrically connected with the positive pole of the first clamping diode of each phase, and the energy storage capacitor CT2Positive electrode and energy storage capacitor CT1Is electrically connected to the point O and an energy storage capacitor CT2The negative electrode of the NPC converter is electrically connected with the cathode of the fourth IGCT of each phase of the NPC converter; the alternating current output ports of the a phase, the b phase and the c phase of the NPC converter are respectively led out from the positions between the second IGCT and the third IGCT of the corresponding phases of the NPC converter and are electrically connected with the submodules of the corresponding phases in the cascade H-bridge shaping circuit unit, and the positions between the second IGCT and the third IGCT of the n phase of the NPC converter are grounded.
Still further, the number of each phase of sub-modules of the cascaded H-bridge shaping circuit unit is n, and the sub-modules comprise T11、T12、T21、T22Single-phase full-bridge converter formed by four IGBTs and energy storage capacitor C installed on direct current side of single-phase full-bridge converterH(ii) a In each submodule, a single-phase full-bridge converter T11Emitter and T12Are electrically connected together as output port, T21Emitter and T22Are electrically connected together as an input port, an energy storage capacitor CHPositive electrode of (2) and T11、T21Is electrically connected with the collector of the energy storage capacitor CHNegative electrode and T12、T22Is electrically connected with the emitter; in the cascaded H-bridge shaping circuit unit, the n submodules of each phase are sequentially connected in series in a way that the input ports of more than one submodule are electrically connected to the output port of the next submodule, the output port of the first submodule is connected in series with the filter inductor L and then is connected to a grid-connected point, and the input port of the last submodule is electrically connected to the square wave circuitAnd the alternating current output ports of the corresponding phases in the units.
As another aspect of the present invention, a method for controlling the multifunctional arc suppression converter includes: dividing the modulation of the multifunctional arc suppression converter into square wave circuit unit modulation and cascade H-bridge shaping circuit unit modulation, wherein the multifunctional arc suppression converter outputs voltage
Figure BDA0003659258780000031
For shaped voltage output by cascaded H-bridge shaping circuit units
Figure BDA0003659258780000032
Voltage output by square wave circuit unit
Figure BDA0003659258780000033
The sine wave formed by shaping has the following calculation formula:
Figure BDA0003659258780000034
when the power distribution network is normal, the n phase of the NPC converter in the square wave circuit unit is blocked, and the multifunctional arc suppression converter works in a reactive power compensation mode;
when a single-phase earth fault occurs in the power distribution network, the multifunctional arc suppression converter works in an arc suppression mode, and one phase or two phases of a non-fault phase are used for injecting arc suppression current to compensate capacitance current of the power distribution network to earth, so that the current of a fault point is suppressed to be 0.
Further, when the power distribution network is normal, the modulation process of the square wave circuit unit and the cascaded H-bridge shaping circuit unit is as follows:
1) square wave circuit unit
The square wave circuit unit adopts the nearest level approximation control, the n phase of the NPC converter is blocked, the a phase, the b phase and the c phase are matched, and the voltage output by the square wave circuit unit in a period
Figure BDA0003659258780000035
With Udc、0、-UdcThree levels;
setting the output reference voltage of the multifunctional arc suppression converter to
Figure BDA0003659258780000036
In that
Figure BDA0003659258780000037
In the positive half period of (1), when
Figure BDA0003659258780000038
Energy storage capacitor C larger than square wave circuit unit direct current sideT1Or CT2At a voltage of (2), i.e.
