CN113258572A - Flexible multi-state switch and control method - Google Patents

Flexible multi-state switch and control method Download PDF

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Publication number
CN113258572A
CN113258572A CN202010091753.3A CN202010091753A CN113258572A CN 113258572 A CN113258572 A CN 113258572A CN 202010091753 A CN202010091753 A CN 202010091753A CN 113258572 A CN113258572 A CN 113258572A
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China
Prior art keywords
switch
power
state
current
port
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Granted
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CN202010091753.3A
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Chinese (zh)
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CN113258572B (en
Inventor
谢晔源
杨勇
李继红
王宇
段军
黄晓明
陆翌
王朝亮
倪晓军
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State Grid Zhejiang Electric Power Co Ltd
NR Electric Co Ltd
Electric Power Research Institute of State Grid Zhejiang Electric Power Co Ltd
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State Grid Zhejiang Electric Power Co Ltd
NR Electric Co Ltd
Electric Power Research Institute of State Grid Zhejiang Electric Power Co Ltd
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Priority to CN202010091753.3A priority Critical patent/CN113258572B/en
Publication of CN113258572A publication Critical patent/CN113258572A/en
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Publication of CN113258572B publication Critical patent/CN113258572B/en
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    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02JCIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00Circuit arrangements for ac mains or ac distribution networks
    • H02J3/04Circuit arrangements for ac mains or ac distribution networks for connecting networks of the same frequency but supplied from different sources
    • H02J3/06Controlling transfer of power between connected networks; Controlling sharing of load between connected networks
    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02MAPPARATUS 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
    • H02M1/00Details of apparatus for conversion
    • H02M1/32Means for protecting converters other than automatic disconnection
    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02MAPPARATUS 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
    • H02M3/00Conversion of dc power input into dc power output
    • H02M3/22Conversion of dc power input into dc power output with intermediate conversion into ac
    • H02M3/24Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
    • H02M3/28Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
    • H02M3/325Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
    • H02M3/335Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/33569Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements
    • H02M3/33576Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements having at least one active switching element at the secondary side of an isolation transformer
    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02MAPPARATUS 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
    • H02M7/00Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/02Conversion of ac power input into dc power output without possibility of reversal
    • H02M7/04Conversion of ac power input into dc power output without possibility of reversal by static converters
    • H02M7/12Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/21Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M7/217Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M7/219Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only in a bridge configuration
    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02MAPPARATUS 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
    • H02M7/00Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/42Conversion of dc power input into ac power output without possibility of reversal
    • H02M7/44Conversion of dc power input into ac power output without possibility of reversal by static converters
    • H02M7/48Conversion 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
    • H02M7/483Converters with outputs that each can have more than two voltages levels

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Inverter Devices (AREA)

Abstract

The application provides a flexible multi-state switch and a control method: the flexible multi-state switch comprises two chain-link converters; the chain type converter comprises three multilevel converter chains, the three multilevel converter chains are connected end to form an angle connection method, and the end part of the chain type converter is led out to be connected with an alternating current power grid; the multilevel converter chain comprises N four-port power modules and at least one damping unit, wherein N is an integer greater than or equal to 1; the four-port power module consists of a direct current capacitor, a power assembly, a first switch unit and a second switch unit; the direct current capacitor is connected with a power assembly, the power assembly comprises four groups of power semiconductor devices and forms two bridge arms, namely a full-bridge connection mode, and alternating current ends defined as four-port power modules are led out from the middle points of the two bridge arms; one end of the first switch unit is connected with the anode or the cathode of the direct current capacitor, the other end of the first switch unit is connected with one end of the second switch unit, and a first direct current port is led out from the connection point of the first switch unit and the second switch unit; the other end of the second switch unit is defined as a second direct current port.

