CN109742775A - Three-phase load balancing device and method - Google Patents
Three-phase load balancing device and method Download PDFInfo
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Abstract
The present invention discloses a kind of three-phase load balancing device and method, wherein the three-phase load balancing device includes separate detection module, for detecting the open and-shut mode of separate on-load switch where to be switched load；Zero point detection module, for detecting switchable load place separate current zero state and point of zero voltage state；Controller, it is all connected with separate detection module, zero point detection module, each phase load switch, where the to be switched load that separate detection module detects when separate on-load switch closure, controller controls the separate on-load switch disconnection in current zero state in be switched load place, and to be switched load is cut switching phase line in point of zero voltage state；Realize can accurate detection load switch state, avoid the problem that the load of the power grid on-load switch in commutation process be not responding to and caused by phase fault, on-load switch damage.
Description
Technical field
The present invention relates to mains-power circuit technical field, in particular to a kind of three-phase load balancing device and method.
Background technique
In low voltage electric network, the overwhelming majority is three-phase four-wire power supply network, and since most of electrical equipment is single
Phase electricity consumption, therefore normal the phenomenon that will appear three-phase load unbalance.The imbalance of three-phase load can cause transformer and power grid
Harm causes delivery efficiency and transformer damage, damage and power transmission line accelerated ageing of supply transformer etc. to influence.Thus
In power grid, it is often necessary to dynamic equilibrium assignmen is carried out to Three-Phase Transformer load, to keep Three-Phase Transformer load
Relative equilibrium reduces line facility loss, ensures the safety of power equipment.And balancing the load most effective way is exactly that load is opened
Switch mode is closed, software approach is mostly used to carry out zero point acquisition to three-phase voltage respectively at present, is broken after receiving commutation order
It opens current closure mutually to switch, then closure needs the separate switch being closed.In this process, because can not judge to need to disconnect
Switch whether disconnected, so be closed needed for closure separate switch when, it is possible to will lead to the tight of phase fault and open circuit
Weigh power grid accident.
Summary of the invention
It is negative to solve power grid in the prior art by providing a kind of three-phase load balancing device and method for the embodiment of the present application
Lotus in commutation equilibrium process, on-load switch be not responding to and caused by phase fault, on-load switch damage the problem of, realizing can
Accurate detection load switch state, avoids the load of power grid phase fault in commutation process；In current zero and point of zero voltage
State carries out load switching phase, in the case where avoiding high voltage, high current, causes the current or voltage of incision moment excessive and right
On-load switch is caused to damage or be damaged, and further ensures the safety and accuracy of load transfer.
The embodiment of the present application provides a kind of three-phase load balancing device, comprising:
Separate detection module, for detecting the open and-shut mode of the separate on-load switch in be switched load place；
Zero point detection module, for detecting switchable load place separate current zero state and point of zero voltage state；
Controller is all connected with on-load switch described in the separate detection module, the zero point detection module, each phase, when
Where the to be switched load that the separate detection module detects when separate on-load switch closure, described in the controller control
Separate on-load switch is disconnected in current zero state where to be switched load, will be described to be switched in point of zero voltage state
Load incision switching phase line.
Optionally, the time interval between the current zero state and point of zero voltage state is less than or equal to the three-phase
Time alternating current monocycle of power grid where balancing device.
Optionally, the separate detection module includes acquisition unit and signal conversion unit, the detection of the acquisition unit
End and separate connection where the to be switched load, the output end of the acquisition unit are defeated with the signal conversion unit
Enter end connection, the output end of the signal conversion unit is connect with the controller；The acquisition unit for detect it is described to
The open and-shut mode is converted to correspondence by the open and-shut mode of separate on-load switch, the signal conversion unit where switchable load
Level signal be transmitted to the controller.
Optionally, the acquisition unit includes rectifier bridge, optocoupler, first resistor and second resistance, the rectifier bridge
First input end is as separate connection where the collection terminal and the to be switched load of the acquisition unit, and the of the rectifier bridge
Two input terminals are connect with the output end of on-load switch separate where the to be switched load, the first output end of the rectifier bridge
The anode of light emitting diode through first resistor and optocoupler connects, and the second output terminal of the rectifier is through second resistance and optocoupler
Light emitting diode cathode connection；The collector of the phototriode of the optocoupler as acquisition unit output end with it is described
The input terminal of signal conversion unit connects, the emitter ground connection of the phototriode of the optocoupler.