Figure BDA0003659258780000039
Voltage output by square wave circuit unit
Figure BDA00036592587800000310
Is a positive level voltage Udc(ii) a In that
Figure BDA00036592587800000311
In the negative half period of (c) when
Figure BDA00036592587800000312
Voltage outputted from square wave circuit unit
Figure BDA00036592587800000313
Is a negative level voltage-UdcIn other cases, the voltage output by the square wave circuit unit
Figure BDA00036592587800000314
Is 0;
2) cascaded H-bridge shaping circuit unit
The cascaded H-bridge shaping circuit unit adopts unipolar carrier phase shift control, and the output shaping reference voltage thereof
Figure BDA00036592587800000315
Output reference voltage of multifunctional arc suppression converter
Figure BDA00036592587800000316
And the voltage output by the square wave circuit unit
Figure BDA00036592587800000317
Calculated as follows:
Figure BDA00036592587800000318
Figure BDA0003659258780000041
the per unit value of the voltage is used as the modulation wave of each submodule, the triangular carrier phase of each submodule is sequentially different from pi/n, and the cascaded H-bridge shaping circuit unit outputs shaping voltage
Figure BDA0003659258780000042
Further, when a single-phase earth fault occurs in the power distribution network, the modulation processes of the square wave circuit unit and the cascaded H-bridge shaping circuit unit are as follows:
1) square wave circuit unit
The square wave circuit unit adopts the nearest level approximation control, n phases of the square wave circuit unit are matched with b and c, and the voltage output by the square wave circuit unit in one period
Figure BDA0003659258780000043
Has 2Udc、Udc、0、-Udc、-2UdcFive levels;
setting the output reference voltage of the multifunctional arc suppression converter to be
Figure BDA0003659258780000044
In that
Figure BDA0003659258780000045
In the positive half period of (2)
Figure BDA0003659258780000046
And square wave circuit unit direct current side energy storage capacitor CT1Or CT2At a voltage of
Figure BDA0003659258780000047
Voltage outputted from square wave circuit unit
Figure BDA0003659258780000048
Is a positive level voltage UdcWhen it comes to
Figure BDA0003659258780000049
Voltage outputted from square wave circuit unit
Figure BDA00036592587800000410
Is a positive level voltage 2Udc(ii) a In that
Figure BDA00036592587800000411
During the negative half period of (c), when
Figure BDA00036592587800000412
Voltage outputted from square wave circuit unit
Figure BDA00036592587800000413
Is a negative level voltage-UdcWhen is coming into contact with
Figure BDA00036592587800000414
Voltage outputted from square wave circuit unit
Figure BDA00036592587800000415
Is a positive level voltage-2Udc(ii) a In other cases, the voltage output by the square wave circuit unit
Figure BDA00036592587800000416
Is 0;
2) cascaded H-bridge shaping circuit unit
The cascaded H-bridge shaping circuit unit adopts unipolar carrier phase shift control, and the output shaping reference voltage thereof
Figure BDA00036592587800000417
Output reference voltage of multifunctional arc suppression converter
Figure BDA00036592587800000418
And the voltage output by the square wave circuit unit
Figure BDA00036592587800000419
Calculated as follows:
Figure BDA00036592587800000420
Figure BDA00036592587800000421
the per unit value of the output voltage is used as the modulation wave of each submodule, the phase difference of the triangular carrier wave of each submodule is pi/n in sequence, and the b phase and the c phase of the cascade H-bridge shaping circuit unit output shaping voltage
Figure BDA00036592587800000422
Compared with the traditional arc extinction device, the multifunctional arc extinction converter provided by the invention can realize a reactive compensation function and a flexible arc extinction function at the same time, and the utilization rate and the practicability of equipment are greatly improved. The invention mainly utilizes the structure of the three-phase four-bridge arm square wave circuit unit and the cascaded H-bridge shaping circuit unit to be connected in series, thereby reducing the number of cascaded modules of the CHB, reducing the number of power electronic devices and direct current capacitors, and improving the power density and the efficiency of the device. In addition, the square wave circuit unit in the mixed topology of the multifunctional arc-extinguishing current transformer selects an IGCT device with low switching frequency, high voltage withstanding grade and low cost, so that the overall cost of the device can be reduced. In summary, the present invention can effectively reduce the number of device cascades, reduce cost, reduce loss, and improve efficiency and power density.