Description

Flexible multi-state switch and control method
Technical Field
The application relates to the technical field of power electronics, in particular to a flexible multi-state switch and a control method.
Background
With the continuous improvement of the requirements of users on power consumption demand, power quality, power supply reliability and the like, the traditional power supply network is more and more difficult to meet the power supply demand of the users. When one line of the existing power supply and distribution network is overloaded or fails, a power failure in a larger range is often caused. Under the condition of double-bus power supply, the condition that one bus is overloaded and the other bus is lightly loaded to cause unbalanced power load often occurs, and if the two buses are interconnected by using a power electronic technology, the power supply reliability can be improved, and the active power balance can be realized. Meanwhile, in an alternating current-direct current power distribution network, the application range of distributed power generation in a power grid is wider and wider, the distributed power generation gradually becomes effective supplement of a large power grid, a micro grid is formed by distributed power sources, loads and energy storage devices, the types of the distributed power sources, the loads and the energy storage devices are different and comprise direct current or alternating current, the voltage grades and the capacities are different, and how to economically and effectively access the low-voltage units and perform unified management is a problem which is difficult to solve.
In the prior art, a flexible loop closing device constructed by Voltage Source Converters (VSC) based on full-control devices back to back can realize loop closing operation of a power distribution network, improve power supply reliability, and realize mutual transmission of active power, but the cost of the mode is too high; and the interconnection mode is single, only can realize the interconnection between two way middling pressure alternating current power supplies, can't provide the low pressure alternating current-direct current system and insert or realize low pressure alternating current-direct current interconnection. And do not become an economical and effective solution.
Disclosure of Invention
The invention aims to provide a flexible multi-state switch and a flexible alternating current-direct current interconnection system, which can realize mutual support of active power of two paths of alternating current power supplies and achieve the effect of direct current voltage balance control. The invention also provides a corresponding control method.
In order to achieve the above purpose, the solution of the invention is:
a flexible multi-state switch comprising:
two chain-link converters and at least one interconnection module;
the chain type converter comprises three multilevel converter chains, the three multilevel converter chains are connected end to form an angle connection method, and the end part of the chain type converter is led out to be connected with an alternating current power grid;
the multilevel converter chain comprises N four-port power modules and at least one damping unit, wherein N is an integer greater than or equal to 1;
the four-port power module consists of a direct current capacitor, a power assembly, a first switch unit and a second switch unit; the direct current capacitor is connected with the power assembly in parallel, the power assembly comprises four groups of power semiconductor devices to form two bridge arms, namely a full-bridge connection mode, and alternating current ends defined as four-port power modules are led out from the middle points of the two bridge arms; one end of the first switch unit is connected with the anode or the cathode of the direct current capacitor, the other end of the first switch unit is connected with one end of the second switch unit, and a first direct current port is led out from the connection point of the first switch unit and the second switch unit; the other end of the second switch unit is defined as a second direct current port;
the alternating current ends of the four-port power modules are sequentially connected with the alternating current ends of the adjacent four-port power modules; the alternating current ends of the four-port power modules are sequentially connected with the alternating current ends of the adjacent four-port power modules; the second direct current port of the four-port power module is connected with the first direct current port of the adjacent four-port power module;
the damping unit comprises a third switch unit and a damping resistor which are connected in parallel, and the damping unit is connected with the alternating current end of the four-port power module in series;
and two ends of the interconnection module are respectively connected with direct current capacitors positioned on any different four-port power modules of the two chain-type current converters.
As a further preferable aspect of the present invention, the first switch unit includes a first switch, and the second switch unit includes a second switch; the first switch and the second switch are power semiconductor devices or mechanical switches.
In a further preferred embodiment of the present invention, the first switch is a power semiconductor device, and the second switch is a diode.
As a further preferable aspect of the present invention, the first switch unit and the second switch unit further include a current limiting resistor or/and a fuse, and the resistor or/and the fuse are connected in series with the first switch and the second switch.
As a further preferable scheme of the present invention, the interconnection module is composed of an interconnection unit dc-ac converter, an isolation transformer, and an interconnection unit ac-dc converter; the interconnection unit DC-AC converter converts DC into AC and is connected with the primary side of the isolation transformer; the secondary side of the isolation transformer is connected with the alternating current side of the interconnection unit alternating current-direct current converter, and the interconnection unit alternating current-direct current converter converts alternating current into direct current.
The invention also provides a control method of the flexible multi-state switch, which comprises the following steps:
step 1: uncontrolled charging of the chain converter;
step 2: locking all power semiconductor devices in the four-port power module;
