CN113889984A - Direct-current fault current limiter suitable for self-clearing MMC type direct-current distribution network and control method - Google Patents

Direct-current fault current limiter suitable for self-clearing MMC type direct-current distribution network and control method Download PDF

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Publication number
CN113889984A
CN113889984A CN202111144569.1A CN202111144569A CN113889984A CN 113889984 A CN113889984 A CN 113889984A CN 202111144569 A CN202111144569 A CN 202111144569A CN 113889984 A CN113889984 A CN 113889984A
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current
bridge arm
fault
direct
direct current
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Chinese (zh)
Inventor
吕慧婕
何佳伟
李斌
吴通华
戴魏
姚刚
洪丰
李新东
侯小凡
吴丹
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Tianjin University
NARI Group Corp
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Tianjin University
NARI Group Corp
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Priority to CN202111144569.1A priority Critical patent/CN113889984A/en
Publication of CN113889984A publication Critical patent/CN113889984A/en
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
    • H02H7/26—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured
    • H02H7/268—Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured for dc systems
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
    • H02H3/02—Details
    • H02H3/025—Disconnection after limiting, e.g. when limiting is not sufficient or for facilitating disconnection
    • 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
    • H02H9/02—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess current
    • H02H9/025—Current limitation using field effect transistors
    • 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
    • H02J3/36—Arrangements for transfer of electric power between ac networks via a high-tension dc link
    • Y—GENERAL 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
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/60—Arrangements for transfer of electric power between AC networks or generators via a high voltage DC link [HVCD]

Abstract

The invention discloses a direct current fault current limiter and a control method suitable for self-clearing an MMC type direct current distribution network, wherein the direct current fault current limiter comprises an H-bridge circuit, a direct current reactor, a current limiting resistor, a main circuit breaker and a direct current circuit; when the direct-current fault current limiter working in a normal operation state detects a direct-current fault, the IGBT in the main circuit breaker is immediately switched on, a switching-on signal is applied to the quick mechanical switch, and the IGBT in the load branch is locked, so that the fault current is converted from the load branch to the main circuit breaker, and the preparation is made for dissipating fault energy; after entering a fault point isolated state; and the current limiter is recovered to supply power to the whole direct current distribution network. Compared with the prior art, the method can delay the development speed of the direct current fault, realize effective coordination between fault current limiting, protection and cutoff and ensure reliable fault ride-through of the residual network; and a self-adaptive direct current fault current-limiting control strategy is realized.

