CN108336756A - Double grid-connected Switch Three-Phase locking phase frequency conversion all-in-one machines and phase-lock technique - Google Patents
Double grid-connected Switch Three-Phase locking phase frequency conversion all-in-one machines and phase-lock technique Download PDFInfo
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- CN108336756A CN108336756A CN201810084657.9A CN201810084657A CN108336756A CN 108336756 A CN108336756 A CN 108336756A CN 201810084657 A CN201810084657 A CN 201810084657A CN 108336756 A CN108336756 A CN 108336756A
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- 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
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R25/00—Arrangements for measuring phase angle between a voltage and a current or between voltages or currents
Abstract
Double grid-connected Switch Three-Phase locking phase frequency conversion all-in-one machines and phase-lock technique, the all-in-one machine is made of major loop and control loop, and major loop is by frequency converter, four vacuum contactors, two voltage hall sensors and motor are constituted, and control loop is made of four intermediate relays, PLC and control switch；When system works, the locking phase of start-up course and its output voltage to network voltage is completed by frequency converter, PLC completes the switch control to vacuum contact by the action of control intermediate relay, frequency converter is powered to motor when to realize startup, when stable state, the function that power grid is powered to motor after the completion of locking phase and vacuum contactor switch is waited for；The present invention uses three-phase Phase Lock Technique that grid phase and frequency converter output voltage phase into horizontal lock, to be locked to network voltage using PI controllers；Ensure that power supply handoff procedure occur when, the two voltage-phase it is consistent.
Description
Technical field
The present invention relates to a kind of motor drag equipment, and in particular to a kind of double grid-connected Switch Three-Phase locking phase frequency conversion all-in-one machines and
Phase-lock technique.
Background technology
Requirement with coal enterprises in China to the safety of production equipment increasingly improves, more and more mine motor enterprises
Frequency converter and motor are integrated by industry consideration to be designed, and all-in-one machine is also increasingly welcome by market.
Traditional all-in-one machine is the fitting together the equipment such as frequency converter, PLC, relay and motor of machinery, one
The use difficulty for determining to simplify equipment in degree, improves the safety of dragging system.However in the actual production process, some
Motor long-term work does not need to frequency converter and does too many control under rated voltage and rated speed, if at this time by the electricity of motor
Source is changed to the better power grid of sine by frequency converter, then electric efficiency and the reliability of dragging system will further improve again.
Although however the electric voltage frequency and amplitude of the output of declared working condition low-converter are closer to power grid, can not ensure theirs
Phase is identical, if directly switching over, it is possible to create larger dash current causes enormous impact to motor and power grid.
In addition to this, for traditional all-in-one machine in order to realize the function of power supply switching, first having to test when mounted makes motor just
The phase sequence of power grid when turning, and motor can only could complete the switching of power supply when rotating forward, and this feature makes it use
It is significantly limited in serious forgiveness and degree of freedom.
Invention content
In order to avoid the failure that existing all-in-one machine may occur when in use, and its performance deficiency is made up, this hair
Bright is designed to provide a kind of pair of grid-connected Switch Three-Phase locking phase frequency conversion all-in-one machine and phase-lock technique, by three-phase locking phase Phase Lock Technique
It is combined with the operational capability of frequency converter in all-in-one machine, realizes that frequency converter output to the locking phase of network voltage, ensures power supply
The input voltage phase of the front and back motor of switching and frequency variation are little, greatly reduce the dash current of handoff procedure, increase
The reliability of system；In addition to this, the wiring of power grid to motor uses biswitch connection --- and power grid positive sequence and negative phase-sequence are in parallel, so
After be supplied to motor, different line attachments is selected for different operating modes so that motor no matter rotate forward or reversion when it is equal
It can be powered the switching of power supply, and when system is installed without judging grid phase.
In order to realize that above-mentioned function, this patent adopt the following technical scheme that.
