CN105207261B - Applied to virtual synchronous generator from grid-connected control method and system - Google Patents
Applied to virtual synchronous generator from grid-connected control method and system Download PDFInfo
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Abstract
The present invention relates to a kind of applied to virtual synchronous generator from grid-connected control method and system, pass through the difference according to network voltage and the set end voltage of virtual synchronous generator, electromagnetic equation and uncertain factor item, calculate voltage error, according to the difference and voltage error of network voltage and the set end voltage of virtual synchronous generator, design sliding-mode surface, further according to voltage error and sliding-mode surface, utilize fast terminal sliding mode control algorithm, the difference controlled between the set end voltage and network voltage of virtual synchronous machine reduces, when voltage error is in preset off-grid grid-connected switching error range, off-grid grid-connected switching is carried out to virtual synchronous generator.By above application in virtual synchronous generator from grid-connected control method and system, when carrying out the switching of off-grid grid-connected due to the generator terminal to virtual synchronous machine, basic synchronization between the set end voltage and network voltage of virtual synchronous machine, it not will produce larger dash current, can realize virtual synchronous function seamless switching.
Description
Technical field
The present invention relates to field of electrical control, more particularly to it is a kind of applied to virtual synchronous generator from cutting-in control side
Method and system.
Background technology
With becoming increasingly conspicuous for energy issue of world, distributed generation resource and micro-capacitance sensor are more and more paid close attention to.Micro- electricity
The output of net is all direct current mostly, it is therefore desirable to access power distribution network by gird-connected inverter, but conventional control strategy is matched
Power grid and micro-capacitance sensor safe and stable operation bring challenge.It is called virtually using the microgrid inverter of virtual synchronous generator techniques
Synchronous generator.Virtual synchronous generator (Virtual Synchronous Generator, VSG) needs to operate in two kinds of moulds
Under formula, grid-connected and off-network parallel running.
Different from conventional synchronization generator, micro-capacitance sensor has off-network and grid-connected two kinds of operational modes, needs for both
Pattern and formulate the switchover policy between corresponding off-grid grid-connected, simultaneously/off-network pattern.Such as when off-grid grid-connected switching, work as virtual synchronous
Machine is in after off-grid operation, due to the adjustment effect of voltage and frequency, the amplitude and frequency of working voltage and the reality of power grid
It will appear certain deviation between actual value, with the accumulation of time, can make the width between the voltage of micro-capacitance sensor and network voltage
There is deviation in value and phase, when the frequency and asynchronous phase of the voltage between micro-capacitance sensor voltage and power grid switching may will produce
Micro-capacitance sensor input power grid may be caused larger impact electricity by big grid-connected dash current at the unsuitable grid-connected moment
Stream cannot achieve stable seamless switching control, may result in off-grid grid-connected failure, even result in more serious power grid accident.
Invention content
Based on this, it is necessary to for using cannot achieve the grid-connected stabilization seamless switching problem between off-network, provide one
Kind can make the grid-connected off-grid grid-connected control method and system applied to virtual synchronous generator for stablizing switching between off-network.
A kind of off-grid grid-connected method for handover control applied to virtual synchronous generator includes the following steps：
Establish the mechanical equation and electromagnetic equation of virtual synchronous generator；
Obtain the set end voltage of network voltage and the virtual synchronous generator；
According to the network voltage and the set end voltage of the virtual synchronous generator, the network voltage and institute are obtained
State the difference of the set end voltage of virtual synchronous generator；
According to the difference of the network voltage and the set end voltage of the virtual synchronous generator, the electromagnetic equation
And uncertain factor, calculate voltage error；
According to the difference and the voltage of the network voltage and the set end voltage of the virtual synchronous generator
Error designs sliding-mode surface；
It is controlled described virtual using fast terminal sliding mode control algorithm according to the voltage error and the sliding-mode surface
The difference between the set end voltage of synchronous machine and the network voltage reduces, and calculates corresponding after the difference reduces
Voltage error；
When the voltage error is in preset off-grid grid-connected switching error range, to the virtual synchronous generator into
Row off-grid grid-connected switches.