Drawings
Fig. 1 is a schematic view of a topology of a conventional neutral point active arc suppression device;
fig. 2 is a schematic view of a topology of a conventional non-neutral point active arc suppression device;
FIG. 3 is a schematic diagram of a hybrid topology of a multifunctional arc suppression converter involved in the present invention;
FIG. 4 is a reactive current flow diagram during reactive compensation of the multifunctional arc suppression converter according to the present invention;
FIG. 5 is a diagram of arc suppression current flow during arc suppression of the multifunctional arc suppression converter according to the present invention;
FIG. 6 is a schematic diagram of a modulation scheme of a normal time square wave circuit unit of the power distribution network in the embodiment of the invention;
fig. 7 is a schematic diagram of modulation of a cascaded H-bridge shaping circuit unit when a power distribution network is normal in the embodiment of the present invention;
fig. 8 is a schematic diagram of MF-ASC modulation when the distribution network is normal in the embodiment of the present invention;
fig. 9 is a schematic diagram of a square wave circuit unit modulation in the case of a single-phase earth fault of a power distribution network according to an embodiment of the present invention;
fig. 10 is a schematic diagram of modulation of a unit of a cascaded H-bridge shaping circuit in a single-phase ground fault of a power distribution network in the embodiment of the present invention;
fig. 11 is an MF-ASC modulation schematic diagram when a single-phase ground fault occurs in the power distribution network in the embodiment of the present invention.
Detailed Description
In order to facilitate understanding of those skilled in the art, the present invention is further described below with reference to the following examples and the accompanying drawings, which are not intended to limit the present invention.
As shown in fig. 3, a topology structure of a Multi-Functional arc suppression converter (MF-ASC) provided in this embodiment includes a three-phase four-leg diode clamp (NPC) square wave circuit unit and a cascade H-bridge (CHB) shaping circuit unit. In the context of figure 3, it is shown,
Figure BDA0003659258780000051
is a three-phase power supply voltage,
Figure BDA0003659258780000052
in order to obtain the voltage of the grid-connected point,
Figure BDA0003659258780000053
neutral zero-sequence voltage; r is a radical of hydrogena＝rb＝rc＝r0For three-phase line to ground resistance Ca＝Cb＝Cc＝C0For three-phase line capacitance to ground, RfIs a ground fault resistor.
Figure BDA0003659258780000054
Shaping voltage output by the cascaded H-bridge shaping circuit unit;
Figure BDA0003659258780000055
the voltage output by the square wave circuit unit, namely the voltage for the point O; u shapecDC side energy storage capacitor C of sub module in cascade H-bridge shaping circuit unitHVoltage value of (U)dc1、Udc2Respectively a square wave circuit unit DC side energy storage capacitor CT1、CT2Voltage value of (U)dc1＝Udc2＝Udc。
Specifically, as shown in fig. 3, the square wave circuit unit of the multifunctional arc suppression converter provided by the present embodiment includes a three-phase four-leg NPC converter and two energy storage capacitors CT1、CT2The NPC converter has four phases (a phase, b phase, c phase and n phase), each phase has the same structure, each phase is composed of four integrated Gate Commutated thyristors (IGCTs; each IGCT comprises an anti-parallel diode) and two clamping diodes, and the specific connection mode takes the a phase as an example: t is a unit ofa1、Ta2、Ta3、Ta4The cathodes of more than one IGCT are connected with the anode of the next IGCT in series in sequence, and the clamping diode D1Is electrically connected to Ta1Cathode (T)a2Anode) of the clamping diode D1Is electrically connected to the clamping diode D2Cathode of (2), clamping diode D2Is connected to Ta3Of the heartPole (T)a4Anode of (b). Energy storage capacitor CT1、CT2An energy storage capacitor C arranged on the DC side of the NPC converterT1Positive pole of (3) and the first IGCT (T) of each phase of NPC convertera1、Tb1、Tc1、Tn1) The anodes of the capacitors are all electrically connected, and the energy storage capacitor CT1Cathode and clamping diode Da1、Db1、Dc1、Dn1Positive electrode (i.e. D)a2、Db2、Dc2、Dn2Negative electrodes of) are electrically connected; energy storage capacitor CT2Anode and energy storage capacitor CT1Is electrically connected to the point O, and an energy storage capacitor CT2Negative and fourth IGCT (T) per phase of the NPC convertera4、Tb4、Tc4、Tn4) Are all electrically connected. AC output port of a phase of NPC converter from Ta2And Ta3The anode connecting node of the cascade H-bridge shaping circuit unit is led out and is electrically connected with a phase a sub-module of the cascade H-bridge shaping circuit unit. N-phase T of NPC convertern2And Tn3And is grounded.