Optionally, the acquisition unit further includes first diode, the anode of the first diode and the rectifier
Second output terminal, the common end connection between second resistance, the cathode of the first diode and the first resistor, optocoupler
Light emitting diode anode between common end connection.
Optionally, the signal conversion unit includes NOT gate logic components, 3rd resistor, the 4th resistance, the 5th resistance and
One end of one capacitor, the 3rd resistor is connect with power supply, and the other end of the 3rd resistor is converted as the signal
The input terminal of unit is connect with one end of the output end of the acquisition unit, the 4th resistance, the other end of the 4th resistance with
The input terminal of the NOT gate logic components connects, and the output end of the NOT gate logic components is connect with one end of the 5th resistance, institute
The other end for stating the 5th resistance is connect as the output end of the signal conversion unit with the controller；The first capacitor
One end is connect with the power supply, and the other end is connect with the input terminal of the NOT gate logic components.
Optionally, the signal conversion unit further includes the second diode, the anode of second diode with it is described non-
The input terminal of gate logic part connects, the common end between the cathode and the 3rd resistor, the 4th resistance of second diode
Connection.
The embodiment of the present application also provides a kind of three-phrase burden balance methods, comprising the following steps:
Receive commutation instruction；
Detect the open and-shut mode of the separate on-load switch in be switched load place；
When separate on-load switch is closed state where the to be switched load, the to be switched load incision is controlled
Switch in phase line.
Optionally, the step in the control to be switched load incision switching phase line specifically:
Detect to be switched load place separate current zero state and point of zero voltage state；
It is separate where the control to be switched load to bear when to be switched load place is separate is in current zero state
Lotus switch disconnects；
In next adjacent point of zero voltage state, control in the to be switched load incision switching phase line.
Optionally, the time interval between the current zero state and next adjacent point of zero voltage state is less than or waits
Time alternating current monocycle of power grid where the three-phase equilibrium device.
One or more technical solutions provided in the embodiments of the present application have at least the following technical effects or advantages:
1, the open and-shut mode of the separate on-load switch in be switched load place is detected due to using separate detection module, and
On the basis of on-load switch closure, separate the current zero state and point of zero voltage state is detected, in current zero state
Separate on-load switch where to be switched load is disconnected, and in next adjacent point of zero voltage state by the to be switched load
Incision switching phase line, so, solve network load in commutation equilibrium process, on-load switch state it is uncertain and caused by
The problem of phase fault；And in current zero and point of zero voltage state load switching phase is carried out, avoid high voltage, high current
In the case of, it causes the current or voltage of incision moment excessive and on-load switch is caused to damage or be damaged.
2, the scheme of load switching is completed in 20ms due to using, so, solve accurate switchable load switch
Problem improves the effect of the load safety that load shifts in commutation process and accuracy.
3, the open and-shut mode of separate detection module on-load switch collected is converted into corresponding level due to using
Signal is transmitted to the scheme of controller, so, it solves on-load switch in controller control commutation process and is not responding to asking for movement
Topic improves the effect of the precision of control on-load switch switching.
4, the detection of the open and-shut mode of on-load switch is realized due to using specific hardware circuit and by open and-shut mode
It is converted into the scheme of corresponding electric signal transmission, so, solve on-load switch status data in traditional software control commutation process
Caused by acquisition inaccuracy the problem of balancing the load failure, the effect of balancing the load accuracy is improved.
Detailed description of the invention
In order to more clearly explain the embodiment of the invention or the technical proposal in the existing technology, to embodiment or will show below
There is attached drawing needed in technical description to be briefly described, it should be apparent that, the accompanying drawings in the following description is only this
Some embodiments of invention for those of ordinary skill in the art without creative efforts, can be with
The structure shown according to these attached drawings obtains other attached drawings.