A kind of double grid-connected Switch Three-Phase locking phase frequency conversion all-in-one machines, are made of, major loop is by frequency conversion major loop and control loop
Device A, the first vacuum contactor KM1, the second vacuum contactor KM2, third vacuum contactor KM3, the 4th vacuum contactor KM4,
First voltage Hall sensor T1, second voltage Hall sensor T2 and motor M1 are constituted；Control loop is by the first intermediate relay
Device K01, the second intermediate relay K02, third intermediate relay K03, the 4th intermediate relay K04, PLC and control switch structure
At；
Frequency converter A is that whole system arithmetic core and PLC are communicated by communication bus RS232.When startup, frequency conversion
Device A exports a voltage and frequency is in the startup voltage of slope variation, ensures that motor M1 smoothly completes startup；Motor M1 is run on
After stable state, frequency converter A measures network voltage by first voltage Hall sensor T1 and second voltage Hall sensor T2, to electricity
Net voltage phase angle is calculated, and the frequency of frequency converter output voltage is adjusted by controlling unit, is allowed to Phase Tracking grid phase,
After completing locking phase, then switching is instructed, PLC is sent to by communication bus, the control of subsequent power supply switching is completed by PLC
System；
Vacuum contactor is controll plant, and there are four vacuum contactors altogether for system；The input terminal of first vacuum contactor KM1
Power grid is connected, output end connects the input terminal of frequency converter A；The output of the input terminal connection frequency converter A of second vacuum contactor KM2
UVW, output end is held to connect the input terminal U1V1W1 of motor；The input terminal of third vacuum contactor KM3 is connected to the RST of power grid
End, output end connect the input terminal U1V1W1 of motor M1；The ends RTS of the input terminal connection power grid of 4th vacuum contactor KM4, it is defeated
Outlet is connected to the input terminal U1V1W1 of motor；It is different to complete whole system by the break-make of four vacuum contactors of control by PLC
Switching between operating status；
The R phases and S phases of the input connection power grid of first voltage Hall sensor T1, output end connect the simulation of frequency converter A
Input terminal In1, the S phases and T-phase of the input connection power grid of second voltage Hall sensor T2 are measured, output end connects frequency converter A
Connect frequency converter A to the output of analog input end In2, first voltage Hall sensor T1 and second voltage Hall sensor T2
The ends GND；The main function of the two voltage hall sensors is the line voltage for acquiring power grid, and the voltage collected is transmitted
Input signal to frequency converter A as locking phase program；
Motor M1 is then the control object of system, completes the output of energy；
First intermediate relay K01, the second intermediate relay K02, third intermediate relay K03 and the 4th intermediate relay
K04 is connected on PLC, its on off state is controlled by PLC；In first intermediate relay K01, the second intermediate relay K02, third
Between relay K03 and the 4th intermediate relay K04 be divided into and be not serially connected in the first vacuum contactor KM1, the second vacuum contactor
In the control loop of KM2, third vacuum contactor KM3 and the 4th vacuum contactor KM4, as the transfer of PLC control instructions, directly
Connect driving vacuum contactor action；
PLC receives the instruction that frequency converter A is sent by connection, and it is true to control to control the action of related intermediate relay
The action of empty contactor, and then complete the control to vacuum contactor；
Control switch is switched by the first control switch S1, the second control switch S2, the third controls of control switch S3 and the 4th
S4 is formed, control respectively the automatic mode of startup, manual mode, the startup of system and system stopping.
