CN116316465A - Current-limiting circuit breaker suitable for direct current interconnection and fault clearing method thereof - Google Patents

Current-limiting circuit breaker suitable for direct current interconnection and fault clearing method thereof Download PDF

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Publication number
CN116316465A
CN116316465A CN202211618220.1A CN202211618220A CN116316465A CN 116316465 A CN116316465 A CN 116316465A CN 202211618220 A CN202211618220 A CN 202211618220A CN 116316465 A CN116316465 A CN 116316465A
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current
fault
limiting
branch
branch circuit
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CN202211618220.1A
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Inventor
庞丹
王泽一
王欣铎
于洪涛
王振浩
赵昌鹏
张�浩
王志鹏
王尉
许欣
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Changchun Power Supply Co Of State Grid Jilinsheng Electric Power Supply Co
Northeast Electric Power University
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Changchun Power Supply Co Of State Grid Jilinsheng Electric Power Supply Co
Northeast Dianli University
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Priority to CN202211618220.1A priority Critical patent/CN116316465A/en
Publication of CN116316465A publication Critical patent/CN116316465A/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
    • 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
    • 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
    • H02J3/001—Methods to deal with contingencies, e.g. abnormalities, faults or failures
    • 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

A current-limiting circuit breaker suitable for direct current interconnection and a fault clearing method thereof belong to the technical field of flexible direct current interconnection. The invention aims to quickly remove fault current on the direct current side of a converter station through matching of all branches in the topology of a current-limiting high-voltage direct current circuit breaker, and can inhibit the rising rate of the fault current and reduce the energy consumption requirement of a lightning arrester. The method comprises the following steps: and establishing the topology of the current-limiting high-voltage direct-current circuit breaker, and analyzing the fault clearing process of the topology of the current-limiting high-voltage direct-current circuit breaker. The invention has low steady-state loss and is suitable for high-voltage direct-current power grids; the fast isolation and slow energy consumption can be realized, and the fast isolation device is suitable for working conditions with some requirements on rapidity. In summary, the invention has the advantages of scientific method, strong applicability, good effect and the like.

Description

Current-limiting circuit breaker suitable for direct current interconnection and fault clearing method thereof
Technical Field
The invention belongs to the technical field of flexible direct current interconnection.
Background
The flexible direct current interconnection technology based on the modularized multi-level converter (modular multilevel converter, MMC) has the unique technical advantages of flexible control mode, no need of strong power grid support, capability of realizing multi-power supply, multi-drop point power reception and the like, and is rapidly developed. The direct current power grid based on the flexible direct current transmission technology is widely paid attention to because of high power supply reliability and low unit transmission cost. However, due to its grid interconnection nature, local faults are instead more likely to spread across the grid via the lines. Once the direct current line has a short circuit fault, an internal energy storage element of the converter station and a fault point form a discharge loop rapidly, so that fault current rapidly reaches the tolerance upper limit of power electronic devices within a few ms, and huge hidden trouble is caused to the operation of the converter station and a direct current power grid.
The direct current circuit breaker (DC circuit breaker, DCCB) is the most direct and effective scheme for processing direct current faults, and after the direct current faults occur, the fault lines are rapidly cut off by using the DCCB, so that the influence of the faults on a direct current power grid can be reduced to the greatest extent. The hybrid DCCB has the advantages of both the mechanical DCCB and the all-solid DCCB (small on-state loss and high on-off speed), and becomes one of the necessary devices for the dc power grid. Currently, ABB company has developed a hybrid DCCB with a rated voltage of 320kV, a rated current of 2.6kA, and capable of breaking a fault within 5ms, and is widely used in dc engineering. However, as the voltage level of the direct current power grid is improved, the rising speed of the fault current is faster, so that the DCCB bears higher transient voltage value and rising speed of the fault current in the fault current breaking process, and the energy consumption requirement of the lightning arrester is increased. Therefore, a new solution is needed to solve this problem.