Fig. 1 is the structural schematic diagram of one embodiment of three-phase load balancing device of the present invention；
Fig. 2 is each phase current of three-phase load balancing device of the present invention and voltage waveform view；
Fig. 3 is the circuit connection diagram of one embodiment of three-phase load balancing device of the present invention；
Fig. 4 is the flow diagram of one embodiment of three-phrase burden balance method of the present invention；
Fig. 5 is the specific flow chart of step S300 in Fig. 4.
Drawing reference numeral explanation:
| Label | Title | Label | Title |
| 100 | Separate detection module | R1 | First resistor |
| 110 | Acquisition module | R2 | Second resistance |
| 120 | Signal conversion unit | R3 | 3rd resistor |
| 200 | Zero point detection module | R4 | 4th resistance |
| 300 | Controller | R5 | 5th resistance |
| 400 | Each phase load switch | C1 | First capacitor |
| U1 | Rectifier bridge | D1 | First diode |
| U2 | Optocoupler | D2 | Second diode |
| U3 | NOT gate logic components |
The embodiments will be further described with reference to the accompanying drawings for the realization, the function and the advantages of the object of the present invention.
Specific embodiment
Following will be combined with the drawings in the embodiments of the present invention, and technical solution in the embodiment of the present invention carries out clear, complete
Site preparation description, it is clear that described embodiment is only a part of the embodiments of the present invention, instead of all the embodiments.Base
Embodiment in the present invention, it is obtained by those of ordinary skill in the art without making creative efforts it is all its
His embodiment, shall fall within the protection scope of the present invention.
It is to be appreciated that the directional instruction (such as up, down, left, right, before and after ...) of institute is only used in the embodiment of the present invention
In explaining in relative positional relationship, the motion conditions etc. under a certain particular pose (as shown in the picture) between each component, if should
When particular pose changes, then directionality instruction also correspondingly changes correspondingly.
In addition, the description for being related to " first ", " second " etc. in the present invention is used for description purposes only, and should not be understood as referring to
Show or imply its relative importance or implicitly indicates the quantity of indicated technical characteristic." first ", " are defined as a result,
Two " feature can explicitly or implicitly include at least one of the features.In addition, the technical solution between each embodiment can
It to be combined with each other, but must be based on can be realized by those of ordinary skill in the art, when the combination of technical solution occurs
Conflicting or cannot achieve when, will be understood that the combination of this technical solution is not present, also not the present invention claims protection model
Within enclosing.
In order to better understand the above technical scheme, in conjunction with appended figures and specific embodiments to upper
Technical solution is stated to be described in detail.
Embodiment one
Referring to Fig.1, the embodiment of the present application provides a kind of three-phase load balancing device, the three-phase load balancing device packet
It includes:
Separate detection module 100, for detecting the open and-shut mode of the separate on-load switch in be switched load place；
Zero point detection module 200, for detecting switchable load place separate current zero state and point of zero voltage state；
Controller 300, with on-load switch described in the separate detection module 100, the zero point detection module 200, each phase
It is all connected with, where the to be switched load that the separate detection module 100 detects when separate on-load switch closure, the control
Device 300 processed controls the separate on-load switch disconnection in current zero state in the to be switched load place, dotted in voltage zero
By the to be switched load incision switching phase line when state.
In the present embodiment, for three phase network, 100 settable three groups of separate detection module is respectively connected to power grid
In each phase, for detecting the open and-shut mode of each on-load switch for treating each other switchable load, where detecting to be switched load
When separate on-load switch is off-state, then illustrate that the separate load carried out epicycle balance adjustment, then epicycle
No longer the separate load is adjusted；When separate on-load switch is closed state where detecting to be switched load,
Then illustrate that the separate load does not carry out epicycle balance adjustment also, then can be balanced adjusting, load commutation balance can be carried out
It adjusts.
In addition, in the present embodiment, which phase line load cuts, the on-load switch of the phase line is in off state.
During carrying out load commutation balance adjustment, current to be switched load incision need to be switched in phase line, herein
In the process, it needs first to disconnect the on-load switch of phase where current to be switched load, then again by the to be switched load incision switching
In phase line, to complete current separate epicycle balance adjustment.
