CN204089761U

CN204089761U - A kind of switching circuit for capacitor switching

Info

Publication number: CN204089761U
Application number: CN201420595821.XU
Authority: CN
Inventors: 不公告发明人
Original assignee: NANJING NUOLIAN DISTRIBUTION TECHNOLOGY Co Ltd
Current assignee: NANJING NUOLIAN DISTRIBUTION TECHNOLOGY Co Ltd
Priority date: 2014-10-15
Filing date: 2014-10-15
Publication date: 2015-01-07
Anticipated expiration: 2024-10-15

Abstract

The utility model for capacitor shoving in switching process, bounce, arcing, the problem such as to restrike, a kind of novel switching circuit for capacitor switching is proposed.Disclosed switching circuit is made up of road one-way conduction parts and a road controllable type mechanical switch Components Parallel Connection, take full advantage of the loss-free feature of mechanical switch, make use of one-way conduction parts to realize capacitor precharge to reach capacitor residual voltage be line voltage peak value simultaneously, control switch drops at the peak point of line voltage, effectively reduce the capacitor inrush phenomenon that voltage jump when capacitor drops into causes, eliminate the action response delayed impact of mechanical switch simultaneously, technology disclosed in the utility model achieves capacitor switching process no-flashy-flow, without arcing, after capacitor puts into operation, switching circuitry is lossless.

Description

A kind of switching circuit for capacitor switching

Technical field

The utility model relates to Automatization in Power Distribution Network field, particularly relates to a kind of switching circuit for capacitor switching.

Background technology

In electric power system, capacitor is widely used for carrying out reactive power compensation, the adjustment application scenario such as voltage, harmonic inhabitation to electrical network, is one of visual plant of Automatization in Power Distribution Network.

When capacitor drops into electrical network, due to the intrinsic propesties of capacitor, it is when dropping into electrical network, can produce and shove, the capacitor when size that capacitor shoves when dropping into drops into capacitor is relevant with the voltage difference between power supply, sometimes shoving can rated capacitor size of current more than more than hundred times, and so huge shoving can have a huge impact the life-span of capacitor, produce severe jamming to electrical network, also may damage the fling-cut switch parts of capacitor simultaneously.

When capacitor exits electrical network, because capacitor accesses electrical network, there is corresponding capacitor electrode to flow through in capacitor switching switch block, now the fling-cut switch of capacitor is proposed to breaking current, eliminates the requirement of flashing, arcing, to ensure that capacitor can correctly disjunction.

The modes such as A.C. contactor, thyristor switch, combination switch and phase-selecting switch are mainly contained at present at the fling-cut switch of capacitor.

A.C. contactor is pure mechanical part, there is not optimum operation phase point in theory, switching instantaneous point can not be selected, when dropping into or excise electrical network, because its switching phase point is random, the surge current that amplitude is very large, frequency is very high can be produced during input, when exiting, easily produce electric arc, scaling loss contact.

Thyristor switch take controllable silicon as the switching parts of core along with the development of power electronic device application and universal and research and development, its principle is by voltage zero-cross detection control, utilize the fast response characteristic of thyristor, ensure to drop into capacitor when voltage zero-cross, avoid inrush phenomenon, utilize the current over-zero turn-off characteristic of thyristor self simultaneously, eliminate the problems such as the electric arc that capacitor exits.But, thyristor switch, due to silicon controlled conduction voltage drop characteristic, also exists very large power loss, and controllable silicon is easy loss parts, there will be instantaneous breakdown when temperature is too high, therefore thyristor switch must be equipped with large-area radiator even the equipment such as fan dispel the heat; Simultaneously controllable silicon is very responsive to voltage change ratio, if exist in electrical network harmonic wave larger time voltage zero-cross judge to occur deviation, easily make thyristor switch mislead and produce and shove greatly and make it damage.Simultaneously thyristor switch is except above characteristic, simultaneously due to complex structure, volume is large, loss is large, cost is high, poor reliability, seriously limits the application of thyristor switch.