Description

Direct-current fault current limiter suitable for self-clearing MMC type direct-current distribution network and control method
Technical Field
The invention relates to the field of direct current transmission/distribution/micro-grid, in particular to a self-adaptive direct current fault current limiter suitable for self-clearing an MMC type direct current distribution network and a control strategy thereof.
Background
When a direct-current power distribution system has a direct-current fault, the capacitors of the submodules release electric energy to the fault point, so that bridge arm current and direct-current line current rise rapidly, and the safety and reliability of normal operation are seriously threatened. In this case the faulty cable should be isolated quickly. Typical fault isolation methods include three methods, namely an Alternating Current Circuit Breaker (ACCB), a direct current circuit breaker and a self-cleaning converter topology.
Although fault isolation by using the ACCB is simple and convenient, the method is easy to realize in engineering practice; however, the trip time of the ACCB is generally 2-3 ac cycles, and the requirements of selectivity and rapidity of dc grid fault isolation cannot be met. In addition, it may trigger all ACCBs to trip, resulting in system outage, and the power supply reliability and robustness of the dc grid is not guaranteed.
The high-speed large-capacity direct current breaker is difficult to manufacture and high in cost. The larger demand for the direct current circuit breaker can seriously restrict the large-scale engineering application of the direct current circuit breaker.
By improving the sub-module topology of the Modular Multilevel Converter (MMC), the reverse polarity sub-module capacitor is put into a direct current fault current path, and the direct current fault current can be quickly cleared. Some topologies and control methods are presented in the open literature: the topological structure represented by The full-bridge submodule (FBSM), The Clamping Double Submodule (CDSM) and The like in The document of The term of MMC topologies and The term DC fault current blocking strategies in DC grid can adopt The control strategy of The traditional MMC, and The engineering application of The topological structure is relatively mature; the document "The alternative arm converter: a new hybrid multilevel converter with DC-fault blocking capability" describes an Alternate Arm Multilevel Converter (AAMC) and a Hybrid Cascade Multilevel Converter (HCMC), and The steady-state control of a DC system can also be realized through The coordination of a switch and a shaping circuit. In engineering practice, in addition to fault isolation capability, other factors should be considered including performance of the isolation capability, investment, and power loss.
The classical direct current fault current limiting technology is to directly configure a direct current reactor. However, it deteriorates the dynamic characteristics and operational stability of the system and reduces the speed of clearing the fault current. The current limiter based on the power electronic device combines the advantages of the power electronic device and the mechanical switch, and has wide application prospect in the field of distributed direct-current power grids. In order to overcome the drawback of the use of a current-limiting inductor to suppress the attenuation of the fault current, the document Analysis of the fault current limiting requirement and design of the bridge-type FCL in the multi-terminal DC grid describes a bridge current limiter, which consists of an H-bridge consisting of a diode and a current-limiting branch comprising a current-limiting inductor and a DC bias supply. The special topological structure can reduce the passive influence of the direct current reactors on the conventional performance and the fault current clearing period of the direct current power grid to the maximum extent. However, under normal operating conditions, the load current constantly flows through the diode string, increasing power losses, which is not negligible in the industrial field. A hybrid current-limiting circuit (HCLC) is disclosed in the document "hybrid current-limiting circuit for DC line fault in multi-terminal VSC-HVDC system", the inductance of which is connected in parallel with an Energy Dissipation Circuit (EDC). The EDC consists of a thyristor switch connected to a DC resistor. The thyristor switch is always kept off until the DCCB trips, and the direct-current resistor and a lightning arrester of the direct-current breaker absorb fault energy together, so that the isolation speed of fault current is greatly improved. The document "Topology modeling and Design of a Novel Magnetic Coupling Fault Current Limiter for VSC DC Grids" discloses a Magnetic Coupling Fault Current Limiter, which is composed of a transformer and a plurality of power electronic switch modules. Compared with direct-mounted direct current inductors, the direct-mounted direct current inductor has good current suppression effect and lower impedance. However, the larger reactor and more parallel branches in the MCFCL cause additional costs and losses as a whole.
Disclosure of Invention