In above-mentioned load commutation process, consider in terms of exchanging power load, in load commutation, we should be
Separate line load, which is under minimum state, where to be switched load carries out commutation.Because being disconnected when line load is larger
Separate on-load switch can cause damage even to damage to on-load switch itself where to be switched load；And switching phase voltage compared with
To be switched load is cut in the case where height suddenly, then be easy to cause the electric current of incision moment excessive and on-load switch is caused to damage
Or damage.Therefore, the opening operation that on-load switch should be carried out in route current zero, because line load is smaller at this time,
It can avoid disconnecting the separate on-load switch in be switched load place to damage caused by on-load switch itself or even damage；Switching
To be switched load is cut when phase voltage zero point, is similarly to avoid the electric current of incision moment excessive and cause to damage to on-load switch
Or damage.
Through the above scheme, network load is in commutation equilibrium process, can accurate detection load switch state, avoid power grid
Load in commutation process phase fault；And load switching phase is carried out in current zero and point of zero voltage state, avoids height
In the case where voltage, high current, causes the current or voltage of incision moment excessive and on-load switch is caused to damage or be damaged, into
One step ensure that the safety and accuracy of load transfer.
Specifically, referring to Fig. 2, in the present embodiment, between the current zero state and the point of zero voltage state
Time alternating current monocycle of power grid where time interval is less than or equal to the three-phase equilibrium device.
Each separate electric current and point of zero voltage detection are divided into two aspects, are the detection of rising edge zero point and failing edge zero respectively
Point detection.Real-time sampling can be carried out to electric current, voltage signal by hardware circuit, and (software can integrate combination auxiliary software
In controller 300) voltage, the electric current of sampling are handled, it obtains the waveform diagram of electric current and voltage, is carried out by waveform diagram
Zero point fitting then can accurately prejudge the time that electric current and point of zero voltage signal arrive in advance.In general, arriving in current zero signal
Time and two timing nodes of time for arriving of next adjacent point of zero voltage signal complete a load commutation processes.Into
It, can be accurately separate where the current to be switched load of disconnection in current zero when the disconnection of row on-load switch and Operating In Persistent Current Mode
On-load switch, and accurately cut commutation on-load switch in next adjacent point of zero voltage.In China, the exchange of power grid
The frequency of electricity is generally 50Hz, then time monocycle of power grid alternating current is 20ms, the then total commutation of a load commutation process
The switch motion time, (on-load switch comprising on-load switch turn-off time separate where to be switched load and switching phase line closed
Close the time) it must be completed in 20ms (monocycle of power grid alternating current).
It is obtained according to theoretical analysis result, a most short load commutation process total phase-change switch actuation time is 20/
6ms, maximum duration 100/6ms.It carries out intersecting there are two separate zero points within the monocycle, therefore, be switched in each phase load
In 400 handoff procedure, it is necessary to obtain point of zero voltage rapidly after current zero, could accurately capture and carry out on-load switch
Switching Operating In Persistent Current Mode, complete the commutation balancing work of line load.
Further, referring to Fig. 3, in the present embodiment, the separate detection module 100 includes acquisition unit 110 and letter
Separate connection where number converting unit 120, the test side of the acquisition unit 110 and the to be switched load, it is described to adopt
The output end of collection unit 110 is connect with the input terminal of the signal conversion unit 120, the output of the signal conversion unit 120
End is connect with the controller 300；The acquisition unit 110 is used to detect the separate on-load switch in the to be switched load place
Open and-shut mode, the open and-shut mode is converted to corresponding level signal and is transmitted to the control by the signal conversion unit 120
Device 300 processed.