Disclosure of Invention
The invention aims to quickly remove fault current on the direct current side of a converter station through matching of all branches in the topology of a current-limiting high-voltage direct current circuit breaker, and can inhibit the rising rate of the fault current and reduce the energy consumption requirement of a lightning arrester.
The method comprises the following steps:
s1, establishing topology of current-limiting type high-voltage direct-current circuit breaker
The current-limiting type high-voltage direct-current circuit breaker topology mainly comprises a steady-state branch circuit, a current-limiting branch circuit, an isolation branch circuit and an auxiliary branch circuit 4; the steady-state branch is formed by connecting an ultra-fast mechanical switch UFD and a load change-over switch in series;
the current-limiting branch consists of 1 pre-charge capacitor and 4 bridge arm branches: (1) main current limiting impedance R 1 、L 1 And thyristor valve group T 1 A branch circuit formed by series connection; (2) precharge capacitor C 1 A branch circuit formed separately; (3) thyristor valve group T 3 、T 4 A branch circuit is formed; (4) auxiliary current limiting resistor R 2 Thyristor valve group T 2 A branch circuit formed by connecting the diode valve group D in series and parallel;
the isolation branch is formed by connecting a unidirectional IGBT valve bank and a lightning arrester in parallel;
the auxiliary branch is formed by connecting 2 parts in parallel: (1) energy dissipation resistor R 3 And diode D 5 A branch circuit formed by series connection; (2) precharge capacitor C 2 Residual current switch and thyristor valve bank T 5 A branch circuit formed by serial-parallel connection;
s2, analyzing fault clearing process of current-limiting type high-voltage direct-current breaker topology
t 0 At the moment, the direct current line on the right side of the convertor station has short circuit fault, and the short circuit fault is short-circuitedAfter delay, t 1 When the system detects a fault, the current-limiting high-voltage direct-current circuit breaker immediately applies a turn-off signal to the steady-state branch circuit, and simultaneously rapidly transfers fault current through the current-limiting branch circuit and the isolation branch circuit;
t 2 after the UFD has a certain insulation capacity, the thyristor valve group T in the current-limiting branch circuit 1 ～T 4 To the precharge capacitor C 1 Charging and discharging are carried out, and finally at t 4 At the moment, the L of the current-limiting branch is 1 、R 1 、R 2 A fault discharge loop of the series-connected converter station;
from t 4 At the beginning of moment, the fault discharging loop of the converter station is connected in series with L 1 、R 1 、R 2 The impedance of the fault discharge loop is increased, and the amplitude and the rising rate of fault current are inhibited; t is t 5 At the moment, fault current is cut off through the lightning arrester in the isolation branch, and simultaneously, the capacitor C is precharged 2 The parallel connection is connected to a fault loop to provide certain back pressure and accelerate the fault isolation speed; t is t 6 At the moment, the fault current gradually drops to 0, the fault line is isolated, C 2 The voltage drops to 0 due to the fact that the stored energy is also completely transferred to the smoothing reactor; t is t 6 At the beginning of the moment, smoothing reactor L dc Energy part of (C) 2 Reverse charge, a part is R 3 Dissipating to t 7 Time C 2 End of reverse charging of C 2 The branch is turned off; t is t 7 Starting at the moment, R 3 Continue dissipating L dc T is the residual energy storage of 8 Time of day, R 3 And the energy consumption is ended.
The invention has the following beneficial effects: 1) The steady-state loss is low, and the method is suitable for a high-voltage direct-current power grid; 2) The current limiting branch is introduced, so that the rising speed and peak value of fault current are effectively restrained, and the technical requirement of breaking off the current by the circuit breaker is reduced; 3) The auxiliary branch is introduced, so that the smoothing reactor has the capability of actively extinguishing energy, fault isolation and smoothing energy consumption are decoupled, fast isolation and slow energy consumption can be realized, and the smoothing reactor is suitable for working conditions with some rapidity requirements. In summary, the invention has the advantages of scientific method, strong applicability, good effect and the like.