The phase-lock technique of double grid-connected Switch Three-Phase locking phase frequency conversion all-in-one machines, includes the following steps：
One, the main sequence component of power grid is extracted
First voltage Hall sensor T1 collects grid line voltage URS, second voltage Hall sensor T2 collects
Grid line voltage UTS, the phase voltage u of power grid RST three-phases is found out by (1) (2) (3) formular、us、ut：
Enable va=ur, vb=us, vc=ut, using R-S-T sequences as positive sequence, R-T-S sequences are negative phase-sequence, and electricity is found out with (4) formula
Net positive sequence voltage componentWhereinPlural j is realized with the all-pass filter for shifting to 90 °；
Electrical network negative phase-sequence component is found out with (5) formula
When asymmetrical three-phase,WithBoth greater than zero；CompareWithSize, absolute value it is big be power grid main sequence component；When three-phase symmetrical,WithThere are one being not zero, the item being not zero is the main sequence component of power grid；
Two, main sequence component is coordinately transformed
Remember a, b, c three-phase main sequence componentOrFor Utilize 3-2
Transformation, willIt transforms under two-phase stationary coordinate system, obtains the component of voltage along a phases under rest frame
The perpendicular component of voltage with a
Three, the calculating of grid voltage phase-angle
By the component of voltage under two-phase stationary coordinate systemWithWith the estimated value of grid voltage phase-angleFor rotational voltage
Angle carries out static-rotation transformation and obtains edge as shown in (6) formulaThe component of voltage in directionWith perpendicular toThe electricity in direction
Press component
Through the PI controller operations in frequency converter, the variable quantity of estimation frequency is obtained, which adds mains frequency
Fundamental frequency omegaffUsing integral operation, 2 π of result pair of integral operation is remmed, which is new grid voltage phase-angle
Estimated valueRecycle new grid voltage phase-angle estimated valueFor rotational voltage angle, static-rotation transformation is carried out, is found out
It is new perpendicular toThe component of voltage in directionAnd so on untilIt is zero, pi regulator output is constant, illustrates at this time
The phase angle that locking phase obtainsIdentical with the phase angle of practical rotational voltage, grid voltage phase-angle, which calculates, to be completed；Four, frequency converter output electricity
Press phase calculation
The amount of each phase voltage output of control is the duty ratio given value of each phase in frequency converter A, the output voltage of certain phase and should
The duty ratio given value of phase is directly proportional, and D is given with three-phase duty ratiou、Dv、DwIt is converted by 3-2, obtains two-phase stationary coordinate system
Under equivalent duty ratio DdAnd Dq；
With equivalent duty ratio DdAnd DqAcquire the voltage phase angle θ of frequency converter A outputrAnyway cutting θr∈[0,2π)
Five, the locking phase of frequency converter output voltage and network voltage
The rotation of motor when providing using U-V-W sequences as the positive direction of frequency converter A output voltage, and providing to power with this phase sequence
It is just to turn direction；Corresponding transformation is done in the direction of rotation of power grid main sequence component combination motor M1, obtains the given phase of motor locking phase
Angle θref；
The given phase angle theta of motor locking phaserefSuch as following table of calculating at different conditions：
The calculating of 1 locking phase angle given value of table
By given phase angle thetarefWith frequency converter output voltage phase angle thetarIt is poor to make, and difference is transported by the PI controllers in frequency converter
It calculates, obtains the given frequency variable quantity of frequency converter output voltage, the variable quantity is using the amplitude limit ring that an amplitude is ± 0.5Hz
Section, obtains the given frequency variation delta f of final frequency converter output voltager；Frequency converter original given frequency frIn addition given frequency
Variation delta frIt is exactly that new frequency converter exports given frequencyAnd so on operation, until θrefAnd θrDifference be less than 5 degree,
Then locking phase is completed；
Six, the selection of switching switch
Depending on the selection of switching switch will be in conjunction with the main sequence component situation of power grid and the direction of rotation of motor M1, vacuum contact
The switching law of implement body is as shown in table 2.The input terminal of wherein third vacuum contactor KM3 is connected to the ends power grid RST, output end
It is connected to the input terminal U1V1W1 of motor M1；The input terminal of 4th vacuum contactor KM4 is connected to the ends RTS of power grid, output end
The input terminal U1V1W1 of motor, third vacuum contactor KM3 and the 4th vacuum contactor KM4 are connected to this connection type simultaneously
Connection；
2 switching of table selection rule
| Motor rotates forward | Motor reversal | |
| Network voltage principal component is positive sequence | KM3 is closed | KM4 is closed |
| Network voltage principal component is negative phase-sequence | KM4 is closed | KM3 is closed |
After the completion of locking phase, control instruction is sent to PLC by frequency converter A by communication bus RS232, and PLC controls first
Two intermediate relay K02 cut off the second vacuum contactor KM2, then according to the judgement received as a result, to relay among third
Device K03 or the 4th intermediate relay K04 sending action signals complete third vacuum contactor KM3 or the 4th vacuum contactor KM4
Closed action, complete the switching of power supply.
