A kind of current-limiting type high-speed reclosure direct-current breaker topology structure and control method
Technical field
The present invention relates to Power System Flexible direct current transportation fields, are quickly overlapped in particular to a kind of current-limiting type
Lock direct-current breaker topology structure and control method.
Background technique
In recent years, flexible DC transmission technology rapidly develop, as guarantee its safe and stable operation dc circuit breaker with
Become research hotspot.Compared with regular alternating current power grid, flexible direct current power grid lacks natural zero-crossing point, and power grid damps low, failure
Electric current rises comparatively fast, and smoothing reactor is larger, the energy that need to release is higher, these three features propose dc circuit breaker can
By cutout, quick acting, effective requirement for letting out three aspect such as energy.
Current dc circuit breaker is often divided into three classes scheme according to technical principle: mechanical, solid state and hybrid straight
Flow breaker.Wherein hybrid dc circuit breaker is integrated with the advantages of low mechanical on-state loss and solid state quick action,
It is the scheme most potential in high-voltage large-capacity occasion.Most of hybrid dc circuit breakers are all by main branch, transfer branch, consumption
It can three branches compositions of branch.Main branch is in series by Fast mechanical switch and assist exchanging circuit submodule, when to operate normally
Through-flow branch;Transfer branch routes a large amount of power electronic devices and constitutes in series and parallel, is the core for realizing circuit breaker failure turn-off capacity
Center portion point;The branch that consumes energy routing arrester composition, for absorbing the energy and inhibit disjunction that inductive element stores in direct current system
Voltage.
There are still some problems to be solved, two problems more outstanding, first is that DC grid event for hybrid scheme
It is too fast to hinder electric current rising, excessive demand is proposed to fault detection means and Fast mechanical switch;Second is that dc circuit breaker needs
Using a large amount of power electronic devices, higher cost.Therefore, existing improvement project mostly surrounds both of these problems, limits in failure
Stream proposes New Measure with drop low cost aspect.
The prior art by it is normal through-flow when inductance in parallel, failure when the concatenated mode of inductance, effectively realize current limliting effect
Fruit, but more extras are added in it, increase cost and control is complex.
The prior art takes the structure that two sets of through-flow branches add a set of transfer branch, so that IGBT quantity and cost reduce
Half;And current-limiting inductance is divided into two parts by it, is grounded by dc circuit breaker so that two sides inductance forms different let out
Road is put back to, the energy for accelerating non-faulting side is released.Its there are the shortcomings that have: two sets of through-flow branches still increase Quick mechanical and open
Close the cost with auxiliary converter circuit;The energy of failure side inductance is released more slowly, and reclosing effect is affected;Direct current interruption
After device is directly grounded so that shifting branch conducting, failure side inductance can not play metering function.
In conclusion hybrid dc circuit breaker remains some disadvantages urgently in current limliting and in terms of reducing cost two
It improves.
Summary of the invention
To solve the above-mentioned problems, the invention proposes a kind of current-limiting type high-speed reclosure direct-current breaker topology structure and
Control method can effectively solve two sets of through-flow high cost problems of branch bring, fault current limiting climbing and peak value, and big
The energy that width accelerates failure side inductance is released speed, and high-speed reclosure is conducive to.
To achieve the goals above, the present invention adopts the following technical scheme:
A kind of current-limiting type high-speed reclosure direct-current breaker topology structure disclosed in one or more embodiments, packet
It includes: current-carrying circuit, current-limiting circuit, converter circuit, cut-off circuit and freewheeling circuit;
The current-carrying circuit includes the mechanical switch being sequentially connected in series and assist exchanging circuit switch;The current-limiting circuit series connection
In current-carrying circuit two sides, the converter circuit is connected in parallel with current-carrying circuit, and the converter circuit includes two diode compositions
Upper bridge arm and lower bridge arm, the cut-off circuit be connected between upper and lower bridge arm, the freewheeling circuit is connected on converter circuit
Between lower bridge arm and the earth;
The cut-off circuit includes the power electronics branch and arrester branch that composition is connected in series in several submodules;It is described
Arrester branch and power electronics branch circuit parallel connection.
Further, the mechanical switch includes that multiple vacuum high-speed switches based on electromagnetic repulsion mechanism are connected in series,
The assist exchanging circuit switch includes two groups of power electronic devices differential concatenation connections, and each group includes at least one concatenated full control
Type electronic power switch.