The present invention also provides a kind of off-grid grid-connected handover control systems applied to virtual synchronous generator, including：
First establishes module, the mechanical equation for establishing virtual synchronous generator and electromagnetic equation；
First acquisition module, the set end voltage for obtaining network voltage and the virtual synchronous generator；
Second acquisition module is obtained for the set end voltage according to the network voltage and the virtual synchronous generator
Take the difference of the network voltage and the set end voltage of the virtual synchronous generator；
Computing module, for the difference according to the network voltage and the set end voltage of the virtual synchronous generator
Value, the electromagnetic equation and uncertain factor calculate voltage error；
Module is designed, for the difference according to the network voltage and the set end voltage of the virtual synchronous generator
And the voltage error, design sliding-mode surface；
Control module, for according to the voltage error and the sliding-mode surface, using fast terminal sliding mode control algorithm,
The difference controlled between the set end voltage and the network voltage of the virtual synchronous machine reduces, and calculates the difference and subtract
Corresponding voltage error after small；
Handover module is used for when the voltage error is in preset off-grid grid-connected switching error range, to described virtual
Synchronous generator carries out off-grid grid-connected switching.
Above application in virtual synchronous generator from grid-connected control method and system, by obtain network voltage with it is virtual
The difference of the set end voltage of synchronous generator, according to the difference of network voltage and the set end voltage of virtual synchronous generator, electromagnetism
Equation and uncertain factor item calculate voltage error, according to the difference of network voltage and the set end voltage of virtual synchronous generator
Value and voltage error design sliding-mode surface, further according to voltage error and sliding-mode surface, using fast terminal sliding mode control algorithm,
The difference controlled between the set end voltage and network voltage of virtual synchronous machine reduces, when voltage error is in preset off-grid grid-connected
When switching error range, off-grid grid-connected switching is carried out to virtual synchronous generator.By above application in virtual synchronous generator
From grid-connected control method and system, when carrying out the switching of off-grid grid-connected due to the generator terminal to virtual synchronous machine, the machine of virtual synchronous machine
Basic synchronization between terminal voltage and network voltage not will produce larger dash current, and virtual synchronous function can be realized without seaming and cutting
It changes.
Description of the drawings
Fig. 1 is a kind of flow chart of the off-grid grid-connected control method applied to virtual synchronous generator of embodiment；
Fig. 2 is virtual synchronous generator control block diagram；
Fig. 3 is a kind of module map of the off-grid grid-connected control system applied to virtual synchronous generator of embodiment.
Specific implementation mode
Referring to Fig. 1, providing a kind of off-grid grid-connected switching control side applied to virtual synchronous generator of embodiment
Method includes the following steps：
S100：Establish the mechanical equation and electromagnetic equation of virtual synchronous generator.
Virtual synchronous generator is controlled using the mechanical equation and electromagnetic equation of virtual synchronous generator, is based on virtual
Synchronous generator gird-connected inverter has the external characteristics as conventional synchronization generator, establishes mechanical equation and electromagnetic equation,
Establish the mathematical model of virtual synchronous generator.Using virtual synchronous generator techniques, using conventional synchronization generator electromagnetism
Equation controls gird-connected inverter, i.e., controls virtual synchronous generator using conventional synchronization generator electromagnetic equation so that empty
Quasi- synchronous generator and conventional synchronization generator external characteristics having the same can improve the distribution hair of the generator containing virtual synchronous
The runnability of electric system and micro-capacitance sensor.
Compared to traditional synchronous generator, power grid has off-network and grid-connected two kinds of operational modes, needs for both
Pattern and formulate the switchover policy between the corresponding off-grid grid-connected of virtual synchronous generator, simultaneously/off-network pattern.Such as off-grid grid-connected switching
When, key is to detect network voltage, the frequency of network voltage and the deviation of phase, and switching when the two is asynchronous may produce
Raw big grid-connected dash current.
By establishing the mechanical equation of the virtual synchronous generator, so that virtual synchronous generator realizes frequency modulation, pressure regulation
And adjusting power.By establishing the mechanical equation and electromagnetic equation of virtual synchronous generator, that is, establish virtual synchronous generator
Mathematical model, simulate the mathematical model of synchronous generator, virtual synchronous generator is modeled to traditional synchronous generator, can be with
The functions such as active adjusting, Reactive-power control, current control and off-grid grid-connected synchronous control, ability are carried out to virtual synchronous generator
Know how the set end voltage of control virtual synchronous generator so that the set end voltage of virtual synchronous generator and network voltage it
Between difference be decreased within the scope of preset off-grid grid-connected switching error in the short period, to realize the machine of virtual synchronous generator
Terminal voltage is synchronous with power grid realization, then carries out off-grid grid-connected switching, not will produce big dash current in this way.