In the present embodiment, the acquisition unit 110 of each separate detection module 100 with where corresponding to be switched load
Separate connection acquires the open and-shut mode of the separate on-load switch in be switched load place by the test side of acquisition unit 110.When
Acquisition unit 110 collect on-load switch be closed state when, then the closed state is transmitted to signal conversion unit 120, should
The closed state is converted to corresponding level signal and is transmitted to controller 300 by signal conversion unit 120, in the present embodiment,
The closed state of on-load switch is converted to low level signal by signal conversion unit 120, and the off-state of on-load switch is converted
For high level signal.When the signal that controller 300 receives the transmission of signal conversion unit 120 is low level signal, then determine
The on-load switch of phase where the to be switched load being connected with the separate detection module 100 is closed state, then it is flat can to carry out commutation
Weigh load operation；When controller 300 receive signal conversion unit 120 transmission signal be high level signal when, then determine with
The on-load switch of phase is off-state where the connected to be switched load of the separate detection module 100, then balances without commutation
Load operation.Certainly, signal conversion unit 120 can also be converted to the closed state for the on-load switch that acquisition unit 110 detects
The off-state of on-load switch is converted to low level signal by high level signal.
Through the above scheme, by being converted to pair the open and-shut mode of separate detection module 100 on-load switch collected
The level signal answered is transmitted to controller 300, solves on-load switch in the control commutation process of controller 300 and is not responding to movement
Problem improves the effect of the precision of control on-load switch switching.
Specifically, the acquisition unit 110 includes rectifier bridge U1, optocoupler U2, first resistor R1 and second resistance R2, institute
The first input end for stating rectifier bridge U1 connects as separate Ux where the collection terminal and the to be switched load of the acquisition unit 110
It connects, the output end Uout of separate on-load switch connects where the second input terminal of the rectifier bridge U1 and the to be switched load
It connects, the first output end of the rectifier bridge U1 is connect through first resistor R1 with the anode of the light emitting diode of optocoupler U2, described whole
The second output terminal of stream device is connect through second resistance R2 with the cathode of the light emitting diode of optocoupler U2；Photosensitive the three of the optocoupler U2
The collector of pole pipe is connect as the output end of acquisition unit 110 with the input terminal of the signal conversion unit 120, the optocoupler
The emitter of the phototriode of U2 is grounded.
In the present embodiment, the balanced load vector sum of three-phase alternating current is 0, between any two-phase of three-phase alternating current
Angle is 120 °, i.e., voltage between phases is 380V.When separate on-load switch disconnects where to be switched load, the two of rectifier bridge U1
Input terminal is out-phase, and voltage is 380V exchange；Where to be switched load when separate on-load switch closure, the two of rectifier bridge U1
Input terminal is same phase, voltage 0V.
Each acquisition unit 110 acquires the open and-shut mode of the on-load switch of corresponding phase, in the present embodiment, when to be switched
Where load when separate on-load switch closure, then the voltage of the first input end of rectifier bridge U1 and the second input terminal is identical, phase
Position is also identical, is at this time 0 by the rectified voltage of rectifier bridge U1, the first output end and second output terminal Non voltage output, then light
Coupling U2 is not turned on, the collector Non voltage output of optocoupler U2.
When separate on-load switch disconnects where to be switched load, then the first input end of rectifier bridge U1 and the second input
The voltage-phase at end is different, and any two-phase for being equivalent to three-phase alternating current is respectively connected to two input terminals of rectifier bridge U1.Lead at this time
The rectified voltage of over commutation bridge U1 is the exchange of 380V, and after rectified, the first output end and second output terminal have voltage output, then
Optocoupler U2 conducting, the collector of optocoupler U2 have voltage output.
In the present embodiment, the effect of first resistor R1 and second resistance R2 are metering function, and resistance value can be according to reality
Border demand is selected.
Further, acquisition unit 110 further includes first diode D1, the anode of the first diode D1 with it is described whole
Flow the common end connection between the second output terminal of device, second resistance R2, the cathode of the first diode D1 and described first
Common end connection between the anode of the light emitting diode of resistance R1, optocoupler U2.
The effect of first diode D1 is pressure stabilizing, the effect of filtering clutter signal, when rectifier bridge U1 has voltage output, is led to
Cross first diode D1, it is possible to provide the both ends of light emitting diode of the stable voltage signal load in optocoupler U2.
