CN105207261A - Off-grid and grid-connection control method and system for virtual synchronous generator - Google Patents

Off-grid and grid-connection control method and system for virtual synchronous generator Download PDF

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CN105207261A
CN105207261A CN201510633570.9A CN201510633570A CN105207261A CN 105207261 A CN105207261 A CN 105207261A CN 201510633570 A CN201510633570 A CN 201510633570A CN 105207261 A CN105207261 A CN 105207261A
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virtual synchronous
synchronous generator
voltage
grid
difference
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CN105207261B (en
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唐酿
盛超
孙闻
金杨
翁洪杰
肖湘宁
袁敞
陈锐
张俊峰
朱良合
罗运松
张毅超
吴晓宇
刘正富
安然然
赵艳军
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Electric Power Research Institute of Guangdong Power Grid Co Ltd
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Electric Power Research Institute of Guangdong Power Grid Co Ltd
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Abstract

The invention relates to an off-grid and grid-connection control method and system for a virtual synchronous generator. A voltage error is calculated through a difference value between the grid voltage and the generator terminal voltage of the virtual synchronous generator, an electromagnetic equation and uncertain factor items; a sliding mode surface is designed according to the difference value between the grid voltage and the generator terminal voltage of the virtual synchronous generator and the voltage error; the difference value between the generator terminal voltage of the virtual synchronous generator and the grid voltage is controlled to be decreased according to the voltage error and the sliding mode surface through a fast terminal sliding mode control algorithm; when the voltage error is within a preset off-grid and grid-connection switching error range, off-grid and grid-connection switching is performed on the virtual synchronous generator. According to the off-grid and grid-connection control method and system for the virtual synchronous generator, due to the fact that when off-grid and grid-connection switching is performed on a generator terminal of the virtual synchronous generator, the generator terminal voltage of the virtual synchronous generator and the grid voltage are basically synchronous and a large impact current cannot be generated, the virtual synchronous generator can achieve seamless switching.

Description

Be applied to virtual synchronous generator from grid-connected control method and system
Technical field
The present invention relates to field of electrical control, particularly a kind of be applied to virtual synchronous generator from grid-connected control method and system.
Background technology
Along with becoming increasingly conspicuous of energy issue of world, distributed power source and micro-capacitance sensor are more and more paid close attention to.The output of micro-capacitance sensor is all direct current mostly, therefore need to access power distribution network by combining inverter, but the control strategy of routine brings challenge to power distribution network and micro-capacitance sensor safe and stable operation.The microgrid inverter of virtual synchronous generator techniques is adopted to be called virtual synchronous generator.Virtual synchronous generator (VirtualSynchronousGenerator, VSG) needs to run in both modes, grid-connected and from net parallel running.
Be different from conventional synchronization generator, micro-capacitance sensor has from net and grid-connected two kinds of operational modes, need these two kinds of patterns are formulated corresponding from/grid-connected and/from the switchover policy between net pattern.Time such as from/grid-connected switching, when virtual synchronous machine is in from after network operation, due to the regulating action of voltage and frequency, the amplitude of its working voltage and there will be certain deviation between frequency and the actual value of electrical network, along with the accumulation of time, the amplitude between the voltage of micro-capacitance sensor and line voltage and phase place can be made to occur deviation, switch when the frequency of the voltage between micro-capacitance sensor voltage and electrical network is asynchronous with phase place and may produce large grid-connected impulse current, namely in the unaccommodated grid-connected moment, micro-capacitance sensor is dropped into electrical network and may cause larger impulse current, stable seamless switching cannot be realized control, may cause from/grid-connected failure, even cause more serious power grid accident.
Summary of the invention
Based on this, be necessary for utilize cannot realize grid-connected and from the stable seamless switching problem between netting, provide a kind of can make grid-connected and from the stable switching between netting be applied to virtual synchronous generator from/grid-connected control method and system.