S200：Obtain network voltage and virtual synchronous generator terminal voltage.
The set end voltage of virtual synchronous machine is variable quantity, and network voltage can be used as with reference to amount, the error before the two
When sufficiently small, you can carry out off-grid grid-connected switching.
S300：According to network voltage and the set end voltage of virtual synchronous generator, network voltage and virtual synchronous are obtained
The difference of the set end voltage of generator.
The difference of network voltage and the set end voltage of virtual synchronous generator indicates network voltage and virtual synchronous generator
Set end voltage between there is also deviations, be not carried out synchronization.
S400：According to the difference of network voltage and the set end voltage of virtual synchronous generator, electromagnetic equation and do not know
Because of prime implicant, voltage error is obtained.
In actual application, not only to consider the value of voltage itself, possible external world's uncertain factor also can be to knot
Fruit has an impact, to which uncertain factor be added, it is ensured that result is more acurrate.
S500：According to the difference and voltage error of network voltage and the set end voltage of virtual synchronous generator, design is slided
Die face.
Virtual synchronous set end voltage is designed, the main target of voltage controller design is to realize to make in finite time
Voltage error converges to zero, in order to improve system control performance, using fast terminal sliding mode control strategy, and designs sliding-mode surface,
The switching function of sliding formwork control, that is, sliding-mode surface, what it was characterized is desired system performance, from the point of view of stability angle, one
As take the coefficient to be that just, i.e. difference ratio coefficient generally takes positive value, different sliding-mode surfaces has different convergence characteristics, for example, line
Property sliding-mode surface there is asymptotic convergence, terminal sliding mode face to have finite time convergence control characteristic, so the different sliding-mode surface of selection, dynamic
Response characteristic is different.Even same sliding-mode surface, the selection of difference ratio coefficient is different, convergent time, characteristic
It is different.
S600：According to voltage error and sliding-mode surface virtual synchronous machine is controlled using fast terminal sliding mode control algorithm
Difference between set end voltage and network voltage reduces, and the corresponding voltage error after calculating difference reduction.
Referring to Fig. 2, for the virtual synchronous generator control block diagram of the present embodiment, in practical applications, sliding formwork control is selected
Device processed is controlled, and set end voltage and the network voltage of virtual synchronous machine input sliding mode controller respectively, determine the switching of the two
Function, by fast terminal sliding mode control algorithm, the difference between the set end voltage and network voltage of control control virtual synchronous machine
Value reduces, and the error amount for ensureing between the two can quick smoothly level off to zero.
Sliding formwork control is also variable-structure control, is substantially a kind of special nonlinear Control, and non-linear behavior is control
The discontinuity of system.This control strategy with other controls the difference is that " structure " of system and be not fixed, but can
In dynamic process, purposefully constantly to be changed according to the current state of system, force system according to predetermined " sliding mode "
State trajectory movement.Since sliding mode can be designed and unrelated with image parameter and disturbance, this allows for sliding formwork control
Fixture has the advantages that quick response, corresponding Parameters variation and disturbance are insensitive, simple without system on-line identification, physics realization.
S700：When voltage error is in preset off-grid grid-connected switching error range, virtual synchronous generator is carried out
Off-grid grid-connected switches.
Voltage error goes to zero in Finite-time convergence, illustrates that the set end voltage of virtual synchronous machine can be quick
Change to it is synchronous with network voltage, when the two error is in preset off-grid grid-connected switching error range, you can to virtually generating electricity
Machine carries out the switching of off-grid grid-connected.In the present embodiment, within preset off-grid grid-connected switching error ranging from 10%.