Further, the signal conversion unit 120 includes NOT gate logic components U3,3rd resistor R3, the 4th resistance R4, the
Five resistance R5 and first capacitor C1, one end of the 3rd resistor R3 are connect with power supply VCC, and the 3rd resistor R3's is another
Input terminal and the output end of the acquisition unit 110, one end of fourth resistance R4 of the one end as the signal conversion unit 120
Connection, the other end of the 4th resistance R4 are connect with the input terminal of the NOT gate logic components U3, the NOT gate logic components U3's
Output end is connect with one end of the 5th resistance R5, and the other end of the 5th resistance R5 is as the signal conversion unit
120 output end is connect with the controller 300；One end of the first capacitor C1 is connect with the power supply VCC, another
End is connect with the input terminal of the NOT gate logic components U3.
When the output of 110 no-voltage signal of acquisition unit, i.e., separate on-load switch is in closure where to be switched load
When state, then power supply VCC is loaded onto the input terminal of NOT gate logic components U3 by 3rd resistor R3, the 4th resistance R4, quite
In the input terminal input high level signal in NOT gate logic components U3, after NOT gate logic components U3, low level signal is exported, by the
Five resistance R5 are exported to controller 300.Then as previously mentioned, when separate detection unit exports low level signal to controller 300,
It then can determine that the separate on-load switch in load place to be detected is closed state.In the present embodiment, 3rd resistor R3, the 4th electricity
It hinders R4 and plays metering function, super-high-current is prevented to be input to the input terminal of NOT gate logic components U3 and damage NOT gate logic components U3.
Separate on-load switch, which is in, when acquisition unit 110 has voltage signal output, i.e., where to be switched load disconnects
When state, then the phototriode of optocoupler U2 is on state, and the emitted pole of the collector of phototriode is down for relatively
Low level signal, become after the RC circuit shaping filter constituted through first capacitor C1 with the 4th resistance R4 low level be loaded onto it is non-
The input terminal of gate logic part U3 exports high level signal, is exported by the 5th resistance R5 to controller after NOT gate logic components U3
300.Then as previously mentioned, then can determine that load institute to be detected when separate detection unit exports high level signal to controller 300
It is off-state in separate on-load switch.
In the present embodiment, the 5th resistance R5 role is metering function.
Further, the signal conversion unit 120 further includes the second diode D2, the anode of the second diode D2
It is connect with the input terminal of the NOT gate logic components U3, the cathode and the 3rd resistor R3 of the second diode D2, the 4th electricity
Hinder the common end connection between R4.
The effect of second diode D2 is also pressure stabilizing, the effect of filtering clutter signal, passes through the second diode D2, it is possible to provide
Input terminal of the stable voltage signal load in NOT gate logic components U3.
Based on the same inventive concept, the embodiment of the invention also provides balance sides corresponding to balancing device in embodiment one
Method is shown in embodiment two.
Embodiment two
Referring to Fig. 4, the present embodiment provides a kind of three-phrase burden balance methods, comprising the following steps:
Step S100: commutation instruction is received；
Step S200: the open and-shut mode of the separate on-load switch in be switched load place is detected；
Step S300: it when separate on-load switch is closed state where the to be switched load, controls described to be cut
It changes in load incision switching phase line.
The method of the present embodiment is what the balancing device based on embodiment one carried out, with the original of the device of illustrated embodiments one
Reason is illustrated the method for the present embodiment, and for three phase network, when needing to carry out balancing the load, then the three-phrase burden balance is filled
Commutation instruction will be received by setting, and be will start separate detection module 100 first and be detected to the open and-shut mode of on-load switch, separate
It 100 settable three groups of detection module, is respectively connected in each phase of power grid, for detecting each load for treating each other switchable load
The open and-shut mode of switch then illustrates that this is separate when separate on-load switch is off-state where detecting to be switched load
Load carried out epicycle balance adjustment, then epicycle is no longer adjusted the separate load；It is to be cut when detecting
When to change separate on-load switch where load be closed state, then illustrate that the separate load does not carry out epicycle balance adjustment also,
It can be then balanced adjusting, load commutation balance adjustment can be carried out.
In addition, in the present embodiment, which phase line load cuts, the on-load switch of the phase line is in off state.