Drawings
FIG. 1 is a schematic diagram of the topology of a current-limited HVDC circuit breaker of the present invention;
FIG. 2 is a schematic diagram of a single-ended equivalent circuit of the current-limited HVDC circuit breaker topology of the present invention;
FIG. 3a shows a fault detection stage (t) 0 <t<t 1 ) A current flow path schematic;
FIG. 3b shows a current transfer stage (t) 1 <t<t 2 ) A current flow path schematic;
FIG. 3c shows a current limiting stage 1 (t) 2 <t<t 3 ) A current flow path schematic;
FIG. 3d shows a current limiting stage 2 (t) 3 <t<t 4 ) A current flow path schematic;
FIG. 3e shows a current limiting stage 3 (t) 4 <t<t 5 ) A current flow path schematic;
FIG. 3f shows a current breaking stage (t) 5 <t<t 6 ) A current flow path schematic;
FIG. 3g shows the energy consumption stage 1 (t) 6 <t<t 7 ) A current flow path schematic;
FIG. 3h shows the energy consumption stage 2 (t) 7 <t<t 8 ) A current flow path schematic;
FIG. 4a shows a precharge capacitor C according to the present invention 1 And fault current i d A relationship graph between the two;
FIG. 4b shows a precharge capacitor C of the present invention 1 And a voltage u C1 A relationship graph between the two;
FIG. 5 shows a main current limiting resistor R according to the present invention 1 Fault current i d A relationship graph between the two;
figure 6 is a main current limiting reactance L of the present invention 1 Fault current i d A relationship graph between the two;
FIG. 7 shows an auxiliary current limiting resistor according to the present inventionR 2 Fault current i d A relationship graph between the two;
FIG. 8 is a graph comparing fault current during fault clearing of the present invention with a conventional hybrid DCCB;
fig. 9 is a graph comparing the energy consumption of the lightning arrester during fault clearing of the present invention and the conventional hybrid DCCB;
fig. 10 is a diagram of a current limiting circuit breaker according to the present invention.
Detailed Description
The invention comprises the following steps, which are sequentially carried out:
step one, establishment of current-limiting type high-voltage direct-current breaker topology
The current-limiting type high-voltage direct-current circuit breaker topology mainly comprises a steady-state branch circuit, a current-limiting branch circuit, an isolation branch circuit and an auxiliary branch circuit 4. The steady-state branch is formed by connecting an ultra-fast mechanical switch UFD and a load transfer switch (load commutation switch, LCS) in series.
The current-limiting branch circuit consists of 1 pre-charge capacitor and 4 bridge arm branches: (1) main current limiting impedance R 1 、L 1 And thyristor valve group T 1 A branch circuit formed by series connection; (2) precharge capacitor C 1 A branch circuit formed separately; (3) thyristor valve group T 3 、T 4 A branch circuit is formed; (4) auxiliary current limiting resistor R 2 Thyristor valve group T 2 And a branch circuit formed by connecting the diode valve groups D in series and parallel.
The isolation branch is formed by connecting a one-way IGBT valve group and a lightning arrester in parallel.
The auxiliary branch is formed by connecting 2 parts in parallel: (1) energy dissipation resistor R 3 And diode D 5 A branch circuit formed by series connection; (2) precharge capacitor C 2 Residual current switch (residual current breaker, RCB), thyristor valve block T 5 And the branches are formed by serial-parallel connection.
Step two, analyzing fault clearing process of current-limiting type high-voltage direct-current breaker topology
t 0 At moment, the direct current line on the right side of the converter station has short circuit fault, and t is after short delay 1 The moment system detects the fault, the current-limiting type high-voltage direct-current breaker immediately stabilizesAnd the state branch circuit applies a turn-off signal, and simultaneously rapidly transfers fault current through the current-limiting branch circuit and the isolation branch circuit to ensure the reliable turn-off of the UFD.
t 2 After the UFD has a certain insulation capacity, the thyristor valve group T in the current-limiting branch circuit 1 ～T 4 To the precharge capacitor C 1 Charging and discharging are carried out, and finally at t 4 At the moment, the L of the current-limiting branch is 1 、R 1 、R 2 The fault discharge loops of the converter stations are connected in series.