Combination switch technology is exactly use in parallel with relay tip for thyristor, utilize the quick response of thyristor, realize voltage zero-cross input by thyristor to excise with current over-zero, continuous current is passed through by relay tip, doing so avoids the conduction loss problem of thyristor, it also avoid shoving when capacitor drops into.But due to the switching process of combination switch identical with the principle of the switching process of thyristor switch, all utilize the fast characteristic of the real-time response of thyristor and the zero-crossing switching characteristic of self to drop into realize voltage zero-cross, current over-zero exits, load current is born by relay after input, it fundamentally just solves the power dissipation concerns of thyristor switch, what the voltage zero-cross deviation that the solid switch of thyristor exists produced misleads, the du/dt sensitiveness of thyristor switch all fails to solve, thyristor switch throws the transient problems combination switch still existence of moving back and existing in process.Combination switch technology not only uses thyristor but also use relay simultaneously, so structure just becomes quite complicated.

Synchro switch (having another name called phase-selecting switch) is the technology of latest development in recent years, as the term suggests, make or the disconnection closed in the moment needed exactly of the contact of mechanical switch exactly.Make it close in the moment of voltage zero-cross by the mechanical switch (as relay) of control capacitor, thus realize capacitor no-flashy-flow drop into, electric current be zero moment disconnect, thus realize make and break contact without electric arc disjunction.But the basis of synchro switch is also mechanical switch, due to the operating characteristics of mechanical switch, the speed responsive of its action has delay, the problem such as otherness operate time of single mechanical switching element, synchro switch can not accurately accomplish real zero crossing throw move back cannot accomplish accurate zero passage throw move back to eliminate shove, the problem such as arcing.

In sum, A.C. contactor does not possess the function suppressing to shove and eliminate flashing, pure mechanicalness parts, and thyristor, combination switch, its common feature of synchro switch is that voltage zero-cross drops into, current over-zero exits, due to the error that voltage zero-cross detects, when voltage over zero, known according to the charging current computing formula ic=c* (du/dt) of capacitor, and when voltage zero-cross, from the sinuso sine protractor of voltage, the variation that tiny time difference near voltage over zero causes is very large, namely the du/dt produced is great, it is also great that input is shoved.

The advantage of mechanical switch (A.C. contactor, relay etc.) is that on-impedance is low, put into operation almost lossless, need not be equipped with heat dissipation equipment, and its maximum shortcoming postpones feature due to the action response of mechanical switch, cannot control accurately to close point moment point.

The advantage of reverse-blocking tetrode thyristor (or the controllable silicon parts in combination switch) is because its control response speed is fast, can accurately control to close point moment point, shortcoming is the conduction voltage drop due to silicon parts, larger loss is had when putting into operation, need to be equipped with heat dissipation equipment, simultaneously controllable silicon parts cross thermal breakdown, voltage jump causes characteristics such as misleading, also makes silicon parts more fragile.

Summary of the invention

The utility model, for problems such as capacitor shoving in switching process, arcings, proposes a kind of switching circuit for capacitor switching.Disclosed switching circuit takes full advantage of the loss-free feature of mechanical switch, make use of one-way conduction parts to realize capacitor precharge to reach capacitor residual voltage be line voltage peak value simultaneously, control switch drops at the peak point of line voltage, eliminate the action response delayed impact of mechanical switch, technology disclosed in the utility model achieves capacitor switching process no-flashy-flow, without arcing, after capacitor puts into operation, switching circuitry is lossless.

Switching circuit for capacitor switching of the present utility model is made up of road one-way conduction parts and a road controllable type mechanical switch Components Parallel Connection.Wherein, one-way conduction parts can be the parts that diode etc. has one-way conduction characteristic, and controllable type mechanical switch parts can be that magnetic latching relay, A.C. contactor etc. are without the switch block connecting loss.

Capacitor switching switching circuit of the present utility model is control controllable type mechanical switch parts to close logical near the peak point of line voltage when dropping into capacitor.Of the present utility model in the switching circuit of capacitor switching, before dropping into capacitor, due to the one-way conduction characteristic of one-way conduction element, electrical network realizes the charging to capacitor by one-way conduction element, makes the terminal voltage of capacitor and the peak value approximately equal of line voltage.Because minimum at the du/dt at electrical network crest voltage place, now drop into capacitor, even if controllable type mechanical switch operation of components exists action error, the du/dt now produced due to error is also less, effectively reduces shoving when capacitor drops into.