and step 3: unlocking a full-bridge power semiconductor device in the four-port power module until the highest direct-current capacitor voltage rises to Vc 1;
and 4, step 4: unlocking a first switch unit and a second switch unit in the four-port power module, and balancing all direct-current capacitor voltages to Vc 2;
and 5: unlocking the interconnection module, and setting the active power transmission fixed value and direction of the two chain converters;
step 6: the two chain-type current converters respectively and independently compensate the electric energy quality of the system connection point.
As a further preferred aspect of the present invention, said Vc1 is greater than Vc 2.
As a further preferable scheme of the present invention, when a part of four-port power modules of the flexible multi-state switch fails, the corresponding first switch unit is turned off, and the second switch is kept on;
the invention also provides another control method of the flexible multi-state switch, wherein the flexible multi-state switch comprises a plurality of operation states: including electric energy management state, automatic voltage-sharing state, active controllable transmission state, short-circuit current transfer state, passive power supply state, flexible many state switch judges or accepts external instruction by oneself, switches between various states:
when the flexible multi-state switch normally operates, the two chain type current converters in the flexible multi-state switch are in an automatic voltage-sharing state;
when the power quality of a power grid compensation point connected with the chain type current converter exceeds an allowable range, the chain type current converter is independently switched into a power management state;
when an external active power transmission instruction is received, the two chain type current converters are switched into an active controllable transmission state;
when a power grid connected with any one chain type current converter fails, the two chain type current converters are switched into a short-circuit current transfer state to share fault current;
when the power grid compensation point connected with the chain type converter loses power, the chain type converter is switched into a passive power supply state.
The invention provides another control method of the flexible multi-state switch, which comprises the following steps: when the current flowing through the multilevel converter chain exceeds a threshold value, the third switch unit in the damping unit is separated.
Has the advantages that:
(1) the technical scheme provided by the application is as follows: the interconnection module between the four-port power modules of the converter chains in the two chain type converters realizes the active power transmission of the two converters; the four-port power modules in the chain type converter form a closed loop in a corner, and when the direct current voltage is unbalanced, the four-port power modules can automatically realize the balanced adjustment of the direct current voltage, so that the interconnection modules among the four-port power modules can be arranged at will; that is, when two chain-link converters are interconnected, when there is active power transmission, a local dc capacitor voltage imbalance may be internally balanced by each chain-link converter.
(2) The damping unit is further configured, when the fact that the current flowing through the commutation chain is too large is detected, the third switching unit is separated, the overcurrent can be effectively limited, and the commutation chain is protected.
(3) The technical scheme provided by the application provides multiple states, and provides a switching method of the multiple states, and besides the functions of voltage sharing and active power transmission, the switching method also has multiple functions of improving the quality of electric energy, limiting fault current, passive inversion and the like, and improves the reliability of the regional power distribution network.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
Fig. 1 is a schematic structural diagram of a flexible multi-state switch provided in an embodiment of the present application;
FIG. 2 is a schematic diagram illustrating a detailed structure of a flexible multi-state switch provided in an embodiment of the present application;
fig. 3A is a schematic diagram of a four-port power module according to an embodiment of the present disclosure;
fig. 3B is a second schematic diagram of a four-port power module according to an embodiment of the present invention;
FIG. 4 is a schematic diagram of a damping unit provided in an embodiment of the present application;
FIG. 5 is a schematic diagram of an interconnect module according to an embodiment of the present disclosure;
fig. 6 is a flexible multi-state switch control method provided in an embodiment of the present application.
Reference numerals:
1. a multilevel converter chain; 2. a four-port power module; 3. a chain-link converter; 4. a damping unit; 5. an interconnect module;
Detailed Description
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some, but not all, embodiments of the present application. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
It should be understood that the terms "first," "second," "third," "fourth," and the like in the claims, the description, and the drawings of the present application are used for distinguishing between different objects and not for describing a particular order. The term "comprises/comprising" when used in the specification and claims of this application is taken to specify the presence of stated features, integers, steps, operations, elements, and/or components, but does not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.
The invention provides a flexible multi-state switch, fig. 1 is a schematic structural diagram of the flexible multi-state switch provided in the embodiment of the present application, and fig. 2 is a detailed structural diagram of the flexible multi-state switch provided in the embodiment of the present application. The method comprises the following steps:
two chain-link converters 3 and at least one interconnect module 5;
the chain type converter 3 comprises three multilevel converter chains 1, the three multilevel converter chains are connected end to form an angle connection method, and the end parts of the three multilevel converter chains are led out to be connected with an alternating current power grid; the multilevel converter chain comprises N four-port power modules 2 and at least one damping unit 4, wherein N is an integer greater than or equal to 1;