Compared to the prior art compared with the present invention has following advantage：
1, the abstraction function with power grid main sequence component, when power grid occurs asymmetric, still can to main sequence voltage into
Row separation, and to main sequence component of voltage into horizontal lock.
2, it uses using PI controllers as the control system of core, passes through the phase difference of grid phase and frequency converter output voltage
To adjust the given frequency of frequency converter output, and then the locking phase of realization frequency converter output voltage and network voltage.
3, the wiring of power grid and motor uses biswitch positive-negative sequence parallel way, the direction by power grid main sequence component and electricity
The steering of machine compares, and can be automatically controled the closure of third vacuum contactor KM3 or the 4th vacuum contactor KM4, ensure motor without
By the switching that can complete power supply when rotating forward or inverting.
4, the present invention completes the locking phase of start-up course and its output voltage to network voltage by frequency converter, programmable to patrol
Controller is collected by the action of control intermediate relay to complete the switch control to vacuum contact, frequency conversion when to realize startup
Device gives motor power supply, when stable state, waits for the function that power grid is powered to motor after the completion of locking phase and vacuum contactor switching.
5, the present invention using three-phase Phase Lock Technique to network voltage into horizontal lock, using PI controllers by grid phase and change
Frequency device output voltage phase is locked.Ensure that power supply handoff procedure occur when, the two voltage-phase it is consistent.With it is traditional
All-in-one machine is compared, and The present invention reduces the rush of current that motor and power grid are subject in handoff procedure, improve integrated machine equipment
Safety and reliability.In addition to this, the present invention in the wiring of motor and power grid using positive sequence and the parallel wiring of inverted sequence
Mode, system can judge the vacuum contact that be closed when power supply switches automatically according to voltage phase sequence and motor steering
Device facilitates the installation of system, reduces manual operation.
Description of the drawings
Fig. 1 is the major loop wiring diagram of biswitch three-phase locking phase frequency conversion all-in-one machine.
Fig. 2 is the wiring diagram of PLC control loops.
Fig. 3 is the computing block diagram of grid voltage phase-angle.
Fig. 4 is the phase calculation block diagram of positive-sequence component.
Fig. 5 is the phase calculation block diagram of negative sequence component.
Fig. 6 is the locking phase block diagram of frequency converter output voltage and network voltage.
Specific implementation mode
The present invention is described in detail below in conjunction with the accompanying drawings.
A kind of pair of grid-connected Switch Three-Phase locking phase frequency conversion all-in-one machine is made of major loop (Fig. 1) and control loop (Fig. 2).It leads back
Routing frequency converter A, the first vacuum contactor KM1, the second vacuum contactor KM2, third vacuum contactor KM3, the 4th vacuum connect
Tentaculum KM4, first voltage Hall sensor T1, second voltage Hall sensor T2 and motor M1 are constituted；Control loop is by first
Intermediate relay K01, the second intermediate relay K02, third intermediate relay K03, the 4th intermediate relay K04, PLC and control
Switch is constituted.
It is identical that method when startup and general all-in-one machine start method --- PLC control the first vacuum contactor KM1 and
Second vacuum contactor KM2 is closed, and power grid, frequency converter A and motor M1 three are connected, wait for frequency changer direct current bus voltage
Frequency converter A is started to work when rising to rated value, and the electric voltage frequency and amplitude of output increase in slope, until motor M1 runs shape
State reaches stable state.