The invention provides a direct current fault current limiter and a control method suitable for self-clearing MMC type direct current distribution network, and aims to solve the problems that the current flexible direct current system protection and the action speed of a breaker can not ensure the reliable fault ride-through of a residual network after a direct current fault, the current limiting technology can cause adverse effects on the system and can not realize the matching coordination with the current breaking function, and the like, and a self-adaptive direct current fault recovery control strategy is realized.
The invention is realized by adopting the following technical scheme:
a direct current fault current limiter suitable for self-clearing an MMC type direct current distribution network comprises an H-bridge circuit, a direct current reactor, a current limiting resistor, a main circuit breaker and a direct current circuit; n diodes are connected in series to form a first bridge arm to a fourth bridge arm, the first bridge arm is connected with the second bridge arm in series, and the third bridge arm is connected with the fourth bridge arm in series; a series branch formed by the first bridge arm and the second bridge arm and a series branch formed by the third bridge arm and the fourth bridge arm are connected in parallel to form the H-bridge circuit; the direct current reactor and the direct current resistor which are connected in parallel form a series circuit with the main circuit breaker, and two ends of the series circuit are respectively connected to a public connection point of the first bridge arm and the third bridge arm and a public connection point of the second bridge arm and the fourth bridge arm;
the main circuit breaker specifically comprises an IGBT string connected in parallel, a load branch formed by connecting a quick mechanical switch and a load switch in series and a lightning arrester; the direct current lines are respectively connected with the common connection points of the first bridge arm and the second bridge arm and the common connection points of the third bridge arm and the fourth bridge arm.
A DC fault control method suitable for self-cleaning a DC fault current limiter of an MMC type DC distribution network specifically comprises the following steps
Step 1, under a normal operation state, the first bridge arm and the fourth bridge arm are conducted, an IGBT string in a main circuit breaker is locked, a quick mechanical switch is closed, a load branch is conducted, and a direct-current line current idcThe current flows through the first bridge arm, the direct current reactor, the load branch and the fourth bridge arm, the current-limiting resistor is bypassed by the direct current reactor, and the second bridge arm and the third bridge arm are turned off;
step 2, when the direct current fault is detected, the IGBT in the main circuit breaker is immediately conducted, a conducting signal is applied to the quick mechanical switch, and the IGBT in the load branch is locked, so that the fault current is converted from the load branch to the main circuit breaker, and the preparation is made for dissipating the fault energy; then, reverse polarity capacitance voltage is applied to a fault current circuit, fault current charges a capacitor, the fault current is rapidly attenuated, when the fault current is zero, the reverse clamping effect of a diode clamps the fault current to be zero, and rapid clearing of the fault current is realized;
step 3, after the fault point is in an isolated state, the continuous current of the direct current reactor generates reverse voltage, so that the second bridge arm and the fourth bridge arm are conducted, the continuous current generated by the direct current reactor only flows in the second bridge arm and the fourth bridge arm, and after the fault current is limited, the direct current reactor is bypassed from a fault circuit;
and 4, restoring the current limiter to supply power to the whole direct-current power distribution network: first turn off the IGBT, i of the main breakerLThe rapid decrease, the recovery process is as follows:
(1) when the main breaker IGBT is disconnected, when idc<iLAt/2, idcDirectly flows through a third bridge arm and a fourth bridge arm;
(2)iLcontinuously decrease, idcRises rapidly when idc≥iLA/2 and iL/2<IdcNWhen the bridge arm three is not conducted, iLThe current can only flow through a second bridge arm and a fourth bridge arm; in this case, the influence of the recovery process of the current limiter on the dc system is still small;
(3) when i isL＝IdcNWhen the direct current fault current limiter is completely recovered, preparing for the next fault;
wherein, IdcNIs the rated current of the DC line iLIs the current flowing through the DC reactor, IdcIs the current flowing through the dc line.
Compared with the prior art, the invention has the advantages that: .
1) The direct current fault development speed can be delayed, effective coordination between fault current limiting, protection and cutoff is realized, and reliable fault ride-through of the residual network is ensured;
2) reduces the requirements on the protective action speed and the breaking current and speed of the mechanical switch
3) And a self-adaptive direct current fault current-limiting control strategy is realized.
Drawings
FIG. 1 is a DC fault current limiter topology suitable for self-clearing MMC type DC distribution networks of the present invention;
fig. 2 is an exemplary diagram of the installation position of a dc fault current limiter suitable for self-cleaning an MMC type dc distribution network in a multi-terminal flexible dc power grid according to the present invention;