Be applied to virtual synchronous generator from/grid-connected a method for handover control, comprise the following steps:
Set up mechanical equation and the electromagnetic equation of virtual synchronous generator;
Obtain the set end voltage of line voltage and described virtual synchronous generator;
According to the set end voltage of described line voltage and described virtual synchronous generator, obtain the difference of the set end voltage of described line voltage and described virtual synchronous generator;
According to the described difference of the set end voltage of described line voltage and described virtual synchronous generator, described electromagnetic equation and uncertain factor, calculating voltage error;
According to described difference and the described voltage error of the set end voltage of described line voltage and described virtual synchronous generator, design sliding-mode surface;
According to described voltage error and described sliding-mode surface, utilize fast terminal sliding mode control algorithm, the described difference controlled between the set end voltage of described virtual synchronous machine and described line voltage reduces, and calculates the corresponding voltage error after the reduction of described difference;
When described voltage error be in default from/grid-connected switching error scope time, described virtual synchronous generator is carried out from/grid-connected switching.
The present invention also provide a kind of be applied to virtual synchronous generator from/grid-connected handover control system, comprising:
First sets up module, for setting up mechanical equation and the electromagnetic equation of virtual synchronous generator;
First acquisition module, for obtaining the set end voltage of line voltage and described virtual synchronous generator;
Second acquisition module, for the set end voltage according to described line voltage and described virtual synchronous generator, obtains the difference of the set end voltage of described line voltage and described virtual synchronous generator;
Computing module, for the described difference of the set end voltage according to described line voltage and described virtual synchronous generator, described electromagnetic equation and uncertain factor, calculating voltage error;
Design module, for described difference and the described voltage error of the set end voltage according to described line voltage and described virtual synchronous generator, design sliding-mode surface;
Control module, for according to described voltage error and described sliding-mode surface, utilize fast terminal sliding mode control algorithm, the described difference controlled between the set end voltage of described virtual synchronous machine and described line voltage reduces, and calculates the corresponding voltage error after the reduction of described difference;
Handover module, for be in when described voltage error default from/grid-connected switching error scope time, described virtual synchronous generator is carried out from/grid-connected switching.
Above-mentioned be applied to virtual synchronous generator from grid-connected control method and system, by obtaining the difference of the set end voltage of line voltage and virtual synchronous generator, according to the difference of the set end voltage of line voltage and virtual synchronous generator, electromagnetic equation and uncertain factor item, calculating voltage error, according to difference and the voltage error of the set end voltage of line voltage and virtual synchronous generator, design sliding-mode surface, again according to voltage error and sliding-mode surface, utilize fast terminal sliding mode control algorithm, the difference controlled between the set end voltage of virtual synchronous machine and line voltage reduces, when voltage error be in default from/grid-connected switching error scope time, virtual synchronous generator is carried out from/grid-connected switching.By above-mentioned be applied to virtual synchronous generator from grid-connected control method and system, during owing to carrying out the machine end of virtual synchronous machine from/grid-connected switching, basic synchronization between the set end voltage of virtual synchronous machine and line voltage, larger impulse current can not be produced, virtual synchronous function seamless switching can be realized.
Accompanying drawing explanation
Fig. 1 is a kind of flow chart from/grid-connected control method being applied to virtual synchronous generator of execution mode;
Fig. 2 is virtual synchronous generator control block diagram;
Fig. 3 is a kind of module map from/grid-connection control system being applied to virtual synchronous generator of execution mode.
Embodiment
Refer to Fig. 1, provide a kind of execution mode be applied to virtual synchronous generator from/grid-connected method for handover control, comprise the following steps:
S100: mechanical equation and the electromagnetic equation of setting up virtual synchronous generator.
Utilize the mechanical equation of virtual synchronous generator and electromagnetic equation to control virtual synchronous generator,, based on virtual synchronous generator connecting in parallel with system inverter, there is the external characteristic the same with conventional synchronization generator, set up mechanical equation and electromagnetic equation, namely set up the Mathematical Modeling of virtual synchronous generator.Utilize virtual synchronous generator techniques, conventional synchronization generator electromagnetic equation is adopted to control combining inverter, namely conventional synchronization generator electromagnetic equation is adopted to control virtual synchronous generator, make virtual synchronous generator have identical external characteristic with conventional synchronization generator, the runnability of distribution electricity generation system containing virtual synchronous generator and micro-capacitance sensor can be improved.
Compared to traditional synchronous generator, electrical network has from net and grid-connected two kinds of operational modes, need these two kinds of patterns are formulated virtual synchronous generator corresponding from/grid-connected and/from the switchover policy between net pattern.Time such as from/grid-connected switching, key is the frequency of detection of grid voltage, line voltage and the deviation of phase place, switches may produce large grid-connected impulse current when both are asynchronous.