as shown in fig. 3A, the four-port power module is composed of a dc capacitor, a power module, a first switching unit DK1 and a second switching unit DK 2; the direct current capacitor is connected in parallel with the power assembly, the power assembly comprises four groups of power semiconductor devices to form two bridge arms, namely a full-bridge connection mode, alternating current ends defined as four-port power modules are led out from the midpoints of the two bridge arms and are respectively a port D1 and a port D2; one end of the first switch unit is connected with the anode or the cathode of the direct current capacitor, the other end of the first switch unit is connected with one end of the second switch unit, and a first direct current port D3 is led out from the connection point of the first switch unit and the second switch unit; the other end of the second switch unit is defined as a second direct current port D4;
fig. 3A is an embodiment in which one end of the first switch unit is connected to the positive electrode of the dc capacitor, and fig. 3B is an embodiment in which one end of the first switch unit is connected to the negative electrode of the dc capacitor.
The alternating current ends of the four-port power modules are sequentially connected with the alternating current ends of the adjacent four-port power modules; the second direct current port of the four-port power module is connected with the first direct current port of the adjacent four-port power module;
as shown in fig. 4, the damping unit 4 includes a third switching unit DK3 and a damping resistor R2, the third switching unit is connected in parallel with the damping resistor, and the damping unit formed by the third switching unit and the damping resistor is connected in series with the ac terminal of the four-port power module;
and two ends of the interconnection module 5 are respectively connected with direct current capacitors positioned on any different four-port power modules of the two chain-type converters.
Wherein the first switch unit comprises a first switch, and the second switch unit comprises a second switch; the first switch and the second switch are power semiconductor devices or mechanical switches;
preferably, the first switch is a power semiconductor device, and the second switch is a diode.
The first switch unit and the second switch unit also comprise current limiting resistors or/and fuses, and the resistors or/and fuses are connected with the first switch and the second switch in series.
As shown in fig. 5, the dc interconnection unit 5 is composed of an interconnection unit dc-ac converter 15, an isolation transformer 17 and an interconnection unit ac-dc converter 16; the interconnection unit DC-AC converter converts DC into AC and is connected with the primary side of the isolation transformer; the secondary side of the isolation transformer is connected with the alternating current side of the interconnection unit alternating current-direct current converter, and the interconnection unit alternating current-direct current converter converts alternating current into direct current. In this embodiment, a capacitor is further included between the interconnection unit dc-ac converter and the primary winding, and a capacitor and an inductor are further included between the secondary winding and the interconnection unit dc-ac converter.
The invention also provides a control method of the flexible multi-state switch, which comprises the following steps:
the control method comprises the following steps:
step 1: uncontrolled charging of the chain-type current converter;
step 2: locking all power semiconductor devices in the four-port power module;
and step 3: unlocking a full-bridge power semiconductor device in the four-port power module until the highest direct-current capacitor voltage rises to Vc 1;
and 4, step 4: unlocking a first switch unit and a second switch unit in the four-port power module, and balancing all direct-current capacitor voltages to Vc 2;
and 5: unlocking the interconnection module, and setting the active power transmission fixed value and direction of the two chain converters;
step 6: the two chain-type current converters respectively and independently compensate the electric energy quality of the system connection point.
Wherein the Vc1 is greater than Vc 2.
When the flexible multi-state switch has partial four-port power module faults, the corresponding first switch unit is switched off, and the second switch is kept switched on;
the flexible multi-state switch comprises a plurality of operating states: including electric energy management state, automatic voltage-sharing state, active controllable transmission state, short-circuit current transfer state, passive power supply state, flexible many state switch judges or accepts external instruction by oneself, switches between various states: as shown in fig. 6:
when the flexible multi-state switch normally operates, the two chain type current converters in the flexible multi-state switch are in an automatic voltage-sharing state;
when the power quality of a power grid compensation point connected with the chain type current converter exceeds an allowable range, the chain type current converter is independently switched into a power management state;
when an external active power transmission instruction is received, the two chain type current converters are switched into an active controllable transmission state;
when a power grid connected with any one chain type current converter fails, the two chain type current converters are switched into a short-circuit current transfer state to share fault current;
when the power grid compensation point connected with the chain type converter loses power, the chain type converter is switched into a passive power supply state.
Wherein the third switching unit in the damping unit is separated when the current flowing through the multilevel converter chain exceeds a threshold value.
The foregoing detailed description of the embodiments of the present application has been presented to illustrate the principles and implementations of the present application, and the description of the embodiments is only intended to facilitate the understanding of the methods and their core concepts of the present application. Meanwhile, a person skilled in the art should, according to the idea of the present application, change or modify the embodiments and applications of the present application based on the scope of the present application. In view of the above, the description should not be taken as limiting the application.