Above application, from grid-connected control method, is sent out by obtaining network voltage with virtual synchronous in virtual synchronous generator
The difference of the set end voltage of motor, according to the difference of network voltage and the set end voltage of virtual synchronous generator, electromagnetic equation with
And uncertain factor item, calculate voltage error, according to the difference of network voltage and the set end voltage of virtual synchronous generator and
Voltage error designs sliding-mode surface, and further according to voltage error and sliding-mode surface, using fast terminal sliding mode control algorithm, control is empty
Difference between the set end voltage and network voltage of quasi- synchronous machine reduces, and is missed when voltage error is in the switching of preset off-grid grid-connected
When poor range, off-grid grid-connected switching is carried out to virtual synchronous generator.By above application in virtual synchronous generator from grid-connected
Control method and system, when carrying out the switching of off-grid grid-connected due to the generator terminal to virtual synchronous machine, the set end voltage of virtual synchronous machine
The basic synchronization between network voltage not will produce larger dash current, can realize virtual synchronous function seamless switching.
The electromagnetic equation of virtual synchronous generator is expressed as in one of the embodiments,：
The difference of network voltage and the set end voltage of virtual synchronous generator is expressed as：
eu=ugabc-uabc。
The specific formula for calculation of voltage error is：
In formula, L is the synchronous inductance of virtual synchronous generator, and R is the synchronization resistance of virtual synchronous generator, eabc、uabc
And iabcRespectively generator terminal potential, voltage and the electric current of virtual synchronous generator, euFor network voltage ugabcWith virtual synchronous
The set end voltage u of generatorabcDifference,For voltage error, ρuFor uncertain factor.
The stability of system is had an impact since there are possible factors in system, to which virtual synchronous power generation can be influenced
The set end voltage of machine is synchronous with network voltage, in the same of the set end voltage and network voltage for controlling virtual synchronous generator
It during step, not only needs to consider the difference between the set end voltage and network voltage of virtual synchronous generator, and needs to examine
Consider other influences factor, increases uncertain factor ρu, to indicate influence factor that may be present in a practical situation, by prior
Many experiments can obtain the ρu, i.e. ρuFor the known constant being worth to according to experience.Since some may present in system
Disturbance, the difference between the set end voltage and network voltage of virtual synchronous generator had both been considered, it is further contemplated that uncertain factor ρu,
It can be realized when being controlled system using sliding formwork control and more be accurately controlled effect.
The specific formula of sliding-mode surface design is in one of the embodiments,：
In formula, SuFor sliding-mode surface, k is difference ratio coefficient.
The mechanical equation of virtual synchronous generator is expressed as in one of the embodiments,：
TeIt is expressed as：
Te=Pe/ ω=(eaia+ebib+ecic)/ω；
In formula, J is the inertia time constant of virtual synchronous generator, and ω is the angular speed of virtual synchronous generator, ω0For
Synchronized angular speed, Tm、TeAnd TdThe respectively machine torque of virtual synchronous generator, electromagnetic torque and damping torque,
D is damped coefficient, PeFor the electromagnetic power of virtual synchronous generator output, ea、ebAnd ecRespectively virtual synchronous generator
The generator terminal potential of A phases, B phases and C phases, ia、ibAnd icThe respectively generator terminal of the A phases, B phases and C phases of virtual synchronous generator
Electric current.By establishing the mechanical equation of the virtual synchronous generator so that virtual synchronous generator realize frequency modulation, pressure regulation and
Adjusting power.I.e. by simulating the mathematical model of synchronous generator, virtual synchronous generator is modeled to traditional synchronous generator, can
Realize the adjusting of the parameters such as adjusting and the voltage of power, it is synchronous with power grid realization.
Gird-connected inverter is controlled using the mechanical equation of conventional synchronization generator so that gird-connected inverter in mechanism and
It can compare favourably with synchronous generator in external characteristics.Due to the presence of J, ground gird-connected inverter is made to have during frequency disturbance
Inertia, and due to the presence of D so that inverter type generates electricity by way of merging two or more grid systems device there is also the ability of resistance system power concussion, this two
A variable has important improvement result to the runnability of power grid.
Referring to Fig. 3, a kind of off-grid grid-connected handover control system applied to virtual synchronous generator, including：
First establishes mould 100, the mechanical equation for establishing virtual synchronous generator and electromagnetic equation.