As shown in fig. 3, the cascaded H-bridge shaping circuit unit provided in this embodiment has three phases (a phase, b phase, and c phase), each phase has the same structure, each phase is composed of n identical submodules, and the a-phase submodule SMai(i 1-n), b-phase submodule SMbi(i 1-n), c-phase submodule SMci(i is 1 to n). Each sub-module comprises a group consisting of T11、T12、T21、T22Single-phase full-bridge converter formed by four Insulated Gate Bipolar transistors (IGBTs; each IGBT comprises an anti-parallel diode) and energy storage capacitor C arranged on direct current side of the single-phase full-bridge converterH. The specific connection mode is described by taking the phase a as an example: each submodule SMaiSingle-phase full-bridge inverter T with 1-n (i)11Emitter and T of12Are electrically connected together as output port, T21Emitter and T22Are electrically connected together as input ports, an energy storage capacitor CHPositive electrode of (2) and T11、T21Is electrically connected with the collector electrode of the energy storage capacitor CHOf the negative electrodeAnd T12、T22Is electrically connected to the emitter, submodule SMa1The output port of the transformer is connected with a grid-connected point after being connected with a filter inductor L in series, and the voltage of the grid-connected point is
Figure BDA0003659258780000061
Submodule SMa1Is electrically connected to the sub-module SMa2Output port of, remaining submodules SMai(i-3-n) are respectively connected in series in such a way that the input ports of more than one sub-module are electrically connected to the output port of the next sub-module, and the last sub-module SManThe input port of the voltage regulator is electrically connected with the alternating current output port of the phase a in the square wave circuit unit.
On the whole, the control method of the multifunctional arc suppression converter can be summarized as follows: the modulation of the multifunctional arc suppression converter is divided into square wave circuit unit modulation and cascade H-bridge shaping circuit unit modulation, and the output voltage of the multifunctional arc suppression converter
Figure BDA0003659258780000071
For shaped voltage output by cascaded H-bridge shaping circuit units
Figure BDA0003659258780000072
Voltage output from square wave circuit unit
Figure BDA0003659258780000073
The sine wave formed by shaping has the following calculation formula:
Figure BDA0003659258780000074
when the power distribution network is normal, as shown in fig. 4, n phases of the NPC converter in the square wave circuit unit are blocked, and the multifunctional arc suppression converter works in a reactive compensation mode.
When a single-phase ground fault occurs in the distribution network, as shown in fig. 5, the multifunctional arc-suppression converter operates in an arc-suppression mode, and injects arc-suppression current by using one or two phases of non-fault phases to compensate for the capacitance current to ground of the distribution network, so as to suppress the current at the fault point to be 0.
The modulation process of the square wave circuit unit and the cascaded H-bridge shaping circuit unit is explained in detail below.
Firstly, when the power distribution network is normal, the n phases of the NPC converter in the MF-ASC are blocked, the MF-ASC works in a reactive compensation mode, and due to three-phase symmetry, the MF-ASC modulation process is explained in detail by taking the a phase as an example.
1) Square wave circuit cell modulation
The square wave circuit unit adopts the nearest level approximation control, the n phase of the NPC converter is blocked, the a phase, the b phase and the c phase are matched, and the voltage output by the square wave circuit unit in one period
Figure BDA0003659258780000075
With Udc、0、-UdcThree levels. Specifically, as shown in fig. 6, the output reference voltage of the multifunction arc-extinguishing converter is set to
Figure BDA0003659258780000076
In that
Figure BDA0003659258780000077
In the positive half period of (2)
Figure BDA0003659258780000078
Energy storage capacitor C larger than square wave circuit unit direct current sideT1Or CT2At a voltage of (2), i.e.
Figure BDA0003659258780000079
Voltage output by square wave circuit unit
Figure BDA00036592587800000710
Is a positive level voltage Udc(ii) a In that
Figure BDA00036592587800000711
In the negative half period of (c) when
Figure BDA00036592587800000712
Time, square wave circuit unitVoltage of output
Figure BDA00036592587800000713
Is a negative level voltage-UdcIn other cases, the voltage output by the square wave circuit unit
Figure BDA00036592587800000714
Is 0. The switching states of the phase a devices of the NPC converter are shown in table 1 below.