From t 4 At the beginning of moment, the fault discharging loop of the converter station is connected in series with L 1 、R 1 、R 2 The impedance of the fault discharge loop is increased, and the amplitude and the rising rate of fault current are suppressed. t is t 5 At the moment, fault current is cut off through the lightning arrester in the isolation branch, and simultaneously, the capacitor C is precharged 2 The parallel connection is connected to the fault loop to provide a certain back pressure and accelerate the fault isolation speed. t is t 6 At the moment, the fault current gradually drops to 0, the fault line is isolated, C 2 The voltage drops to 0 as the stored energy is also transferred entirely to the smoothing reactor.
t 6 At the beginning of the moment, smoothing reactor L dc Energy part of (C) 2 Reverse charge, a part is R 3 Dissipating to t 7 Time C 2 End of reverse charging of C 2 The branch is turned off. t is t 7 Starting at the moment, R 3 Continue dissipating L dc T is the residual energy storage of 8 Time of day, R 3 And the energy consumption is ended. Above t 0 ～t 8 The whole process of the method is the fault clearing process of the current-limiting type high-voltage direct-current breaker.
The invention is described in further detail below with reference to the attached drawing figures:
the fault clearing method based on the current limiting type high-voltage direct current breaker topology comprises the following steps, as shown in fig. 1 to 7, and the following steps are sequentially carried out:
step one, establishing a current-limiting type high-voltage direct-current breaker topology: the current-limiting type high-voltage direct-current circuit breaker topology takes a bridge circuit formed by diodes as a main structure, so that the current-limiting type high-voltage direct-current circuit breaker topology has bidirectional current limiting capability and bidirectional fault clearing capability.
The steady-state branch consisting of ultra-fast mechanical switch UFD and LCS in series is used for low-loss through-flow when the system is in steady-state operation, and transient overvoltage after the LCS is turned off is mainly borne by the UFD, so that the LCS can meet the requirement only by a small number of IGBTs in series.
In the current-limiting branch, the current is limited by a main current-limiting impedance R 1 、L 1 And thyristor valve group T 1 The bridge arm branches formed in series are used for inhibiting the rising rate of fault current, reducing the peak value of the fault current and inhibiting the current in the pre-charging stage, so that the impact of excessive charging current on a flexible direct current grid is avoided; by precharging a capacitor C in a current-limiting branch 1 Can control the current flowing on 4 bridge arms of the current-limiting branch circuit to finally ensure L 1 And R is 1 The series connection is connected into a fault discharging loop; the current-limiting branch is added with a valve group T of only thyristors 3 、T 4 The formed bridge arm branch circuit has the function of rapidly transferring fault current and ensuring the turn-off of the UFD under the working condition of zero current; an auxiliary current-limiting resistor R is also added in the current-limiting branch 2 And thyristor valve group T 2 Bridge arm branch circuit formed by parallel-serial connection of diode valve group D and R 2 Either through T 2 Is connected in series in the fault discharging loop, and the action of the fault discharging loop is as follows 1 Similarly, also through T 2 Series connection C 1 Is to suppress C 1 Is provided. After the fault is isolated, R 2 Can pass through D 5 、T 4 And C 1 Form an energy consumption loop, C 1 Is dissipated, and is used for preparing reclosing.
The isolation branch is formed by connecting the unidirectional IGBT valve bank and the lightning arrester in parallel, and the lightning arrester can be connected into a loop only by locking the IGBT, so that the rapid isolation of faults is realized.
The auxiliary branch comprises two core devices: energy dissipation resistor R 3 And a precharge capacitor C 2 . Energy dissipation resistor R 3 The method is mainly used for absorbing the energy of the smoothing reactor after fault isolation; precharge capacitor C 2 Can be connected with a pre-charge capacitor C 1 Forming a charging loop without external assistanceC can be completed by the power supply 1 And precharge capacitor C 2 Can pass T in the process of isolating branch to break current 5 The parallel connection is connected into a fault loop to provide certain back pressure and shorten the time required by fault isolation.