Virtual synchronous generator is controlled using the mechanical equation and electromagnetic equation of virtual synchronous generator, is based on virtual
Synchronous generator gird-connected inverter has the external characteristics as conventional synchronization generator, establishes mechanical equation and electromagnetic equation,
Establish the mathematical model of virtual synchronous generator.Using virtual synchronous generator techniques, using conventional synchronization generator electromagnetism
Equation controls gird-connected inverter, i.e., controls virtual synchronous generator using conventional synchronization generator electromagnetic equation so that empty
Quasi- synchronous generator and conventional synchronization generator external characteristics having the same can improve the distribution hair of the generator containing virtual synchronous
The runnability of electric system and micro-capacitance sensor.
Compared to traditional synchronous generator, power grid has off-network and grid-connected two kinds of operational modes, needs for both
Pattern and formulate the switchover policy between the corresponding off-grid grid-connected of virtual synchronous generator, simultaneously/off-network pattern.Such as off-grid grid-connected switching
When, key is to detect network voltage, the frequency of network voltage and the deviation of phase, and switching when the two is asynchronous may produce
Raw big grid-connected dash current.
By establishing the mechanical equation of the virtual synchronous generator, so that virtual synchronous generator realizes frequency modulation, pressure regulation
And adjusting power.By establishing the mechanical equation and electromagnetic equation of virtual synchronous generator, that is, establish virtual synchronous generator
Mathematical model, simulate the mathematical model of synchronous generator, virtual synchronous generator is modeled to traditional synchronous generator, can be with
The functions such as active adjusting, Reactive-power control, current control and off-grid grid-connected synchronous control, ability are carried out to virtual synchronous generator
Know how the set end voltage of control virtual synchronous generator so that the set end voltage of virtual synchronous generator and network voltage it
Between difference be decreased within the scope of preset off-grid grid-connected switching error in the short period, to realize the machine of virtual synchronous generator
Terminal voltage is synchronous with power grid realization, then carries out off-grid grid-connected switching, not will produce big dash current in this way.
First acquisition module 200, for obtaining network voltage and virtual synchronous generator terminal voltage.
The set end voltage of virtual synchronous machine is variable quantity, and network voltage can be used as with reference to amount, the error before the two
When sufficiently small, you can carry out off-grid grid-connected switching.
Second acquisition module 300 obtains power grid for the set end voltage according to network voltage and virtual synchronous generator
The difference of voltage and the set end voltage of virtual synchronous generator.
The difference of network voltage and the set end voltage of virtual synchronous generator indicates network voltage and virtual synchronous generator
Set end voltage between there is also deviations, be not carried out synchronization.
Computing module 400, for the difference according to network voltage and the set end voltage of virtual synchronous generator, electromagnetic equation
And uncertain factor, calculate voltage error.
In actual application, not only to consider the value of voltage itself, possible external world's uncertain factor also can be to knot
Fruit has an impact, to which uncertain factor item be added, it is ensured that result is more acurrate.
Module 500 is designed, for the difference and voltage according to network voltage and the set end voltage of virtual synchronous generator
Error designs sliding-mode surface.
Virtual synchronous set end voltage is designed, the main target of voltage controller design is to realize to make in finite time
Voltage error converges to zero, in order to improve system control performance, using fast terminal sliding mode control strategy, and designs sliding-mode surface,
The switching function of sliding formwork control, that is, sliding-mode surface, what it was characterized is desired system performance, from the point of view of stability angle, one
As take the coefficient to be that just, i.e. difference ratio coefficient generally takes positive value, different sliding-mode surfaces has different convergence characteristics, for example, line
Property sliding-mode surface there is asymptotic convergence, terminal sliding mode face to have finite time convergence control characteristic, so the different sliding-mode surface of selection, dynamic
Response characteristic is different.Even same sliding-mode surface, the selection of difference ratio coefficient is different, convergent time, characteristic
It is different.
Control module 600, for according to voltage error and sliding-mode surface, utilizing fast terminal sliding mode control algorithm, control
Difference between the set end voltage and network voltage of virtual synchronous machine reduces, and the corresponding voltage after calculating difference reduction misses
Difference.