Frequency converter output voltage is to that will control the switch of closure when the three-phase voltage locking phase of power grid and switching power supply
Determination method is specific as follows：(after please Summary is changed, corresponding modification the following contents)
Step 1：Extract the main sequence component of power grid
First voltage Hall sensor T1 collects grid line voltage URS, second voltage Hall sensor T2 collects
Grid line voltage UTS, the phase voltage u of power grid RST three-phases is found out by (1) (2) (3) formular、us、ut：
Enable va=ur, vb=us, vc=ut, using R-S-T sequences as positive sequence, R-T-S sequences are negative phase-sequence, and electricity is found out with (4) formula
Net positive sequence voltage componentWhereinPlural j is realized with the all-pass filter for shifting to 90 °.
Electrical network negative phase-sequence component is found out with (5) formula
When asymmetrical three-phase,WithBoth greater than zero；CompareWithSize, absolute value it is big be power grid main sequence component；When three-phase symmetrical,WithThere are one being not zero, the item being not zero is the main sequence component of power grid.
Step 2：Main sequence component is coordinately transformed
3-2 transformation is carried out to the main sequence component in step 1 first, the component under three-phase static coordinate system is transformed to two
Under phase rest frame.
When positive-sequence component is principal component, the formula such as formula (6) of transformation, component vmIndicate the voltage along a phases, component vtTable
Show the voltage perpendicular with a：
When negative sequence component is principal component, the formula such as formula (7) of transformation, componentIndicate the component of voltage along a phases, componentIt indicates and component of voltage perpendicular a：
Step 3：The calculating of grid voltage phase-angle
Use componentAnd componentIt indicates respectively, the component of voltage along a phases under rest frame and the electricity perpendicular to a phases
Press component.
By the component of voltage under two-phase stationary coordinate systemWithWith the estimated value of grid voltage phase-angleFor rotational voltage
Angle carries out static-rotation transformation and obtains edge such as formula (8)The component of voltage in directionWith perpendicular toThe voltage in direction point
Amount
Through the PI controller operations in frequency converter, the variable quantity of estimation frequency is obtained, which adds mains frequency
Fundamental frequency omegaffUsing integral operation, 2 π of result pair of integral operation is remmed, which is new grid voltage phase-angle
Estimated valueRecycle new grid voltage phase-angle estimated valueFor rotational voltage angle, static-rotation transformation is carried out, is asked
Go out it is new perpendicular toThe component of voltage in directionAnd so on untilIt is zero, pi regulator output is constant, illustrates at this time
The phase angle that locking phase obtainsIdentical with the phase angle of practical rotational voltage, grid voltage phase-angle, which calculates, to be completed, computing block diagram such as Fig. 3 institutes
Show.
If estimating obtained phase angleWhen being ahead of actual rotational voltage phase angle,Less than zero, so that pi regulator
Output decline, the mains frequency of estimation declines, and estimated phase angle reduces, and estimated phase angle is moved towards virtual voltage phase angle.
If estimating obtained phase angleWhen lagging behind actual rotational voltage phase angle,More than zero, then it can make pi regulator
Output rise, the mains frequency of estimation rises, and estimated phase angle increases, and estimated phase angle is moved towards virtual voltage phase angle.
When the phase angle of estimation and equal actual rotational voltage phase angle,Equal to zero, pi regulator exports constant, explanation
The phase angle that locking phase at this time obtainsIt is exactly the phase angle of practical rotational voltage, indicates that locking phase is completed.
The control block diagram of above-mentioned algorithm is as shown in Fig. 3.Fig. 4 and Fig. 5 is respectively the phase angle of positive-sequence component and negative sequence component
Computing block diagram.