Capacitor switching switching circuit of the present utility model is control controllable type mechanical switch parts in disjunction in the single-phase conductive member ON time section of the switching circuit for capacitor switching of the present utility model when exiting capacitor.When exiting capacitor, the moment of the disconnection controllable type mechanical switch parts of selection is the ON time section of one-way conduction parts, and this time period is first cycle part higher than zero point of condenser current.After now controllable type mechanical switch parts disconnect, continue by after one-way conduction parts afterflow to condenser current zero crossing, capacitor exits electrical network automatically.This withdrawing mode can effectively reduce the operating characteristics error of controllable type mechanical switch parts, utilize the afterflow function of one-way conduction element, the zero passage realizing capacitor exits automatically, namely reduce the aging effects to controllability switch block, also eliminate capacitor and exit the Transient State Influence of process to electrical network.

Accompanying drawing explanation

Fig. 1 is the switching circuit principle schematic 1 of the utility model capacitor switching

Fig. 2 is the switching circuit principle schematic 2 of the utility model capacitor switching

Fig. 3 is that the switching circuit of the utility model capacitor switching does not drop into capacitor status

Fig. 4 is that the switching circuit of the utility model capacitor switching drops into capacitor process status

Fig. 5 is that the switching circuit of the utility model capacitor switching exits capacitor process status

Fig. 6 is that the switching circuit of the utility model capacitor switching drops into process capacitor electrode stream mode

Fig. 7 is that the switching circuit of the utility model capacitor switching exits process capacitor electrode stream mode

Embodiment

Further the utility model content is described below in conjunction with drawings and Examples:

Be illustrated in figure 1 the circuit theory schematic diagram of the switching circuit of capacitor switching of the present utility model, it is made up of an an one-way conduction element D and controllable type switch element K parallel connection, in the present embodiment, one-way conduction element D is diode, and controllable type switch element K is magnetic latching relay.

Be illustrated in figure 3 switching circuit state before input of the utility model capacitor switching, now capacitor does not drop into electrical network, due to the one-way conduction characteristic of D, now capacitor and electrical network fail to form complete bi-directional path, only when grid side voltage peak is higher than capacitor side voltage, electrical network is charged to capacitor by the one-way conduction characteristic of D, makes the terminal voltage of capacitor and electrical network crest voltage keep approximately equal in real time.

Be illustrated in figure 4 the switching circuit of the utility model capacitor switching in input process status, by controlling controllable type switch element K, it is made to close line voltage peak value place (now the terminal voltage of capacitor is similar to electrical network peak value), bi-directional path is formed through controllable type switch element and electrical network, now condenser current then drops into electrical network from zero point, runs in the input electrical network of capacitor.

The switching circuit being illustrated in figure 5 the utility model capacitor switching is exiting process status, by controlling controllable type switch element K, it is made to disconnect in first cycle of condenser current, after now K disconnects, the afterflow of this half-wave is completed by one-way conduction element D, when this half cycles zero crossing, automatically realize turning off.

As shown in Figure 6, for the real work test of the switching circuit of the utility model capacitor switching drops into waveform.As apparent from the current waveform of capacitor can, condenser current is dropped into by current zero-crossing point, access electrical network, no-flashy-flow.

As shown in Figure 7, for waveform is exited in the real work test of the switching circuit of the utility model capacitor switching.As apparent from the current waveform of capacitor can, the electric current of capacitor automatically shuts down at current zero-crossing point, exits electrical network, and turn off process is that effective current over-zero turns off.

Claims

1. for a switching circuit for capacitor switching, it is characterized in that: the switching circuit for capacitor switching is made up of road one-way conduction parts and a road controllable type mechanical switch Components Parallel Connection.

2. as claimed in claim 1 for the switching circuit of capacitor switching, it is characterized in that: one-way conduction parts can be the parts that diode etc. has one-way conduction characteristic, and controllable type mechanical switch parts can be the controllable type such as magnetic latching relay, A.C. contactor mechanical switch parts.

3., as claimed in claim 1 for the switching circuit of capacitor switching, it is characterized in that: the conducting direction of one-way conduction parts can for grid side to capacitor side to, also can be capacitor side direction grid side direction.