In practical applications, fast terminal sliding mode controller is selected to be controlled, set end voltage and the electricity of virtual synchronous machine
Net voltage inputs sliding mode controller respectively, determines the switching function of the two, passes through fast terminal sliding mode control algorithm, control control
Difference between the set end voltage and network voltage of virtual synchronous machine reduces, and ensures that error amount between the two can be quick smoothly
Level off to zero.
Sliding formwork control is also variable-structure control, is substantially a kind of special nonlinear Control, and non-linear behavior is control
The discontinuity of system.This control strategy with other controls the difference is that " structure " of system and be not fixed, but can
In dynamic process, purposefully constantly to be changed according to the current state of system, force system according to predetermined " sliding mode "
State trajectory movement.Since sliding mode can be designed and unrelated with image parameter and disturbance, this allows for sliding formwork control
Fixture has the advantages that quick response, corresponding Parameters variation and disturbance are insensitive, simple without system on-line identification, physics realization.
Handover module 700 is used for when voltage error is in preset off-grid grid-connected switching error range, to virtual synchronous
Generator carries out off-grid grid-connected switching.
Voltage error goes to zero in Finite-time convergence, illustrates that the set end voltage of virtual synchronous machine can be quick
Change to it is synchronous with network voltage, when the two error is in preset off-grid grid-connected switching error range, you can to virtually generating electricity
Machine carries out the switching of off-grid grid-connected.In the present embodiment, within preset off-grid grid-connected switching error ranging from 10%.
Above application, from grid-connection control system, is sent out by obtaining network voltage with virtual synchronous in virtual synchronous generator
The difference of the set end voltage of motor, according to the difference of network voltage and the set end voltage of virtual synchronous generator, electromagnetic equation with
And uncertain factor item, calculate voltage error, according to the difference of network voltage and the set end voltage of virtual synchronous generator and
Voltage error designs sliding-mode surface, and further according to voltage error and sliding-mode surface, using fast terminal sliding mode control algorithm, control is empty
Difference between the set end voltage and network voltage of quasi- synchronous machine reduces, and is missed when voltage error is in the switching of preset off-grid grid-connected
When poor range, off-grid grid-connected switching is carried out to virtual synchronous generator.By above application in virtual synchronous generator from grid-connected
Control method and system, when carrying out the switching of off-grid grid-connected due to the generator terminal to virtual synchronous machine, the set end voltage of virtual synchronous machine
The basic synchronization between network voltage not will produce larger dash current, can realize virtual synchronous function seamless switching.
The electromagnetic equation of virtual synchronous generator is expressed as in one of the embodiments,：
The difference of network voltage and the set end voltage of virtual synchronous generator is expressed as：
eu=ugabc-uabc；
The specific formula for calculation of voltage error is：
In formula, L is the synchronous inductance of virtual synchronous generator, and R is the synchronization resistance of virtual synchronous generator, eabc、uabc
And iabcRespectively generator terminal potential, voltage and the electric current of virtual synchronous generator, euFor network voltage ugabcWith virtual synchronous
The set end voltage u of generatorabcDifference,For voltage error, ρuFor uncertain factor.
The stability of system is had an impact since there are possible factors in system, to which virtual synchronous power generation can be influenced
The set end voltage of machine is synchronous with network voltage, in the same of the set end voltage and network voltage for controlling virtual synchronous generator
It during step, not only needs to consider the difference between the set end voltage and network voltage of virtual synchronous generator, and needs to examine
Consider other influences factor, increases uncertain factor ρu, to indicate influence factor that may be present in a practical situation, by prior
Many experiments can obtain the ρu, i.e. ρuFor the known constant being worth to according to experience.Since some may present in system
Disturbance, the difference between the set end voltage and network voltage of virtual synchronous generator had both been considered, it is further contemplated that uncertain factor ρu,
It can be realized when being controlled system using sliding formwork control and more be accurately controlled effect.
The specific formula of sliding-mode surface design is in one of the embodiments,：
In formula, SuFor sliding-mode surface, k is difference ratio coefficient.