Further, the converter circuit is diode bridge converter circuit, i.e., left and right ends respectively connect a upper bridge arm
With lower bridge arm, two upper bridge arms are crossed to form bridge arm intersection point, and two lower bridge arms are crossed to form lower bridge arm intersection point;Each bridge arm by
Several diode series aiding connection compositions, the anode of upper bridge arm diode are connect with the left and right two-end-point of converter circuit, two pole of lower bridge arm
The anode of pipe is connect with lower bridge arm intersection point;Series damped electricity is distinguished between the left and right endpoint of converter circuit and lower bridge arm diode
Resistance.
Further, the cut-off circuit is connected between the upper bridge arm intersection point of converter circuit and lower bridge arm intersection point, described
Cut-off circuit includes the power electronics branch and arrester branch that composition is connected in series in several submodules;The arrester branch with
Power electronics branch circuit parallel connection.
Further, each submodule includes an all-controlling power electronics device and the RCD in parallel with the device
Buffer circuit, wherein the resistance R in RCD buffer circuit and capacitor C series connection, diode D are connected in parallel on the two sides resistance R.
A kind of control method of current-limiting type high-speed reclosure dc circuit breaker disclosed in one or more embodiments,
Including failure breaking course, specifically:
After ground fault occurs, after the electric current on current-carrying circuit is greater than set threshold value, protective device issues action signal,
Assist exchanging circuit in current-carrying circuit, which switchs, to be disconnected, while cut-off circuit is connected;
Electric current is shifted to converter circuit and cut-off circuit;
After electric current is completely transferred to converter circuit and cut-off circuit, the mechanical switch into current-carrying circuit issues locking letter
Number;
After mechanical switch is fully disconnected, the power electronics branch in cut-off circuit, the conducting of arrester branch are turned off;
Non-faulting side inductance energy is released through arrester branch;Failure side inductance energy is released through converter circuit;
Energy, which is released, finishes i.e. declaration breaker disjunction completion.
A kind of control method of current-limiting type high-speed reclosure dc circuit breaker disclosed in one or more embodiments,
Including reclosing process, specifically:
It is delayed after breaker disjunction by setting, issues reclosing order, the power electronics branch being closed in cut-off circuit
Road;
The electrical quantity for detecting faulty circuit at this time, judges whether failure is removed;
If failure still has, power electronics branch is turned off, declares unsuccessful reclosing;
If failure is removed, it is closed the mechanical switch of current-carrying branch, the assist exchanging circuit for being then closed current-carrying branch is opened
It closes;
Electric current can be transferred to current-carrying branch, and the power electronics branch of cut-off circuit is turned off after the change of current, and electric current restores
To the normal condition for the current-carrying circuit that only circulates, declaration reclosing is smoothly completed.
Further, the setting delay time before reclosing is depending on specific power grid characteristic, generally several hundred milliseconds.
Further, the electrical quantity for detecting faulty circuit at this time, judges whether failure is removed, specifically: when reclosing
Faulty circuit electrical quantity, including fault current climbing or failure lateral circuit voltage are detected, the faulty circuit that will test is passed through
Electrical quantity judges whether failure still has compared with given threshold.
Compared with prior art, the beneficial effects of the present invention are:
1. inductance, which is divided into equal-sized two parts, is connected on breaker both ends;So when cutting off short trouble, both
Can both ends inductance play a role the fault current limiting rate of climb simultaneously, while arrester need to only release the energy of non-faulting side inductance
Amount makes release energy, time and the requirement of releasing of arrester all there was only original half;
2. breaker is grounded through freewheeling diode;Freewheeling diode makes fault current not flow directly into the earth, but passes through
Failure side inductance flows to ground fault again, so that failure side inductance still plays metering function before cut-off circuit shutdown, continues
Another effect for flowing diode is that failure side inductance is facilitated to put through fault point, the earth, freewheeling diode, damping resistance formation
Electrical circuit, energy of thus quickly releasing.
3. damping resistance R is added in bridge convertor circuit;Its bring three aspect the utility model has the advantages that
1. the rate of climb of the fault current on transfer branch road can be slowed down, the peak value of fault current is reduced, current limliting is played
Effect, and then reduce to the resistance to flowing pressure of device, extend service using life;
2. inductance energy is released in failure side, as damping resistance, plays the role of accelerating aerial drainage, thus greatly speed up
Failure side electric current falls to 0 speed, alleviates the continuous to failure lateral circuit, facilitate reclosing it is smooth into
Row.
3. the power electronics branch in cut-off circuit is closed when reclosing first, if failure there are still incite somebody to action on quickly by electric current
It rises, brings secondary pulse to system, and the addition of damping resistance will reduce fault current peak value, limit electric current rapid increase,
The impact of system is brought when coinciding with failure to reduce.
Detailed description of the invention
The accompanying drawings constituting a part of this application is used to provide further understanding of the present application, and the application's shows
Meaning property embodiment and its explanation are not constituted an undue limitation on the present application for explaining the application.