During carrying out load commutation balance adjustment, current to be switched load incision need to be switched in phase line, herein
In the process, it needs first to disconnect the on-load switch of phase where current to be switched load, then again by the to be switched load incision switching
In phase line, to complete current separate epicycle balance adjustment.
Through the above scheme, network load is in commutation equilibrium process, can accurate detection load switch state, avoid power grid
Load in commutation process phase fault, ensure that load transfer safety and accuracy.
Further, referring to Fig. 5, in step S300, in the control to be switched load incision switching phase line
The step of specifically:
Step S310: to be switched load place separate current zero state and point of zero voltage state are detected；
Step S320: when to be switched load place is separate is in current zero state, the to be switched load institute is controlled
It is disconnected in separate on-load switch；
Step S330: in next adjacent point of zero voltage state, the to be switched load incision switching phase line is controlled
In.
In above-mentioned load commutation process, consider in terms of exchanging power load, in load commutation, we should be
Separate line load, which is under minimum state, where to be switched load carries out commutation.Because being disconnected when line load is larger
Separate on-load switch can cause damage even to damage to on-load switch itself where to be switched load；And switching phase voltage compared with
To be switched load is cut in the case where height suddenly, then be easy to cause the electric current of incision moment excessive and on-load switch is caused to damage
Or damage.Therefore, the opening operation that on-load switch should be carried out in route current zero, because line load is smaller at this time,
It can avoid disconnecting the separate on-load switch in be switched load place to damage caused by on-load switch itself or even damage；Switching
To be switched load is cut when phase voltage zero point, is similarly to avoid the electric current of incision moment excessive and cause to damage to on-load switch
Or damage.
By being carried out in the case that load switching phase avoids high voltage, high current in current zero and point of zero voltage state,
Cause incision moment current or voltage it is excessive and to on-load switch cause damage or damage, further ensure load transfer
Safety and accuracy.
Further, the time interval between the current zero state and next adjacent point of zero voltage state be less than or
Equal to time alternating current monocycle of power grid where the three-phase equilibrium device.
Each separate electric current and point of zero voltage detection are divided into two aspects, are the detection of rising edge zero point and failing edge zero respectively
Point detection.Real-time sampling can be carried out to electric current, voltage signal by hardware circuit, and (software can integrate combination auxiliary software
In controller 300) voltage, the electric current of sampling are handled, it obtains the waveform diagram of electric current and voltage, is carried out by waveform diagram
Zero point fitting then can accurately prejudge the time that electric current and point of zero voltage signal arrive in advance.In general, arriving in current zero signal
Time and two timing nodes of time for arriving of next adjacent point of zero voltage signal complete a load commutation processes.Into
It, can be accurately separate where the current to be switched load of disconnection in current zero when the disconnection of row on-load switch and Operating In Persistent Current Mode
On-load switch, and accurately cut commutation on-load switch in next adjacent point of zero voltage.In China, the exchange of power grid
The frequency of electricity is generally 50Hz, then time monocycle of power grid alternating current is 20ms, the then total commutation of a load commutation process
The switch motion time, (on-load switch comprising on-load switch turn-off time separate where to be switched load and switching phase line closed
Close the time) it must be completed in 20ms (monocycle of power grid alternating current).
It is obtained according to theoretical analysis result, a most short load commutation process total phase-change switch actuation time is 20/
6ms, maximum duration 100/6ms.It carries out intersecting there are two separate zero points within the monocycle, therefore, be switched in each phase load
In 400 handoff procedure, it is necessary to obtain point of zero voltage rapidly after current zero, could accurately capture and carry out on-load switch
Switching Operating In Persistent Current Mode, complete the commutation balancing work of line load.
The above description is only a preferred embodiment of the present invention, is not intended to limit the scope of the invention, all at this
Under the inventive concept of invention, using equivalent structure transformation made by description of the invention and accompanying drawing content, or directly/use indirectly
It is included in other related technical areas in scope of patent protection of the invention.