The mechanical equation of virtual synchronous generator is expressed as in one of the embodiments,：
TeIt is expressed as：
Te=Pe/ ω=(eaia+ebib+ecic)/ω；
In formula, the J is the inertia time constant of the virtual synchronous generator, and the ω generates electricity for the virtual synchronous
The angular speed of machine, the ω0For synchronized angular speed, the Tm, the TeAnd the TdThe respectively described virtual synchronous hair
Machine torque, electromagnetic torque and the damping torque of motor, the D are damped coefficient, PeFor the output of virtual synchronous generator
Electromagnetic power, ea、ebAnd ecRespectively the A phases, B phases of virtual synchronous generator and the generator terminal potential of C phases, ia、ibAnd ic
Respectively the A phases, B phases of virtual synchronous generator and the generator terminal electric current of C phases.
By establishing the mechanical equation of the virtual synchronous generator, so that virtual synchronous generator realizes frequency modulation, pressure regulation
And adjusting power.I.e. by simulating the mathematical model of synchronous generator, virtual synchronous generator is modeled to traditional synchronous generator
Machine, it can be achieved that the parameters such as the adjusting of power and voltage adjusting, it is synchronous with power grid realization.
Gird-connected inverter is controlled using conventional synchronization generator mechanical equation so that gird-connected inverter is in mechanism and outer
It can compare favourably with synchronous generator in characteristic.Due to the presence of J, ground gird-connected inverter is set to have during frequency disturbance used
Property, and due to the presence of D so that inverter type generates electricity by way of merging two or more grid systems device there is also the ability of resistance system power concussion, the two
Variable has important improvement result to the runnability of power grid.
Each technical characteristic of above example can be combined arbitrarily, to keep description succinct, not to above-described embodiment
In each technical characteristic it is all possible combination be all described, as long as however, the combination of these technical characteristics be not present lance
Shield is all considered to be the range of this specification record.
Only several embodiments of the present invention are expressed for above example, the description thereof is more specific and detailed, but can not
Therefore it is construed as limiting the scope of the patent.It should be pointed out that for those of ordinary skill in the art,
Under the premise of not departing from present inventive concept, various modifications and improvements can be made, these are all within the scope of protection of the present invention.
Therefore, the protection domain of patent of the present invention should be determined by the appended claims.
Claims (6)
1. a kind of off-grid grid-connected method for handover control applied to virtual synchronous generator, which is characterized in that include the following steps：
Establish the mechanical equation and electromagnetic equation of virtual synchronous generator；
Obtain the set end voltage of network voltage and the virtual synchronous generator；
According to the network voltage and the set end voltage of the virtual synchronous generator, the network voltage and the void are obtained
The difference of the set end voltage of quasi- synchronous generator；
According to the difference of the network voltage and the set end voltage of the virtual synchronous generator, the electromagnetic equation and
Uncertain factor calculates voltage error, wherein the uncertain factor is obtained ahead of time according to experiment；
The difference with the set end voltage of the virtual synchronous generator and the voltage error according to the network voltage,
Design sliding-mode surface；
According to the voltage error and the sliding-mode surface virtual synchronous is controlled using fast terminal sliding mode control algorithm
The difference between the set end voltage of machine and the network voltage reduces, and calculates the corresponding voltage after the difference reduces
Error；
When the voltage error is in preset off-grid grid-connected switching error range, to the virtual synchronous generator carry out from/
Grid-connected switching；
The electromagnetic equation of the virtual synchronous generator is expressed as：
The difference of the network voltage and the set end voltage of the virtual synchronous generator is expressed as：
eu=ugabc-uabc；
The specific formula for calculation of the voltage error is：
In formula, the L is the synchronous inductance of the virtual synchronous generator, and the R is the synchronization of the virtual synchronous generator
Resistance, the eabc, the uabcAnd the iabcGenerator terminal potential, voltage and the electricity of the respectively described virtual synchronous generator
Stream, the euFor the network voltage ugabcWith the set end voltage u of the virtual synchronous generatorabcDifference, it is describedFor institute
State voltage error, the ρuFor the uncertain factor；
The specific formula of sliding-mode surface design is：
In formula, the SuFor the sliding-mode surface, the k is difference ratio coefficient.