TABLE 1 three-level switch state table
Figure BDA00036592587800000715
Figure BDA0003659258780000081
2) Cascaded H-bridge shaping circuit unit modulation
The cascaded H-bridge shaping circuit unit adopts unipolar carrier phase shift control, and the output shaping reference voltage thereof
Figure BDA0003659258780000082
Output reference voltage of multifunctional arc suppression converter
Figure BDA0003659258780000083
And the voltage output by the square wave circuit unit
Figure BDA0003659258780000084
Calculated as follows:
Figure BDA0003659258780000085
as shown in the figure 7 of the drawings,
Figure BDA0003659258780000086
as the modulation wave of each sub-module, the triangular carrier phase of each sub-module is in turn phase-wiseDifference pi/n, cascaded H-bridge shaping circuit unit output shaping voltage
Figure BDA0003659258780000087
3) MF-ASC hybrid modulation
As shown in fig. 8, the modulation strategy of the MF-ASC is divided into two parts, namely square wave circuit unit modulation and cascaded H-bridge shaping circuit unit modulation, and the shaping voltage output by the cascaded H-bridge shaping circuit unit
Figure BDA0003659258780000088
High-voltage three-level voltage output by square wave circuit unit
Figure BDA0003659258780000089
Shaping to obtain output voltage of MF-ASC
Figure BDA00036592587800000810
Calculated as follows:
Figure BDA00036592587800000811
since the voltage drop across the filter inductance L is small,
Figure BDA00036592587800000812
amplitude approximately equal to the voltage of the grid-connected point
Figure BDA00036592587800000813
The amplitude value.
And secondly, when the single-phase earth fault occurs in the power distribution network, the MF-ASC utilizes one phase or two phases of the non-fault phase to inject arc suppression current to compensate capacitance current of the power distribution network to earth, so that the current of a fault point is suppressed to be 0, and the MF-ASC modulation process is explained in detail by taking a phase-to-earth fault as an example below due to three-phase symmetry.
1) Square wave circuit cell modulation
The square wave circuit unit adopts the nearest level approximation control, n phase of the square wave circuit unit is matched with b and c, and the voltage output by the square wave circuit unit in a period
Figure BDA00036592587800000814
Has 2Udc、Udc、0、-Udc、-2UdcFive levels. Specifically, as shown in fig. 9, the output reference voltage of the multifunction arc-extinguishing converter is set to
Figure BDA00036592587800000815
In that
Figure BDA00036592587800000816
In the positive half period of (1), when
Figure BDA00036592587800000817
And the DC side energy storage capacitor C of the square wave circuit unitT1Or CT2At a voltage of
Figure BDA00036592587800000818
Voltage outputted from square wave circuit unit
Figure BDA00036592587800000819
Is a positive level voltage UdcWhen is coming into contact with
Figure BDA00036592587800000820
Voltage outputted from square wave circuit unit
Figure BDA0003659258780000091
Is a positive level voltage 2Udc(ii) a In that
Figure BDA0003659258780000092
In the negative half period of (c) when
Figure BDA0003659258780000093
Voltage outputted from square wave circuit unit
Figure BDA0003659258780000094
Is a negative level voltage-UdcWhen it comes to
Figure BDA0003659258780000095
Voltage outputted from square wave circuit unit
Figure BDA0003659258780000096
Is a positive level voltage-2Udc(ii) a In other cases, the voltage output by the square wave circuit unit
Figure BDA0003659258780000097
Is 0. Taking the matching of the n-leg and the b-leg as an example, the switching states of the devices are shown in table 2.
TABLE 2 five-level switch state table
Figure BDA0003659258780000098
2) Cascaded H-bridge shaping circuit unit modulation
The cascaded H-bridge shaping circuit unit adopts unipolar carrier phase shift control, and the output shaping reference voltage
Figure BDA0003659258780000099
Output reference voltage of multifunctional arc suppression converter
Figure BDA00036592587800000910
And the voltage output by the square wave circuit unit
Figure BDA00036592587800000911
Calculated as follows:
Figure BDA00036592587800000912
as shown in figure 10 of the drawings,
Figure BDA00036592587800000913
the per unit value of the output voltage is used as the modulation wave of each submodule, the phase difference of the triangular carrier wave of each submodule is pi/n in sequence, and the b phase and the c phase of the cascade H-bridge shaping circuit unit output shaping voltage
Figure BDA00036592587800000914
3) MF-ASC hybrid modulation
As shown in fig. 11, the modulation strategy of the MF-ASC is divided into two parts, namely square wave circuit unit modulation and cascaded H-bridge shaping circuit unit modulation, and the shaping voltage output by the cascaded H-bridge shaping circuit unit
Figure BDA00036592587800000915
High-voltage three-level voltage output by square wave circuit unit
Figure BDA00036592587800000916
Shaping to obtain output voltage of MF-ASC
Figure BDA00036592587800000917
Calculated as follows:
Figure BDA0003659258780000101
since the voltage drop across the filter inductance L is small,
Figure BDA0003659258780000102
amplitude approximately equal to the grid point voltage
Figure BDA0003659258780000103
The amplitude value.