Step 4：Frequency converter output voltage phase calculation
The amount of each phase voltage output of control is the duty ratio given value of each phase in frequency converter A, the output voltage of certain phase and should
The duty ratio given value of phase is directly proportional, and D is given with three-phase duty ratiou、Dv、DwIt is converted by 3-2, obtains two-phase stationary coordinate system
Under equivalent duty ratio DdAnd Dq：
With equivalent duty ratio DdAnd DqAcquire the voltage phase angle θ of frequency converter A outputrAnyway cutting θr∈[0,2π)
Step 5：The locking phase of frequency converter output voltage and network voltage
Motor M1 when providing using U-V-W sequences as the positive direction of frequency converter A output voltage, and providing to power with this phase sequence
Direction of rotation is just.Corresponding transformation is done in the direction of rotation of power grid main sequence component combination motor, obtains the given phase of motor locking phase
Angle θref。
The given phase angle theta of motor locking phaserefSuch as following table of calculating at different conditions：
The calculating of 1 locking phase angle given value of table
By given phase angle thetarefWith frequency converter output voltage phase angle thetarIt is poor to make, and difference is transported by the PI controllers in frequency converter
It calculates, obtains the given frequency variable quantity of frequency converter output voltage, the variable quantity is using the amplitude limit ring that an amplitude is ± 0.5Hz
Section, obtains the given frequency variation delta f of final frequency converter output voltager.Frequency converter original given frequency frIn addition given frequency
Variation delta frIt is exactly that new frequency converter exports given frequency(such as Fig. 6).And so on operation, until θrefAnd θrDifference
Value is less than 5 degree, then at this moment locking phase is completed.The locking phase block diagram of frequency converter output voltage and network voltage is as shown in Figure 6.
Step 6：Switch the selection of switch
Depending on the selection of switching switch will be in conjunction with the main sequence component situation of power grid and the direction of rotation of motor, vacuum contactor
Specific switching law is as shown in table 2.The input terminal of wherein third vacuum contactor KM3 is connected to the ends power grid RST, and output end connects
It is connected to the input terminal U1V1W1 of motor M1；The input terminal of 4th vacuum contactor KM4 is connected to the ends RTS of power grid, and output end connects
The input terminal U1V1W1 of motor, third vacuum contactor KM3 and the 4th vacuum contactor KM4 are connected to the parallel connection of this connection type.
2 switching of table selection rule
| Motor rotates forward | Motor reversal | |
| Network voltage principal component is positive sequence | KM3 is closed | KM4 is closed |
| Network voltage principal component is negative phase-sequence | KM4 is closed | KM3 is closed |
After the completion of locking phase, control instruction is sent to PLC by frequency converter A by communication bus RS232, and PLC controls first
Two intermediate relay K02 cut off the second vacuum contactor KM2, then according to the judgement received as a result, to relay among third
Device K03 or the 4th intermediate relay K04 sending action signals complete third vacuum contactor KM3 or the 4th vacuum contactor KM4
Closed action, complete the switching of power supply.
Claims (2)
1. a kind of double grid-connected Switch Three-Phase locking phase frequency conversion all-in-one machines, it is characterised in that：It is made of, leads back major loop and control loop
Routing frequency converter A, the first vacuum contactor KM1, the second vacuum contactor KM2, third vacuum contactor KM3, the 4th vacuum connect
Tentaculum KM4, first voltage Hall sensor T1, second voltage Hall sensor T2 and motor M1 are constituted；Control loop is by first
Intermediate relay K01, the second intermediate relay K02, third intermediate relay K03, the 4th intermediate relay K04, PLC and control
Switch is constituted；
Frequency converter A is that whole system arithmetic core and PLC are communicated by communication bus RS232.When startup, frequency converter A is defeated
Go out the startup voltage of a voltage and frequency in slope variation, ensures that motor M1 smoothly completes startup；Motor M1 runs on stable state
Afterwards, frequency converter A measures network voltage by first voltage Hall sensor T1 and second voltage Hall sensor T2, to power grid electricity
Pressure phase angle is calculated, and the frequency of frequency converter output voltage is adjusted by controlling unit, is allowed to Phase Tracking grid phase, is completed