Analyzing fault clearing process of the current-limiting type high-voltage direct-current breaker topology: t is t 0 At moment, the direct current line on the right side of the converter station has short circuit fault, and t is after short delay 1 The time control and protection system detects a fault and sends a state transition action instruction to the current-limiting high-voltage direct-current breaker, and immediately sends a turn-off signal to the UFD and the LCS of the steady-state branch after receiving the action instruction, and simultaneously turns on the IGBT of the isolation branch and sends a turn-off signal to the T of the current-limiting branch 3 、T 4 A trigger pulse is applied. The IGBTs of the LCS are turned off immediately, and the fault current is quickly transferred to T 3 、T 4 The branch is located. After a short mechanical breaking delay (2 ms), t 2 At the moment, the UFD reaches the nominal opening distance. .
t 2 At any time, UFD has a certain insulation capacity and is directed to T of current-limiting branch 2 Applying trigger pulses while continuously triggering T 1 Ensure T 1 Conducting at the first time of being subjected to a forward voltage drop. At T 2 Trigger instant, C 1 Immediately form a discharge loop with the fault point, T 3 The current of the branch circuit is immediately transferred to T 2 Branch, at the same time T 3 Will bear C 1 Is turned off by the reverse pressure drop of (a). t is t 3 Time C 1 After the discharge is completed, the energy storage element in the converter station continuously moves to C 1 Reverse charging, T 1 Will be at C 1 The first time of capacitor voltage reversal is conducted by bearing forward voltage drop; with C 1 Rise of reverse voltage, T 4 The branch current gradually decreases until t 4 Time, T 4 The branch current is reduced to 0, C 1 The branch is disconnected.
From t 4 Starting at the moment, limiting the L of the branch 1 、R 1 、R 2 Fault discharge loop of series-connected converter station, increasing impedance of fault discharge loop, and inhibiting amplitude and failure currentRate of rise. t is t 5 At moment, the IGBT of the isolation branch is turned off, the lightning arrester is connected into a fault loop to start cutting off fault current, and meanwhile, the thyristor valve bank T in the auxiliary branch is triggered 5 ，C 2 And the stored energy of (c) starts to be transferred to the smoothing reactor. t is t 6 At the moment, the fault current gradually drops to 0, the fault line is isolated, C 2 All the stored energy is transferred to the smoothing reactor until the direct current fault is isolated.
From t 6 Starting at the moment, the fault energy consumption process is adopted. t is t 6 Time C 2 The voltage is reduced to 0 due to the total transfer of energy, followed by smoothing reactor L dc Start to C 2 Reverse charging until t 7 Time C 2 Is charged in the reverse direction, T 5 At C 2 The branch current is turned off when falling to 0, C 2 Maintaining a certain back pressure. At t 6 ～t 7 Within a period of time D 5 Is conducted due to back pressure, R 3 Start dissipating L dc Is used for storing energy. t is t 7 Starting at the moment, R 3 And L is equal to dc Form a series circuit to continue dissipating L dc Up to t 8 Time L dc The remaining energy storage of (c) is dissipated and the dc fault is cleared.
The current limiting branch circuit is a core branch circuit of a current limiting circuit breaker topology, parameters of elements in the current limiting branch circuit directly influence the current limiting effect of the current limiting circuit breaker topology, and further influence the fault current amplitude born by the circuit breaker and the energy absorbed by the lightning arrester in the fault clearing process, so that the parameters of the elements in the current limiting branch circuit should be optimally designed.
Precharge capacitor C in the present invention 1 Is selected from: as can be seen from FIG. 4, C 1 The smaller the value of (C), the lower the amplitude of the fault current, the better the current limiting effect, but at the same time C 1 The greater the back pressure experienced, the greater the number of capacitors needed, C 1 The selection of (2) should be made by comprehensively considering the current limiting effect and the number of required devices.