Claims (10)
1. a kind of three-phase load balancing device characterized by comprising
Separate detection module, for detecting the open and-shut mode of the separate on-load switch in be switched load place；
Zero point detection module, for detecting switchable load place separate current zero state and point of zero voltage state；
Controller is all connected with, when described with on-load switch described in the separate detection module, the zero point detection module, each phase
Where the to be switched load that separate detection module detects when separate on-load switch closure, the controller control is described to be cut
The separate on-load switch disconnection in current zero state in load place is changed, in point of zero voltage state by the to be switched load
Incision switching phase line.
2. three-phase load balancing device as described in claim 1, which is characterized in that the current zero state and point of zero voltage
Time alternating current monocycle of power grid where time interval between state is less than or equal to the three-phase equilibrium device.
3. three-phase load balancing device as claimed in claim 1 or 2, which is characterized in that the separate detection module includes adopting
Collect unit and signal conversion unit, separate connection where the test side of the acquisition unit and the to be switched load is described to adopt
The output end of collection unit is connect with the input terminal of the signal conversion unit, the output end of the signal conversion unit and the control
Device connection processed；The acquisition unit is used to detect the open and-shut mode of the separate on-load switch in the to be switched load place, described
The open and-shut mode is converted to corresponding level signal and is transmitted to the controller by signal conversion unit.
4. three-phase load balancing device as claimed in claim 3, which is characterized in that the acquisition unit includes rectifier bridge, light
Coupling, first resistor and second resistance, the first input end of the rectifier bridge as the acquisition unit collection terminal with it is described
Separate connection where to be switched load, the second input terminal of the rectifier bridge are opened with load separate where the to be switched load
The output end of pass connects, and the first output end of the rectifier bridge is connected through the anode of the light emitting diode of first resistor and optocoupler,
The cathode of light emitting diode of the second output terminal of the rectifier through second resistance and optocoupler connects；Photosensitive the three of the optocoupler
The collector of pole pipe is connect as the output end of acquisition unit with the input terminal of the signal conversion unit, the optocoupler it is photosensitive
The emitter of triode is grounded.
5. three-phase load balancing device as claimed in claim 4, which is characterized in that the acquisition unit further includes the one or two pole
Pipe, the common end between the second output terminal of the anode of the first diode and the rectifier, second resistance connects, described
The cathode of first diode and the first resistor, optocoupler light emitting diode anode between common end connect.
6. three-phase load balancing device as claimed in claim 3, which is characterized in that the signal conversion unit includes that NOT gate is patrolled
Part, 3rd resistor, the 4th resistance, the 5th resistance and first capacitor are collected, one end of the 3rd resistor is connect with power supply, institute
The other end of 3rd resistor is stated as the input terminal of the signal conversion unit and output end, the 4th resistance of the acquisition unit
One end connection, the other end of the 4th resistance connect with the input terminal of the NOT gate logic components, the NOT gate logic components
Output end is connect with one end of the 5th resistance, output of the other end of the 5th resistance as the signal conversion unit
End is connect with the controller；One end of the first capacitor is connect with the power supply, the other end and the non-gate logic
The input terminal of part connects.
7. three-phase load balancing device as claimed in claim 6, which is characterized in that the signal conversion unit further includes second
Diode, the anode of second diode are connect with the input terminal of the NOT gate logic components, the cathode of second diode
Common end between the 3rd resistor, the 4th resistance is connect.
8. a kind of three-phrase burden balance method, which comprises the following steps:
Receive commutation instruction；
Detect the open and-shut mode of the separate on-load switch in be switched load place；
When separate on-load switch is closed state where the to be switched load, the to be switched load incision switching is controlled
In phase line.
9. three-phrase burden balance method as claimed in claim 8, which is characterized in that the control to be switched load incision
Switch the step in phase line specifically:
Detect to be switched load place separate current zero state and point of zero voltage state；
When to be switched load place is separate is in current zero state, controls the separate load in the to be switched load place and open
Shutdown is opened；
In next adjacent point of zero voltage state, control in the to be switched load incision switching phase line.
10. three-phrase burden balance method as claimed in claim 8 or 9, which is characterized in that the current zero state with it is next
The alternating current list of power grid where time interval between adjacent point of zero voltage state is less than or equal to the three-phase equilibrium device
Cycle time.
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