fig. 3 is a schematic diagram of the working principle of the dc fault current limiter suitable for the MMC type dc power distribution network of the present invention.
Reference numerals:
1. 2, 3, 4, 5, 6, a flow restrictor.
Detailed Description
The frame structure, function and function of the present invention will be described in detail below with reference to the accompanying drawings.
The invention relates to a direct current fault current limiter topological structure suitable for self-clearing MMC type direct current distribution network and a control strategy thereof, which specifically comprises the following contents:
as shown in fig. 1, a topology structure diagram of a dc fault current limiter suitable for self-clearing an MMC dc distribution network according to the present invention includes a first bridge arm to a fourth bridge arm formed by connecting N diodes in series (the size of N can be determined by referring to a parameter determination principle of a conventional current limiter), wherein: the bridge arm I and the bridge arm II are connected in series, the bridge arm III and the bridge arm IV are connected in series, and a series branch formed by the bridge arm I and the bridge arm II and a series branch formed by the bridge arm III and the bridge arm IV are connected in parallel to form an H-bridge circuit. The direct current reactor is connected with the direct current resistor in parallel and then connected with the main circuit breaker in series, two ends of the series circuit are respectively connected to a public connection point of a first bridge arm and a third bridge arm and a public connection point of a second bridge arm and a fourth bridge arm, and the main circuit breaker specifically comprises an IGBT string, a load branch formed by connecting a quick mechanical switch and a load switch in series and a lightning arrester; and the direct current lines are respectively connected with the common connection points of the first bridge arm and the second bridge arm and the common connection points of the third bridge arm and the fourth bridge arm.
Fig. 2 is a diagram illustrating an example of the installation position of the current limiter in the multi-terminal flexible dc power grid. The installation position of the current limiter of the invention in a multi-terminal flexible dc grid is shown, i.e. the converter station outlet and both ends of the dc line. For example, each of 1, 2, 3, 4, 5, and 6 in the drawings is a flow restrictor.
Fig. 3 is a schematic diagram of the working principle of the dc fault current limiter suitable for self-cleaning the MMC dc distribution network according to the present invention. The self-adaptive current limiting capability of the invention is embodied in that the current limiting resistor is bypassed when the direct current reactor is in normal operation, and the stability of a direct current power grid is not greatly influenced. When a fault occurs, the direct current reactor and the resistor are automatically connected to a fault branch circuit to limit fault current.
In the normal operating state as shown in fig. 3 (a): at the moment, the diodes of the first bridge arm and the fourth bridge arm are in a conducting state, the IGBT string in the main breaker is locked, the quick mechanical switch is closed, and the load branch is conducted. Straight barCurrent of the current system idcThe current flows through the first bridge arm, the direct current reactor, the load branch and the fourth bridge arm. Specifically, the dc resistance is bypassed by the dc reactor, and the second and third arms are turned off by the back voltage.
In the dc fault condition shown in fig. 3 (b): at this time, the fault current rapidly rises. The DC reactor and the DC resistor together instantaneously limit the fault current. Studies have shown that the main factor limiting the recovery speed of the current limiter is the switching speed of the fast mechanical switch, and therefore "pre-action" strategies have been proposed to reduce the recovery time of the current limiter. Specifically, when a fault is detected, the IGBTs in the main breaker immediately conduct. Meanwhile, a conducting signal is applied to the quick mechanical switch to lock the IGBT in the load conversion branch circuit. Thus, the fault current is commutated from the load branch to the main breaker, ready for dissipating fault energy.
The adaptive dc fault current limiter of the invention, suitable for self-clearing an MMC type dc power distribution network, is locked in a few milliseconds when a dc fault is detected. Then, a reverse polarity capacitor voltage is applied to the fault current circuit, and the fault current charges the capacitor, so that the fault current is rapidly attenuated. When the fault current is zero, the reverse clamping effect of the diode clamps the fault current to be zero, and the fault current is quickly cleared.
In the state where the fault point is isolated as shown in fig. 3 (c), the continuous current of the dc reactor generates a reverse voltage, and the arm two and the arm four are turned on. The follow-up current generated by the dc reactor flows only inside the fault current limiter FCL, so that the dc reactor is bypassed from the fault circuit after the fault current limiting is completed. In particular, the adaptive dc fault current limiter according to the invention, which is suitable for self-clearing MMC dc power distribution networks, does not need to consume the energy stored in the dc reactor, since the continuous current of the dc reactor flows inside the current limiter, which can be considered as separating the energy in the reactor from the dc line. The isolation speed of the proposed current limiter is therefore much faster compared to a dc reactor installed directly in a dc system. This important feature facilitates fast restoration of healthy grid and fault line insulation characteristics.