The precharge capacitor R in the invention 1 Is selected from: as can be seen from fig. 5, the main current limiting resistor R 1 The larger the flow limiting effect is, the better. But is electrically connected toThe resistance volume and the heat dissipation requirement are proportional to the resistance value, and the main current-limiting resistor R 1 The selection of (2) should be taken into consideration comprehensively the heat dissipation, economy and current limiting effect.
The main current limiting reactance L in the invention 1 Is selected from: see fig. 6, main current limiting reactance L 1 The larger the value of (2), the slower the secondary rise rate of the fault current, the more the technical requirements for the manufacture of the circuit breaker can be reduced, but the higher the corresponding engineering cost will be, and the greater the challenges to the insulation and safety problems thereof will be faced, so that the primary current limiting reactance L 1 Should be carefully selected in consideration of the above factors.
Auxiliary current limiting resistor R in the invention 2 Is selected from: see fig. 7, auxiliary current limiting resistor R 2 The greater the resistance, the better the current limiting effect, but when the magnitude (R 2 =12Ω) no longer satisfies T 3 Branch circuit is switched to T 2 When the constraint condition of the branch circuit is met, the current limiting branch circuit fails to switch, and the current limiting circuit breaker does not have the current limiting function any more, and the effect of the current limiting circuit breaker is equal to that of the traditional mixed DCCB. Thus auxiliary current limiting resistor R 2 The selection of (1) should first consider the constraint condition of the switching path and then consider the current limiting effect.
Simulation analysis: based on PSCAD electromagnetic simulation software, a simulation model of the four-terminal direct current power grid shown in figure 10 is built. The dc grid parameters are shown in table 1.
Table 1 dc grid parameters
Figure SMS_1
In order to verify the superiority of the fault clearing method of the current-limiting type high-voltage direct-current breaker topology, the fault clearing method is compared and analyzed with the fault clearing method of the traditional mixed DCCB. Scheme 1 is a fault clearing method of a traditional hybrid DCCB, and scheme 2 is a fault clearing method of a current-limiting type high-voltage direct-current breaker topology. In a current-limited high-voltage direct-current circuit breaker topology: main current-limiting resistor R 1 Take 10Ω, main current limiting reactance L 1 Taking 15mH and assisting in limiting current R 2 Taking 5 omega, pre-charging capacitor C 1 10uF was taken.
When the Line34 with the largest rated current has short circuit fault in 2.0s, the fault detection time is 1ms, the time required for the UFD to reach the rated opening distance is 2ms, and after the fault occurs for 5.5ms, the lightning arrester starts to cut off the fault current. A simulated comparison of the two schemes is shown in fig. 8 and 9.
As can be seen from fig. 8 and fig. 9, the scheme 1 does not have the capability of suppressing the fault current, the fault current is always and rapidly increased with the same slope, after 5.5ms of fault occurs, the lightning arrester is connected into the fault loop, and the fault current begins to be cut off, because the current amplitude is higher at the moment of breaking the fault current, fault isolation is realized only 6.5ms after the fault occurs, and the lightning arrester absorbs more energy; scheme 2 the fault current secondary rise rate is significantly reduced after the current limiting impedance is fully put into service. Compared with scheme 1, the peak value of the fault line current is reduced by 19.2%, the amplitude of the fault current is reduced by 58.8% at the moment of breaking the current, the rising rate and the peak value of the fault current are obviously reduced, and the scheme II completes fault isolation 5.85ms after the fault occurs, and compared with the scheme I, the time required by fault isolation is shortened by 10%. And because the auxiliary branch is introduced, the flat wave quenching energy is not dependent on the lightning arrester any more, and the fault current amplitude is lower at the moment of breaking the current, and the absorption energy of the lightning arrester in the scheme II is reduced by 66.8 percent compared with that in the scheme 1.