In order to better prove the effectiveness of the multifunctional arc suppression converter and the control method thereof, verification is performed below by combining with an example, taking the example that the withstand voltage of a power electronic device of a submodule of a cascaded H-bridge shaping circuit unit is 1700V, and the direct-current side voltage Uc is 800V. In a 10kV distribution network, the arc suppression device is subjected to line voltage during the suppression of the arc, with a peak value of 14142V. The number of H bridge submodules required by each phase of the traditional cascade H bridge type active arc suppression device is 21, and the number of the H bridge submodules required by three phases is 63.
The invention provides a multifunctional converter, a power electronic device of a square wave circuit unit of the multifunctional converter6500V voltage selection, DC side capacitance voltage Udc1＝Udc24000V. The maximum bearing voltage of the square wave circuit unit is 8000V during arc extinction, so that the maximum bearing voltage of the cascaded H-bridge shaping circuit unit is 6142V, the number of the submodules of each phase of the cascaded H-bridge shaping circuit unit in the MF-ASC is 9, and the number of the submodules is 27 in total for three phases.
Compared with the traditional cascaded H-bridge type active arc suppression device, the MF-ASC hybrid topological structure greatly reduces the number of cascaded H-bridge submodules, and has fewer power electronic devices and direct-current side capacitors, and the active device has higher power density and efficiency.
The above embodiments are preferred implementations of the present invention, and the present invention can be implemented in other ways without departing from the spirit of the present invention.
Some of the figures and descriptions of the present invention have been simplified to provide a convenient understanding of the modifications of the invention relative to the prior art, and to omit elements for clarity, as those skilled in the art will recognize which may also constitute the subject matter of the present invention.

Claims (6)

1. The utility model provides a multi-functional arc extinction converter, includes three-phase cascade H bridge shaping circuit unit, each looks structure is the same in the cascade H bridge shaping circuit unit, all includes a plurality of submodule pieces, its characterized in that: the multifunctional arc suppression converter further comprises a square wave circuit unit which is connected with the cascaded H-bridge shaping circuit unit in series, and the square wave circuit unit is a three-phase four-bridge-arm diode clamp type circuit.
2. A multifunctional arc extinction current transformer according to claim 1, characterized in that: the square wave circuit unit comprises a three-phase four-bridge arm NPC converter and two energy storage capacitors CT1、CT2The NPC converter comprises a phase a, a phase b, a phase c and a phase n, each phase comprises four IGCTs and two clamping diodes, and one IG is more than the four IGCTsThe cathodes of the CTs are electrically connected with the anode of the next IGCT in series in sequence, the cathode of the first clamping diode is electrically connected with the cathode of the first IGCT, the anode of the first clamping diode is connected with the cathode of the second clamping diode, and the anode of the second clamping diode is electrically connected with the cathode of the third IGCT; the energy storage capacitor CT1、CT2An energy storage capacitor C arranged on the DC side of the NPC converterT1The anode of the NPC converter is electrically connected with the anode of the first IGCT of each phase, and the energy storage capacitor CT1The negative electrode of the NPC converter is electrically connected with the positive electrode of the first clamping diode of each phase of the NPC converter, and the energy storage capacitor CT2Anode and energy storage capacitor CT1Is electrically connected to the point O and an energy storage capacitor CT2The negative electrode of the NPC converter is electrically connected with the cathode of the fourth IGCT of each phase; alternating current output ports of the a phase, the b phase and the c phase of the NPC converter are respectively led out from the second IGCT and the third IGCT of the corresponding phases of the NPC converter and are electrically connected with submodules of the corresponding phases in the cascade H-bridge shaping circuit unit, and the second IGCT and the third IGCT of the n phase of the NPC converter are grounded.