After locking phase, then switching is instructed, PLC is sent to by communication bus, the control of subsequent power supply switching is completed by PLC；
Vacuum contactor is controll plant, and there are four vacuum contactors altogether for system；The input terminal of first vacuum contactor KM1 connects
Power grid, output end connect the input terminal of frequency converter A；The output end of the input terminal connection frequency converter A of second vacuum contactor KM2
UVW, output end connect the input terminal U1V1W1 of motor；The input terminal of third vacuum contactor KM3 is connected to the ends RST of power grid,
Output end connects the input terminal U1V1W1 of motor M1；The ends RTS of the input terminal connection power grid of 4th vacuum contactor KM4, output
End is connected to the input terminal U1V1W1 of motor；PLC completes whole system difference fortune by the break-make of four vacuum contactors of control
Switching between row state；
The R phases and S phases of the input connection power grid of first voltage Hall sensor T1, the analog quantity that output end connects frequency converter A are defeated
Enter and hold In1, the S phases and T-phase of the input connection power grid of second voltage Hall sensor T2, output end connect the simulation of frequency converter A
Measure the output ground connection frequency converter A of input terminal In2, first voltage Hall sensor T1 and second voltage Hall sensor T2
The ends GND；The main function of the two voltage hall sensors is the line voltage for acquiring power grid, and the voltage collected is passed to
Input signal of the frequency converter A as locking phase program；
Motor M1 is then the control object of system, completes the output of energy；
First intermediate relay K01, the second intermediate relay K02, third intermediate relay K03 and the 4th intermediate relay K04
It is connected on PLC, its on off state is controlled by PLC；First intermediate relay K01, the second intermediate relay K02, among third
Relay K03 and the 4th intermediate relay K04 be divided into be not serially connected in the first vacuum contactor KM1, the second vacuum contactor KM2,
In the control loop of third vacuum contactor KM3 and the 4th vacuum contactor KM4, as the transfer of PLC control instructions, directly drive
Dynamic vacuum contactor action；
PLC receives the instruction that frequency converter A is sent by connection, and the action for controlling related intermediate relay connects to control vacuum
The action of tentaculum, and then complete the control to vacuum contactor；
Control switch is by the first control switch S1, the second control switch S2, the third control switch S4 groups of control switch S3 and the 4th
At, control respectively the automatic mode of startup, manual mode, the startup of system and system stopping.
2. the phase-lock technique of double grid-connected Switch Three-Phase locking phase frequency conversion all-in-one machines described in claim 1, it is characterised in that：
Include the following steps：
One, the main sequence component of power grid is extracted
First voltage Hall sensor T1 collects grid line voltage URS, second voltage Hall sensor T2 collects power grid
Line voltage UTS, the phase voltage u of power grid RST three-phases is found out by (1) (2) (3) formular、us、ut：
Enable va=ur, vb=us, vc=ut, using R-S-T sequences as positive sequence, R-T-S sequences are negative phase-sequence, and power grid is being found out just with (4) formula
Sequence voltage componentWhereinPlural j is realized with the all-pass filter for shifting to 90 °；
Electrical network negative phase-sequence component is found out with (5) formula
When asymmetrical three-phase,WithBoth greater than zero；CompareWithSize, absolute value it is big be power grid main sequence component；When three-phase symmetrical,WithThere are one being not zero, the item being not zero is the main sequence component of power grid；
Two, main sequence component is coordinately transformed
Remember a, b, c three-phase main sequence componentOrFor Become using 3-2
It changes, it willIt transforms under two-phase stationary coordinate system, obtains the component of voltage along a phases under rest frameWith
Component of voltage perpendicular a
Three, the calculating of grid voltage phase-angle
By the component of voltage under two-phase stationary coordinate systemWithWith the estimated value of grid voltage phase-angleFor rotational voltage angle,
Static-rotation transformation is carried out, as shown in (6) formula, obtains edgeThe component of voltage in directionWith perpendicular toThe component of voltage in direction
Through the PI controller operations in frequency converter, the variable quantity of estimation frequency is obtained, which adds the fundamental frequency of mains frequency