Table 2 comparison of the performance of the two schemes
Figure SMS_2
The overall performance of the two schemes is shown as 2, and the fault clearing method of the current-limiting high-voltage direct-current breaker topology provided by the invention has obvious advantages compared with the fault clearing method of the existing hybrid DCCB, and has stronger applicability in a direct-current power grid.

Claims (1)

1. A current-limiting circuit breaker suitable for direct current interconnection and a fault clearing method thereof are characterized in that: the method comprises the following steps:
s1, establishing topology of current-limiting type high-voltage direct-current circuit breaker
The current-limiting type high-voltage direct-current circuit breaker topology mainly comprises a steady-state branch circuit, a current-limiting branch circuit, an isolation branch circuit and an auxiliary branch circuit 4;
the steady-state branch is formed by connecting an ultra-fast mechanical switch UFD and a load change-over switch in series;
the current-limiting branch consists of 1 pre-charge capacitor and 4 bridge arm branches: (1) main current limiting impedance R 1 、L 1 And thyristor valve group T 1 A branch circuit formed by series connection; (2) precharge capacitor C 1 A branch circuit formed separately; (3) thyristor valve group T 3 、T 4 A branch circuit is formed; (4) auxiliary current limiting resistor R 2 Thyristor valve group T 2 A branch circuit formed by connecting the diode valve group D in series and parallel;
the isolation branch is formed by connecting a unidirectional IGBT valve bank and a lightning arrester in parallel;
the auxiliary branch is formed by connecting 2 parts in parallel: (1) energy dissipation resistor R 3 And diode D 5 A branch circuit formed by series connection; (2) precharge capacitor C 2 Residual current switch and thyristor valve bank T 5 A branch circuit formed by serial-parallel connection;
s2, analyzing fault clearing process of current-limiting type high-voltage direct-current breaker topology
t 0 At moment, the direct current line on the right side of the converter station has short circuit fault, and t is after short delay 1 When the system detects a fault, the current-limiting high-voltage direct-current circuit breaker immediately applies a turn-off signal to the steady-state branch circuit, and simultaneously rapidly transfers fault current through the current-limiting branch circuit and the isolation branch circuit;
t 2 after the UFD has a certain insulation capacity, the thyristor valve group T in the current-limiting branch circuit 1 ～T 4 To the precharge capacitor C 1 Charging and discharging are carried out, and finally at t 4 At the moment, the L of the current-limiting branch is 1 、R 1 、R 2 A fault discharge loop of the series-connected converter station;
from t 4 At the beginning of moment, the fault discharging loop of the converter station is connected in series with L 1 、R 1 、R 2 The impedance of the fault discharge loop is increased, and the amplitude and the upper part of fault current are restrainedRate of rise; t is t 5 At the moment, fault current is cut off through the lightning arrester in the isolation branch, and simultaneously, the capacitor C is precharged 2 The parallel connection is connected to a fault loop to provide certain back pressure and accelerate the fault isolation speed; t is t 6 At the moment, the fault current gradually drops to 0, the fault line is isolated, C 2 The voltage drops to 0 due to the fact that the stored energy is also completely transferred to the smoothing reactor; t is t 6 At the beginning of the moment, smoothing reactor L dc Energy part of (C) 2 Reverse charge, a part is R 3 Dissipating to t 7 Time C 2 End of reverse charging of C 2 The branch is turned off; t is t 7 Starting at the moment, R 3 Continue dissipating L dc T is the residual energy storage of 8 Time of day, R 3 And the energy consumption is ended.
CN202211618220.1A 2022-12-15 2022-12-15 Current-limiting circuit breaker suitable for direct current interconnection and fault clearing method thereof Pending CN116316465A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117013510A (en) * 2023-09-27 2023-11-07 国网江苏省电力有限公司电力科学研究院 Superconductive current-limiting hybrid direct current breaker for controllable energy dissipation

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117013510A (en) * 2023-09-27 2023-11-07 国网江苏省电力有限公司电力科学研究院 Superconductive current-limiting hybrid direct current breaker for controllable energy dissipation

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