3. A multifunctional arc extinction current transformer according to claim 2, characterized in that: the number of each phase of sub-modules of the cascaded H-bridge shaping circuit unit is n, and the sub-modules comprise T11、T12、T21、T22Single-phase full-bridge converter formed by four IGBTs and energy storage capacitor C installed on direct current side of single-phase full-bridge converterH(ii) a In each submodule, a single-phase full-bridge converter T11Emitter and T12Are electrically connected together as output port, T21Emitter and T22Are electrically connected together as input ports, an energy storage capacitor CHPositive electrode and T11、T21Is electrically connected with the collector of the energy storage capacitor CHNegative electrode and T12、T22The emitter of (2) is electrically connected; in the cascaded H-bridge shaping circuit unit, the n submodules of each phase are sequentially connected in series in a way that the input ports of more than one submodule are electrically connected to the output port of the next submodule, and the second submodule is connected in seriesThe output port of one submodule is connected with the filter inductor L in series and then is connected with a grid-connected point, and the input port of the last submodule is electrically connected with the corresponding alternating current output port in the square wave circuit unit.
4. A control method of a multifunctional arc extinction converter according to any one of claims 1 to 3, characterized in that: dividing the modulation of the multifunctional arc suppression converter into square wave circuit unit modulation and cascade H-bridge shaping circuit unit modulation, wherein the multifunctional arc suppression converter outputs voltage
Figure FDA0003659258770000021
For shaped voltage output by cascaded H-bridge shaping circuit units
Figure FDA0003659258770000022
Voltage output from square wave circuit unit
Figure FDA0003659258770000023
The sine wave formed by shaping has the following calculation formula:
Figure FDA0003659258770000024
when the power distribution network is normal, n phases of the NPC converter in the square wave circuit unit are blocked, and the multifunctional arc suppression converter works in a reactive compensation mode;
when a single-phase earth fault occurs in the power distribution network, the multifunctional arc suppression converter works in an arc suppression mode, and one phase or two phases of a non-fault phase are used for injecting arc suppression current to compensate capacitance current of the power distribution network to earth, so that the current of a fault point is suppressed to be 0.
5. The control method of the multifunctional arc suppression converter according to claim 4, characterized in that: when the power distribution network is normal, the modulation processes of the square wave circuit unit and the cascade H-bridge shaping circuit unit are as follows:
1) square wave circuit unit
The square wave circuit unit adopts the nearest level approximation control, the n phase of the NPC converter is blocked, the a phase, the b phase and the c phase are matched, and the voltage output by the square wave circuit unit in a period
Figure FDA0003659258770000025
With Udc、0、-UdcThree levels;
setting the output reference voltage of the multifunctional arc suppression converter to
Figure FDA0003659258770000026
In that
Figure FDA0003659258770000027
In the positive half period of (2)
Figure FDA0003659258770000028
Energy storage capacitor C larger than square wave circuit unit direct current sideT1Or CT2At a voltage of (2), i.e.