ωffUsing integral operation, 2 π of result pair of integral operation is remmed, which is new grid voltage phase-angle estimated valueRecycle new grid voltage phase-angle estimated valueFor rotational voltage angle, static-rotation transformation is carried out, finds out new hang down
Directly inThe component of voltage in directionAnd so on untilIt is zero, pi regulator output is constant, illustrates that locking phase at this time obtains
The phase angle arrivedIdentical with the phase angle of practical rotational voltage, grid voltage phase-angle, which calculates, to be completed；
Four, frequency converter output voltage phase calculation
The amount of each phase voltage output of control is the duty ratio given value of each phase, output voltage and the phase of certain phase in frequency converter A
Duty ratio given value is directly proportional, and D is given with three-phase duty ratiou、Dv、DwIt is converted, is obtained under two-phase stationary coordinate system by 3-2
Equivalent duty ratio DdAnd Dq；
With equivalent duty ratio DdAnd DqAcquire the voltage phase angle θ of frequency converter A outputrAnyway cutting θr∈[0,2π)
Five, the locking phase of frequency converter output voltage and network voltage
The rotation side of motor when providing using U-V-W sequences as the positive direction of frequency converter A output voltage, and providing to power with this phase sequence
Xiang Weizheng；Corresponding transformation is done in the direction of rotation of power grid main sequence component combination motor M1, obtains the given phase angle of motor locking phase
θref；
The given phase angle theta of motor locking phaserefSuch as following table of calculating at different conditions：
The calculating of 1 locking phase angle given value of table
By given phase angle thetarefWith frequency converter output voltage phase angle thetarIt is poor to make, and difference is obtained by the PI controller operations in frequency converter
To the given frequency variable quantity of frequency converter output voltage, which obtains using the amplitude limit link that an amplitude is ± 0.5Hz
To the given frequency variation delta f of final frequency converter output voltager；Frequency converter original given frequency frIn addition given frequency changes
Measure Δ frIt is exactly that new frequency converter exports given frequency fr n, and so on operation, until θrefAnd θrDifference be less than 5 degree, then lock
Mutually it is completed；
Six, the selection of switching switch
Depending on the selection of switching switch will be in conjunction with the main sequence component situation of power grid and the direction of rotation of motor M1, vacuum contact utensil
The switching law of body is as shown in table 2.The input terminal of wherein third vacuum contactor KM3 is connected to the ends power grid RST, output end connection
To the input terminal U1V1W1 of motor M1；The input terminal of 4th vacuum contactor KM4 is connected to the ends RTS of power grid, output end connection
To the input terminal U1V1W1 of motor, third vacuum contactor KM3 and the 4th vacuum contactor KM4 are with the parallel connection of this connection type；
2 switching of table selection rule
After the completion of locking phase, control instruction is sent to PLC by frequency converter A by communication bus RS232, and PLC is controlled in second first
Between relay K02 cut off the second vacuum contactor KM2, then according to the judgement received as a result, to third intermediate relay K03
Or the 4th intermediate relay K04 sending action signal, complete closing for third vacuum contactor KM3 or the 4th vacuum contactor KM4
Conjunction acts, and completes the switching of power supply.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN110988478A (en) * | 2019-12-25 | 2020-04-10 | 浙江佳乐科仪股份有限公司 | Phase detection method |
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| CN201594749U (en) * | 2010-01-18 | 2010-09-29 | 东方日立(成都)电控设备有限公司 | Alternating current motor synchronization grid-connected switching device |
| CN105281608A (en) * | 2014-05-26 | 2016-01-27 | 株洲变流技术国家工程研究中心有限公司 | High-voltage variable frequency and power frequency switching method |
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| CN201594749U (en) * | 2010-01-18 | 2010-09-29 | 东方日立(成都)电控设备有限公司 | Alternating current motor synchronization grid-connected switching device |
| CN105281608A (en) * | 2014-05-26 | 2016-01-27 | 株洲变流技术国家工程研究中心有限公司 | High-voltage variable frequency and power frequency switching method |
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| CN110988478A (en) * | 2019-12-25 | 2020-04-10 | 浙江佳乐科仪股份有限公司 | Phase detection method |
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