Claims (10)

1. A flexible multi-state switch, comprising:
two chain-link converters and at least one interconnection module;
the chain type converter comprises three multilevel converter chains, the three multilevel converter chains are connected end to form an angle connection method, and the end part of the chain type converter is led out to be connected with an alternating current power grid;
the multilevel converter chain comprises N four-port power modules and at least one damping unit, wherein N is an integer greater than or equal to 1;
the four-port power module consists of a direct current capacitor, a power assembly, a first switch unit and a second switch unit; the direct current capacitor is connected with the power assembly in parallel, the power assembly comprises four groups of power semiconductor devices to form two bridge arms, namely a full-bridge connection mode, and alternating current ends defined as four-port power modules are led out from the middle points of the two bridge arms; one end of the first switch unit is connected with the anode or the cathode of the direct current capacitor, the other end of the first switch unit is connected with one end of the second switch unit, and a first direct current port is led out from the connection point of the first switch unit and the second switch unit; the other end of the second switch unit is defined as a second direct current port;
the alternating current ends of the four-port power modules are sequentially connected with the alternating current ends of the adjacent four-port power modules; the alternating current ends of the four-port power modules are sequentially connected with the alternating current ends of the adjacent four-port power modules; the second direct current port of the four-port power module is connected with the first direct current port of the adjacent four-port power module;
the damping unit comprises a third switch unit and a damping resistor which are connected in parallel, and the damping unit is connected with the alternating current end of the four-port power module in series;
and two ends of the interconnection module are respectively connected with direct current capacitors positioned on any different four-port power modules of the two chain-type current converters.
2. The flexible multi-state switch of claim 1, wherein the first switch unit comprises a first switch and the second switch unit comprises a second switch; the first switch and the second switch are power semiconductor devices or mechanical switches.
3. The flexible multi-state switch of claim 1, wherein the first switch is a power semiconductor device and the second switch is a diode.
4. The flexible multi-state switch of claim 2, wherein the first and second switch units further comprise current limiting resistors and/or fuses, and the resistors and/or fuses are connected in series with the first and second switches.
5. The flexible multi-state switch according to claim 1, wherein the interconnection module is composed of an interconnection unit dc-ac converter, an isolation transformer and an interconnection unit ac-dc converter; the interconnection unit DC-AC converter converts DC into AC and is connected with the primary side of the isolation transformer; the secondary side of the isolation transformer is connected with the alternating current side of the interconnection unit alternating current-direct current converter, and the interconnection unit alternating current-direct current converter converts alternating current into direct current.
6. A control method of the flexible multi-state switch according to any one of claims 1 to 5, wherein the control method comprises the following steps:
step 1: uncontrolled charging of the chain converter;
step 2: locking all power semiconductor devices in the four-port power module;
and step 3: unlocking a full-bridge power semiconductor device in the four-port power module until the highest direct-current capacitor voltage rises to Vc 1;
and 4, step 4: unlocking a first switch unit and a second switch unit in the four-port power module, and balancing all direct-current capacitor voltages to Vc 2;
and 5: unlocking the interconnection module, and setting the active power transmission fixed value and direction of the two chain converters;
step 6: the two chain-type current converters respectively and independently compensate the electric energy quality of the system connection point.
7. A control method of the flexible multi-state switch according to claim 6, wherein the Vc1 is larger than Vc 2.
8. The method for controlling the flexible multi-state switch according to claim 6, wherein when the flexible multi-state switch has a partial four-port power module fault, the corresponding first switch unit is turned off, and the second switch unit is turned on.
9. A control method of a flexible multi-state switch according to any one of claims 1 to 5, wherein the flexible multi-state switch comprises a plurality of operation states: including electric energy management state, automatic voltage-sharing state, active controllable transmission state, short-circuit current transfer state, passive power supply state, flexible many state switch judges or accepts external instruction by oneself, switches between various states:
when the flexible multi-state switch normally operates, the two chain type current converters in the flexible multi-state switch are in an automatic voltage-sharing state;
when the power quality of a power grid compensation point connected with the chain type current converter exceeds an allowable range, the chain type current converter is independently switched into a power management state;
when an external active power transmission instruction is received, the two chain type current converters are switched into an active controllable transmission state;
when a power grid connected with any one chain type current converter fails, the two chain type current converters are switched into a short-circuit current transfer state to share fault current;
when the power grid compensation point connected with the chain type converter loses power, the chain type converter is switched into a passive power supply state.
10. A control method for a flexible multi-state switch according to any of claims 1-5, characterized in that the third switching unit of the damping unit is disconnected when the current through the multilevel converter chain exceeds a threshold value.
CN202010091753.3A 2020-02-13 2020-02-13 Flexible multi-state switch and control method Active CN113258572B (en)

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* Cited by examiner, † Cited by third party
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CN110247418A (en) * 2019-07-08 2019-09-17 南京南瑞继保电气有限公司 Alternating current-direct current mixing power distribution network and Control experiment method based on flexible multimode switch

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CN114156874A (en) * 2021-11-25 2022-03-08 南京南瑞继保电气有限公司 Flexible multi-state switch device, multi-state switching method and alternating current system

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