Fig. 1 is the topological structure schematic diagram of dc circuit breaker proposed by the present invention;
Fig. 2 is the dc circuit breaker action timing diagram indicated with time shaft;
Fig. 3 is the current path figure in each stage in dc circuit breaker action process;
Fig. 4 is the change of current wave simulation figure for embodying dc circuit breaker current-limiting inductance segmenting function;
Fig. 5 is the change of current wave simulation figure for embodying dc circuit breaker and freewheeling diode effect being added;
Fig. 6 is the inductive discharge wave simulation figure for embodying dc circuit breaker and damping resistance effect being added;
Fig. 7 is the change of current wave simulation figure for embodying dc circuit breaker and damping resistance effect being added;
Fig. 8 is the reclosing current waveform analogous diagram for embodying dc circuit breaker and damping resistance effect being added.
Specific embodiment
It is noted that following detailed description is all illustrative, it is intended to provide further instruction to the application.Unless another
It indicates, all technical and scientific terms that the present invention uses have logical with the application person of an ordinary skill in the technical field
The identical meanings understood.
It should be noted that term used herein above is merely to describe specific embodiment, and be not intended to restricted root
According to the illustrative embodiments of the application.As used herein, unless the context clearly indicates otherwise, otherwise singular
Also it is intended to include plural form, additionally, it should be understood that, when in the present specification using term "comprising" and/or " packet
Include " when, indicate existing characteristics, step, operation, device, component and/or their combination.
Embodiment one
Fig. 1 is the topology diagram of current-limiting type high-speed reclosure dc circuit breaker proposed by the present invention, comprising: including following
Five parts:
1. current-carrying circuit;It is made of Fast mechanical switch and assist exchanging circuit switch;
2. current-limiting circuit;Including two sections of equal-sized inductance, it is connected on current-carrying circuit two sides respectively;
3. converter circuit;Also known as diode bridge converter circuit, is in parallel with current-carrying circuit, including four diode bridges
Arm and two damping resistances;
4. cut-off circuit;It is connected between the upper and lower bridge arm of converter circuit, including power electronics branch and arrester branch;
5. freewheeling circuit;It is connected between the lower bridge arm and the earth of change of current branch, also known as freewheeling diode group, by multiple two
Pole pipe series aiding connection composition, anode are connected with the earth.
Wherein, current-carrying circuit includes FMS (Fast mechanical switch) and assist exchanging circuit switch, and the latter is by differential concatenation IGBT
(G1、G2) and its anti-paralleled diode group composition;Current-limiting circuit includes L1、L2Two equal-sized inductance;Diode bridge is changed
Current circuit is by diode bridge arm D1—D4, damping resistance R1With R2Composition;Cut-off circuit is by power electronics branch and arrester branch
Composition, the former is made of a large amount of submodules (SM) cascade, and each submodule includes IGBT and RCD buffer circuit, and wherein RCD is buffered
Resistance R and capacitor C series connection, diode D in circuit are connected in parallel on the two sides resistance R;The latter is gone here and there by several Zinc-Oxide Arresters (MOV)
Connection is constituted;Freewheeling circuit is by diode group D5It constitutes.It should be pointed out that this figure is to indicate convenient, replaced into individual devices
Group device, actually D1—D5、G1、G2, MOV can configure in groups in order to meet actual electric network demand.
Embodiment two
Dc circuit breaker disclosed in embodiment one is placed in single-end DC transmission line of electricity and is studied, it is assumed that dc circuit breaker is right
Ground fault occurs for side, then L1For non-faulting side inductance, L2For failure side inductance.Fig. 2 is the specific timing diagram of breaker actuation,
In conjunction with Fig. 2, the specific action sequence for describing failure disjunction is as follows:
T=t0When, ground fault occurs for dc circuit breaker right side circuit;
T=t1When, protective device detects failure, and breaker receives action signal;Dc circuit breaker disjunction carries
The assist exchanging circuit switch of current circuit, the power electronics branch for being closed at cutout branch, are embodied in locking G1, be connected all
IGBT in SM;Electric current by current-carrying circuit gradually the change of current to converter circuit, cut-off circuit.
T=t2When, the first time change of current is completed, and cut-off signals occur to Fast mechanical switch;
T=t3When, mechanical switch fully opens, disjunction power electronics branch, that is, the IGBT being latched in all SM;Electric current turns
The RCD buffer circuit in SM is moved to, capacitance voltage gradually rises;
T=t4When, capacitance voltage reaches arrester conduction threshold and is allowed to be connected, and electric current is completely transferred to arrester branch,
Arrester starts aerial drainage;Inductance L1Energy is released through arrester, inductance L2Energy is through fault point, the earth, D5And R2It releases.