When the fault point is isolated, the self-cleaning converter needs to recover to supply power to the whole direct current distribution network. Meanwhile, the continuous current in the direct current reactor needs to be restored to a rated value IdcN。IdcNIs the rated current of the DC line iLIs the current flowing through the dc reactor. Under normal operation and current limiting conditions, IdcN＝iL. Due to the fault clearing phase, the reverse polarity of the capacitor in the self-clearing converter is switched into the fault loop idcAnd rapidly decreases. However, iLAnd current flows in the current limiter only through the second bridge arm and the fourth bridge arm, and because the on-state resistance of the power electronic device is very small and can be ignored, the loop has almost no impedance. Thus, iLSlow decay, at the beginning of the recovery process, iLIs much larger than idcThe value of (c).
In the recovery state shown in FIG. 3 (d), iLThe recovery process of (1), i.e. the recovery process of the current limiter, is to turn off the IGBT of the main breaker first, the energy stored in the dc reactor is dissipated through the arrester and the dc resistor, respectivelyLDecreases rapidly. Before the recovery process, the current of the dc line is 0, since the fault energy has been absorbed by the capacitor of the self-clearing inverter. When the current limiter enters the recovery state, iLThe average distribution is in the branch composed of the first bridge arm and the third bridge arm and the branch composed of the second bridge arm and the fourth bridge arm. The flow restrictor recovery process is as follows:
(1) when the main breaker IGBT is disconnected, when idc<iLAt/2, idcDirectly flows through a third bridge arm and a fourth bridge arm;
(2) in the recovery process, iLContinuously decrease, idcRises rapidly when idc≥iLA/2 and iL/2<IdcNWhen the bridge arm three is not conducted, iLThe current can only flow through a second bridge arm and a fourth bridge arm; in this case, the influence of the recovery process of the current limiter on the dc system is still small;
(3) when i isL＝IdcNIn time, the IGBT of the load branch current conversion link is conductedAnd (3) closing the quick mechanical switch by a signal, and turning off the IGBT of the main breaker, so that the current limiter is completely recovered, and preparation is made for the next fault.
The direct-current fault current limiter and the control method which are suitable for the MMC type direct-current power distribution network and designed by the invention are suitable for a multi-end flexible direct-current power grid, in particular to a direct-current power distribution and direct-current micro-power grid with lower voltage level. Compared with the current breaking by directly utilizing a direct current reactor to limit current and utilizing a traditional direct current solid-state circuit breaker, the current limiter mainly has the following advantages:
1) when the current limiter normally operates, the internal resistance of the current limiter is equivalent to the bypass of a direct current reactor for an external circuit, so that the current limiter does not have adverse effects on the transient response characteristic, stability, efficiency and other aspects of a direct current system, and the circuit design and the control strategy are simple.
2) After the direct current fault, before the self-clearing type converter is locked, the direct current reactor and the direct current resistor can be quickly and automatically connected into a fault loop to play a current limiting role, so that the rising of fault current and the falling of direct current voltage are effectively limited, the development speed of the direct current fault is delayed, and the requirement on the action speed of a mechanical switch is lowered; the reliable crossing of the residual network before the fault is cut off is ensured, and sufficient time is provided for protection and isolation.
3) During fault current clearing, the dc reactor is momentarily/automatically bypassed from the fault loop due to the reverse voltage generated by the continuous current of the dc reactor. The self-cleaning MMC converter station only needs to absorb the energy in the fault loop, thereby greatly accelerating the topology recovery speed provided by the invention, enabling the remaining network to quickly recover normal operation and the fault line to quickly recover insulation.
4) After the fault point disappears or is processed, the fault line can be instantaneously superposed, and the system can immediately start to recover to the running state before the fault; the direct current breaker can be quickly restored to a normal operation state, the processing capacity of secondary faults is guaranteed, and the recovery process of the direct current breaker does not have any influence on the recovery speed of the system.
5) The current limiter has lower threshold values for the voltage, the current and the lightning arrester capacity of the power electronic device, and only needs to bear the current during protection action, thereby greatly reducing the investment cost and the conduction loss.