Figure FDA0003659258770000029
Voltage output by square wave circuit unit
Figure FDA00036592587700000210
Is a positive level voltage Udc(ii) a In that
Figure FDA00036592587700000211
In the negative half period of (c) when
Figure FDA00036592587700000212
Voltage outputted from square wave circuit unit
Figure FDA00036592587700000213
Is a negative level voltage-UdcIn other cases, the voltage output by the square-wave circuit unit
Figure FDA00036592587700000214
Is 0;
2) cascaded H-bridge shaping circuit unit
The cascaded H-bridge shaping circuit unit adopts unipolar carrier phase shift control, and the output shaping reference voltage thereof
Figure FDA00036592587700000215
Output reference voltage of multifunctional arc suppression converter
Figure FDA00036592587700000216
And the voltage output by the square wave circuit unit
Figure FDA00036592587700000217
Calculated as follows:
Figure FDA00036592587700000218
Figure FDA0003659258770000031
the per unit value of the output voltage is used as the modulation wave of each submodule, the triangular carrier phase of each submodule sequentially differs pi/n, and the cascaded H-bridge shaping circuit unit outputs the shaping voltage
Figure FDA0003659258770000032
6. A multifunctional arc suppression converter according to claim 4 or 5, characterized in that: when a single-phase earth fault occurs in the power distribution network, the modulation processes of the square wave circuit unit and the cascaded H-bridge shaping circuit unit are as follows:
1) square wave circuit unit
The square wave circuit unit adopts the nearest level approximation control, n phase of the square wave circuit unit is matched with b and c, and the voltage output by the square wave circuit unit in a period
Figure FDA0003659258770000033
Has 2Udc、Udc、0、-Udc、-2UdcFive levels;
setting the output reference voltage of the multifunctional arc suppression converter to
Figure FDA0003659258770000034
In that
Figure FDA0003659258770000035
In the positive half period of (1), when
Figure FDA0003659258770000036
And square wave circuit unit direct current side energy storage capacitor CT1Or CT2At a voltage of
Figure FDA0003659258770000037
Voltage outputted from square wave circuit unit
Figure FDA0003659258770000038
Is a positive level voltage UdcWhen is coming into contact with
Figure FDA0003659258770000039
Voltage outputted from square wave circuit unit
Figure FDA00036592587700000310
Is a positive level voltage 2Udc(ii) a In that
Figure FDA00036592587700000311
In the negative half period of (c) when
Figure FDA00036592587700000312
Voltage outputted from square wave circuit unit
Figure FDA00036592587700000313
Is a negative level voltage-UdcWhen it comes to
Figure FDA00036592587700000314
Voltage outputted from square wave circuit unit
Figure FDA00036592587700000315
Is a positive level voltage-2Udc(ii) a In other cases, the voltage output by the square wave circuit unit
Figure FDA00036592587700000316
Is 0;
2) cascaded H-bridge shaping circuit unit
The cascaded H-bridge shaping circuit unit adopts unipolar carrier phase shift control, and the output shaping reference voltage thereof
Figure FDA00036592587700000317
Output reference voltage of multifunctional arc suppression converter
Figure FDA00036592587700000318
And the voltage output by the square wave circuit unit
Figure FDA00036592587700000319
Calculated as follows:
Figure FDA00036592587700000320
Figure FDA00036592587700000321
the per unit value of the output voltage is used as the modulation wave of each submodule, the phase difference of the triangular carrier wave of each submodule is pi/n in sequence, and the b phase and the c phase of the cascade H-bridge shaping circuit unit output shaping voltage
Figure FDA00036592587700000322
CN202210571213.4A 2022-05-24 2022-05-24 Multifunctional arc suppression converter and control method thereof Pending CN114784779A (en)

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CN116073396A (en) * 2023-03-28 2023-05-05 湖南大学 Heterogeneous module hybrid topology method and system for safe and high-quality power supply of power distribution network
CN116111603A (en) * 2023-03-03 2023-05-12 湖南大学 Reactive voltage support and fault active regulation and control composite device for active power distribution network
CN116316514A (en) * 2023-05-05 2023-06-23 广东信通通信有限公司 Intelligent circuit breaker with arc extinction function, control method and power distribution equipment
CN117118262A (en) * 2023-08-17 2023-11-24 江苏科曜能源科技有限公司 High-voltage three-phase four-bridge arm topological structure and inverter

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CN116111603A (en) * 2023-03-03 2023-05-12 湖南大学 Reactive voltage support and fault active regulation and control composite device for active power distribution network
CN116111603B (en) * 2023-03-03 2023-06-09 湖南大学 Reactive voltage support and fault active regulation and control composite device for active power distribution network
CN116073396A (en) * 2023-03-28 2023-05-05 湖南大学 Heterogeneous module hybrid topology method and system for safe and high-quality power supply of power distribution network
CN116054186A (en) * 2023-03-31 2023-05-02 湖南大学 Hybrid multifunctional grid-connected converter system under complex scene and control method
CN116054186B (en) * 2023-03-31 2023-05-30 湖南大学 Hybrid multifunctional grid-connected converter system under complex scene and control method
CN116316514A (en) * 2023-05-05 2023-06-23 广东信通通信有限公司 Intelligent circuit breaker with arc extinction function, control method and power distribution equipment
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