T=t5When, non-faulting side inductance L1Energy release and finish through arrester, flow through the electric current drop of non-faulting lateral circuit
It is 0.
T=t5' when, failure side inductance L2Energy release and finish, the electric current for flowing through failure lateral circuit is reduced to 0.
Fig. 3 is the current path figure in each stage in dc circuit breaker action process;Changing for electric current is clearly visible from figure
Stream situation and energy are released the stage arrester aerial drainage circuit different with failure side inductance.
In order to better illustrate the present invention the characteristics of and beneficial effect, are specifically described in conjunction with simulation means.
Fig. 4 is breaker proposed by the present invention in failure disjunction, and segmentation is respectively adopted and is not segmented (L1、L2L is merged into,
It is placed on non-faulting side) change of current waveform in the case of current-limiting inductance.As can be seen that current-limiting inductance segmentation is so that arrester only needs to release
L1Energy, thus arrester electric current release the time reduce half.
Fig. 5 is breaker proposed by the present invention in failure disjunction, respectively through sustained diode5It is grounded and is directly grounded
In the case of change of current waveform.As can be seen that if be directly grounded, electric current when flowing through power electronics branch, fault current only by
To L1Current limliting, thus the rate of climb is faster, current peak is higher, and current limitation effect halves, and through sustained diode5Ground connection then can be with
Avoid such case.
Fig. 6 is breaker proposed by the present invention in failure disjunction, does not use damping resistance respectively, damps electricity using 10 Ω
It hinders and using the inductive discharge waveform in the case of three kinds of 20 Ω damping resistance.As can be seen that the addition of damping resistance passes through
L1Fault current rise that slower, peak value is lower, the time of releasing is shorter, pass through L2Fault current speed of releasing obviously mention
It rises, and the above effect increases with damping resistance and enhanced.
Fig. 7 is breaker proposed by the present invention in failure disjunction, does not use damping resistance respectively, damps electricity using 10 Ω
It hinders and using the change of current waveform in the case of three kinds of 20 Ω damping resistance.As can be seen that the addition of damping resistance is so that fault current
When flowing through power electronics branch, the rate of climb is slower, peak value is lower, so that the final time of releasing is shorter, and the above effect with
Damping resistance increases and enhances.
Embodiment three: reclosing
Operation timing of the breaker proposed by the invention in reclosing is told about in conjunction with Fig. 2:
Assuming that failure is in t=t5When successfully cut off, after of short duration delay, start reclosing;
T=t6When, it is closed power electronics branch, that is, the IGBT in all SM is connected;Electric current will rise again
T=t7When, detect faulty circuit electrical quantity with judge failure whether there are still;Such as detection current-rising-rate di/
Dt, it is assumed that it is more than preset threshold, and illustrating failure, there are still the IGBT being then latched in all SM, reclosing is counted out;If its
Lower than preset threshold, illustrates that failure is removed, then Continuity signal occurs to Fast mechanical switch, carry out following step;
T=t8When, Fast mechanical switch completes closure, then is closed assist exchanging circuit switch, i.e., to G1Send Continuity signal;It carries
Flowing branch will be connected, and electric current will be shifted to current-carrying circuit;
T=t9When, electric current is completely transferred to current-carrying circuit, and the IGBT being latched in all SM, reclosing smoothly completes.
In order to illustrate damping resistance is added for the beneficial effect of reclosing, it is illustrated in conjunction with emulation:
Fig. 8 be breaker proposed by the present invention in reclosing when failure, do not use respectively damping resistance, using 10 Ω hinder
Current simulations waveform in the case of buffer resistance and three kinds of 20 Ω damping resistance of use.Since failure still has, if being added without resistance
Rapid increase is brought larger stress to device, also brings overcurrent to system by buffer resistance, power electronics branch electric current after closure
Impact;As can be seen that the fault current that the addition of damping resistance passes through power electronic devices rises, slower, peak value is lower,
To alleviate the impact that reclosing brings device and system when failure, and this beneficial effect increases with damping resistance and is increased
By force.
It should be noted that this dc circuit breaker is two-way disjunction structure, the failure for generation in two sides has symmetrical junction
Structure is handled, thus if failure occurs on the left of dc circuit breaker, emulation conclusion described above is still set up.
Above-mentioned, although the foregoing specific embodiments of the present invention is described with reference to the accompanying drawings, not protects model to the present invention
The limitation enclosed, those skilled in the art should understand that, based on the technical solutions of the present invention, those skilled in the art are not
Need to make the creative labor the various modifications or changes that can be made still within protection scope of the present invention.