By setting up the mechanical equation of described virtual synchronous generator, realize frequency modulation, pressure regulation and adjusting power to make virtual synchronous generator.By setting up mechanical equation and the electromagnetic equation of virtual synchronous generator, namely the Mathematical Modeling of virtual synchronous generator is established, the Mathematical Modeling of simulation synchronous generator, virtual synchronous generator is modeled to traditional synchronous generator, meritorious adjustment can be carried out to virtual synchronous generator, Reactive-power control, Current Control and from functions such as/grid-connected Synchronization Control, just can know the set end voltage how controlling virtual synchronous generator, default within the scope of/grid-connected switching error to make the difference between the set end voltage of virtual synchronous generator and line voltage be decreased in the short period, realize synchronous with the set end voltage realizing virtual synchronous generator with electrical network, carry out from/grid-connected switching again, large impulse current can not be produced like this.
S200: obtain line voltage and virtual synchronous generator terminal voltage.
The set end voltage of virtual synchronous machine is variable quantity, and line voltage can as with reference to amount, and enough hour of the error before both, can carry out from/grid-connected switching.
S300: according to the set end voltage of line voltage and virtual synchronous generator, obtains the difference of the set end voltage of line voltage and virtual synchronous generator.
Also there is deviation between the set end voltage that the difference of the set end voltage of line voltage and virtual synchronous generator represents line voltage and virtual synchronous generator, do not realize synchronous.
S400: according to the difference of the set end voltage of line voltage and virtual synchronous generator, electromagnetic equation and uncertain factor item, obtain voltage error.
In actual application, not only to consider the value of voltage itself, extraneous uncertain factor also may can have an impact to result, thus add uncertain factor, guarantee that result is more accurate.
S500: according to difference and the voltage error of the set end voltage of line voltage and virtual synchronous generator, design sliding-mode surface.
Virtual synchronous set end voltage is designed, the main target of voltage controller design realizes making voltage error converge to zero at finite time, in order to improve system control performance, adopt fast terminal sliding mode control strategy, and design sliding-mode surface, the switching function that sliding formwork controls, namely sliding-mode surface, what it characterized is the system performance expected, from stability angle, generally getting coefficient is just, namely difference proportionality coefficient generally get on the occasion of, different sliding-mode surfaces has different convergence characteristics, such as, linear sliding mode mask has asymptotic convergence, terminal sliding mode mask has finite time convergence control characteristic, so select different sliding-mode surfaces, dynamic response characteristic is different.Even same sliding-mode surface, difference proportionality coefficient is selected different, and the time of convergence, characteristic are also different.
S600: according to voltage error and sliding-mode surface, utilizes fast terminal sliding mode control algorithm, and the difference controlled between the set end voltage of virtual synchronous machine and line voltage reduces, and the corresponding voltage error after calculated difference reduction.
Refer to Fig. 2, for the virtual synchronous generator control block diagram of the present embodiment, in actual applications, sliding mode controller is selected to control, set end voltage and the line voltage of virtual synchronous machine input sliding mode controller respectively, determine both switching functions, by fast terminal sliding mode control algorithm, the difference controlled between the set end voltage of virtual synchronous machine and line voltage reduces, and ensures that error amount between the two can quick smoothly level off to zero.
Sliding formwork controls also to be variable-structure control, is the special nonlinear Control of a class in essence, and non-linear behavior is the discontinuity of control.This control strategy and other differences controlled are that " structure " of system does not fix, but can in dynamic process, and the state current according to system on purpose constantly changes, and force system according to the state trajectory motion of predetermined " sliding mode ".Can carry out designing due to sliding mode and have nothing to do with image parameter and disturbance, this just makes sliding formwork control to have quick response, corresponding Parameters variation and disturbance is insensitive, without the need to advantages such as system on-line identification, physics realization are simple.
S700: when voltage error be in default from/grid-connected switching error scope time, virtual synchronous generator is carried out from/grid-connected switching.
Voltage error is at Finite-time convergence, and go to zero, illustrate virtual synchronous machine set end voltage can Rapid Variable Design to synchronous with line voltage, when both errors be in default from/grid-connected switching error scope time, can carry out from/grid-connected switching virtual synchronous generator.In the present embodiment, preset from/grid-connected switching error scope be within 10%.