Claims (3)

1. A direct current fault current limiter suitable for self-clearing an MMC type direct current distribution network is characterized in that the current limiter comprises an H-bridge circuit, a direct current reactor, a current limiting resistor, a main circuit breaker and a direct current circuit; n diodes are connected in series to form a first bridge arm to a fourth bridge arm, the first bridge arm is connected with the second bridge arm in series, and the third bridge arm is connected with the fourth bridge arm in series; a series branch formed by the first bridge arm and the second bridge arm and a series branch formed by the third bridge arm and the fourth bridge arm are connected in parallel to form the H-bridge circuit; the direct current reactor and the direct current resistor which are connected in parallel form a series circuit with the main circuit breaker, and two ends of the series circuit are respectively connected to a public connection point of the first bridge arm and the third bridge arm and a public connection point of the second bridge arm and the fourth bridge arm;
the main circuit breaker specifically comprises an IGBT string connected in parallel, a load branch formed by connecting a quick mechanical switch and a load switch in series and a lightning arrester; the direct current lines are respectively connected with the common connection points of the first bridge arm and the second bridge arm and the common connection points of the third bridge arm and the fourth bridge arm.
2. A dc fault current limiter for a self-clearing MMC dc distribution network as claimed in claim 1, wherein a certain number of said current limiters are configured at dc line terminals based on self-clearing MMC converter stations.
3. Method for controlling a dc fault with the use of a dc fault current limiter for self-clearing a dc fault current limiter of a MMC dc distribution network as claimed in any one of claims 1 to 2, characterized in that it comprises the following steps
Step 1, under a normal operation state, the first bridge arm and the fourth bridge arm are conducted, an IGBT string in a main circuit breaker is locked, a quick mechanical switch is closed, a load branch is conducted, and a direct-current line current idcFlows through the first bridge arm, the DC reactor, the load branch and the fourth bridge arm, and the current-limiting resistor is arranged by the DC reactorThe second bridge arm and the third bridge arm are turned off;
step 2, when the direct current fault is detected, the IGBT in the main circuit breaker is immediately conducted, a conducting signal is applied to the quick mechanical switch, and the IGBT in the load branch is locked, so that the fault current is converted from the load branch to the main circuit breaker, and the preparation is made for dissipating the fault energy; then, reverse polarity capacitance voltage is applied to a fault current circuit, fault current charges a capacitor, the fault current is rapidly attenuated, when the fault current is zero, the reverse clamping effect of a diode clamps the fault current to be zero, and rapid clearing of the fault current is realized;
step 3, after the fault point is in an isolated state, the continuous current of the direct current reactor generates reverse voltage, so that the second bridge arm and the fourth bridge arm are conducted, the continuous current generated by the direct current reactor only flows in the second bridge arm and the fourth bridge arm, and after the fault current is limited, the direct current reactor is bypassed from a fault circuit;
and 4, restoring the current limiter to supply power to the whole direct-current power distribution network: first turn off the IGBT, i of the main breakerLThe rapid decrease, the recovery process is as follows:
(1) when the main breaker IGBT is disconnected, when idc<iLAt/2, idcDirectly flows through a bridge arm III and a bridge arm IV;
(2)iLcontinuously decrease, idcRises rapidly when idc≥iLA/2 and iL/2<IdcNWhen the bridge arm three is not conducted, iLThe current can only flow through a second bridge arm and a fourth bridge arm; in this case, the influence of the recovery process of the current limiter on the dc system is still small;
(3) when i isL＝IdcNWhen the direct current fault current limiter is completely recovered, preparing for the next fault;
wherein, IdcNIs the rated current of the DC line iLIs the current flowing through the DC reactor, IdcIs the current flowing through the dc line.
CN202111144569.1A 2021-09-28 2021-09-28 Direct-current fault current limiter suitable for self-clearing MMC type direct-current distribution network and control method Pending CN113889984A (en)

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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20210226439A1 (en) * 2017-05-31 2021-07-22 Tianjin University Novel dc solid-state circuit breaker with self-adapt current limiting capability and the control method thereof
CN113162000A (en) * 2021-01-08 2021-07-23 天津大学 Improved self-adaptive current-limiting direct current solid-state circuit breaker and control method thereof

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20210226439A1 (en) * 2017-05-31 2021-07-22 Tianjin University Novel dc solid-state circuit breaker with self-adapt current limiting capability and the control method thereof
CN113162000A (en) * 2021-01-08 2021-07-23 天津大学 Improved self-adaptive current-limiting direct current solid-state circuit breaker and control method thereof

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
HUIJIELYU: "An improved Fault Current Limiter for self-clearing MMC-based dc distribution network", 《2021 IEEE 4TH INTERNATIONAL ELECTRICAL AND ENERGY CONFERENCE》 *

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