2. the off-grid grid-connected method for handover control according to claim 1 applied to virtual synchronous generator, feature exists
In the mechanical equation of the virtual synchronous generator is expressed as：
The TeIt is expressed as：
Te=Pe/ ω=(eaia+ebib+ecic)/ω；
In formula, the J is the inertia time constant of the virtual synchronous generator, and the ω is the virtual synchronous generator
Angular speed, the ω0For synchronized angular speed, the Tm, the TeAnd the TdThe respectively described virtual synchronous generator
Machine torque, electromagnetic torque and damping torque, the D be damped coefficient, the PeIt is defeated for the virtual synchronous generator
The electromagnetic power gone out, the ea, the ebAnd the ecThe A phases of the respectively described virtual synchronous generator, B phases and C phases
Generator terminal potential, the ia, the ibAnd the icA phases, the generator terminal of B phases and C phases of the respectively described virtual synchronous generator
Electric current；
By establishing the mechanical equation of the virtual synchronous generator, so that the virtual synchronous generator realizes frequency modulation, pressure regulation
And adjusting power.
3. the off-grid grid-connected method for handover control according to claim 1 applied to virtual synchronous generator, feature exists
In within the preset off-grid grid-connected switching error ranging from 10%.
4. a kind of off-grid grid-connected handover control system applied to virtual synchronous generator, which is characterized in that including：
First establishes module, the mechanical equation for establishing virtual synchronous generator and electromagnetic equation；
First acquisition module, the set end voltage for obtaining network voltage and the virtual synchronous generator；
Second acquisition module obtains institute for the set end voltage according to the network voltage and the virtual synchronous generator
State the difference of network voltage and the set end voltage of the virtual synchronous generator；
Computing module, for the difference according to the network voltage and the set end voltage of the virtual synchronous generator, institute
Electromagnetic equation and uncertain factor are stated, calculates voltage error, wherein the uncertain factor is obtained ahead of time according to experiment；
Design module, for according to the difference of the network voltage and the set end voltage of the virtual synchronous generator and
The voltage error designs sliding-mode surface；
Control module, for according to the voltage error and the sliding-mode surface, utilizing fast terminal sliding mode control algorithm, control
The difference between the set end voltage and the network voltage of the virtual synchronous machine reduces, and calculates after the difference reduces
Corresponding voltage error；
Handover module is used for when the voltage error is in preset off-grid grid-connected switching error range, to the virtual synchronous
Generator carries out off-grid grid-connected switching；
The electromagnetic equation of the virtual synchronous generator is expressed as：
The difference of the network voltage and the set end voltage of the virtual synchronous generator is expressed as：
eu=ugabc-uabc；
The specific formula for calculation of the voltage error is：
In formula, the L is the synchronous inductance of the virtual synchronous generator, and the R is the synchronization of the virtual synchronous generator
Resistance, the eabc, the uabcAnd the iabcGenerator terminal potential, voltage and the electricity of the respectively described virtual synchronous generator
Stream, the euFor the network voltage ugabcWith the set end voltage u of the virtual synchronous generatorabcDifference, it is describedFor institute
State voltage error, the ρuFor the uncertain factor；
The specific formula of sliding-mode surface design is：
In formula, the SuFor the sliding-mode surface, the k is difference ratio coefficient.
5. the off-grid grid-connected handover control system according to claim 4 applied to virtual synchronous generator, feature exists
In the mechanical equation of the virtual synchronous generator is expressed as：
The TeIt is expressed as：
Te=Pe/ ω=(eaia+ebib+ecic)/ω；
In formula, the J is the inertia time constant of the virtual synchronous generator, and the ω is the virtual synchronous generator
Angular speed, the ω0For synchronized angular speed, the Tm, the TeAnd the TdThe respectively described virtual synchronous generator
Machine torque, electromagnetic torque and damping torque, the D be damped coefficient, the PeIt is defeated for the virtual synchronous generator
The electromagnetic power gone out, the ea, the ebAnd the ecThe A phases of the respectively described virtual synchronous generator, B phases and C phases
Generator terminal potential, the ia, the ibAnd the icA phases, the generator terminal of B phases and C phases of the respectively described virtual synchronous generator
Electric current；
By establishing the mechanical equation of the virtual synchronous generator, so that the virtual synchronous generator realizes frequency modulation, pressure regulation
And adjusting power.
6. the off-grid grid-connected handover control system according to claim 4 applied to virtual synchronous generator, feature exists
In within the preset off-grid grid-connected switching error ranging from 10%.
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