Above-mentioned be applied to virtual synchronous generator from grid-connected control method, by obtaining the difference of the set end voltage of line voltage and virtual synchronous generator, according to the difference of the set end voltage of line voltage and virtual synchronous generator, electromagnetic equation and uncertain factor item, calculating voltage error, according to difference and the voltage error of the set end voltage of line voltage and virtual synchronous generator, design sliding-mode surface, again according to voltage error and sliding-mode surface, utilize fast terminal sliding mode control algorithm, the difference controlled between the set end voltage of virtual synchronous machine and line voltage reduces, when voltage error be in default from/grid-connected switching error scope time, virtual synchronous generator is carried out from/grid-connected switching.By above-mentioned be applied to virtual synchronous generator from grid-connected control method and system, during owing to carrying out the machine end of virtual synchronous machine from/grid-connected switching, basic synchronization between the set end voltage of virtual synchronous machine and line voltage, larger impulse current can not be produced, virtual synchronous function seamless switching can be realized.
Wherein in an embodiment, the electromagnetic equation of virtual synchronous generator is expressed as:
L di a b c d t = e a b c - u a b c - Ri a b c .
The difference of the set end voltage of line voltage and virtual synchronous generator is expressed as:
e u＝u gabc-u abc。
The specific formula for calculation of voltage error is:
e u · = u g a b c - e a b c + Ri a b c + L di a b c d t + ρ u .
In formula, L is the synchronous inductance of virtual synchronous generator, and R is the synchronous resistance of virtual synchronous generator, e abc, u abcand i abcbe respectively the machine end electromotive force of virtual synchronous generator, voltage and electric current, e ufor line voltage u gabcwith the set end voltage u of virtual synchronous generator abcdifference, for voltage error, ρ ufor uncertain factor.
Have an impact owing to there is the stability of possible factor to system in system, thus the set end voltage of virtual synchronous generator and the synchronous of line voltage can be affected, thus in the synchronizing process of the set end voltage and line voltage that control virtual synchronous generator, not only need to consider the difference between the set end voltage of virtual synchronous generator and line voltage, and need to consider other influences factor, increase uncertain factor ρ u, to represent the influencing factor that may exist in a practical situation, by prior great many of experiments, this ρ can be obtained u, i.e. ρ ufor the known constant obtained based on experience value.Due to some the possible disturbances existed in system, both consider the difference between the set end voltage of virtual synchronous generator and line voltage, consider uncertain factor ρ again u, adopt sliding formwork to control when controlling system, to realize comparatively accurate control effects.
Wherein in an embodiment, the concrete formula of sliding-mode surface design is:
S u = e u · + ke u .
In formula, S ufor sliding-mode surface, k is difference proportionality coefficient.
Wherein in an embodiment, the mechanical equation of virtual synchronous generator is expressed as:
J d ω d t = T m - T e - T d = T m - T e - D ( ω - ω 0 ) ;
T ebe expressed as:
T e＝P e/ω＝(e ai a+e bi b+e ci c)/ω；
In formula, J is the inertia time constant of virtual synchronous generator, and ω is the angular speed of virtual synchronous generator, ω 0for synchronized angular speed, T m, T eand T dbe respectively the mechanical rotating shaft of virtual synchronous generator, electromagnetic torque and damping torque, D is damping coefficient, P efor the electromagnetic power that virtual synchronous generator exports, e a, e band e cbe respectively the machine end electromotive force of the A phase of virtual synchronous generator, B phase and C phase, i a, i band i cbe respectively the machine end electric current of the A phase of virtual synchronous generator, B phase and C phase.By setting up the mechanical equation of described virtual synchronous generator, realize frequency modulation, pressure regulation and adjusting power to make virtual synchronous generator.Namely by the Mathematical Modeling of simulation synchronous generator, virtual synchronous generator is modeled to traditional synchronous generator, can realize adjustment and the isoparametric adjustment of voltage of power, realize synchronous with electrical network.
Adopt the mechanical equation of conventional synchronization generator to control combining inverter, combining inverter all can be compared favourably with synchronous generator in mechanism He in external characteristic.Due to the existence of J, ground combining inverter is made to have had inertia in frequency disturbance process, and due to the existence of D, make the inverter type device that generates electricity by way of merging two or more grid systems also be present in the ability of resistance system power concussion, the runnability of this Two Variables to electrical network has important improvement result.
Refer to Fig. 3, a kind of be applied to virtual synchronous generator from/grid-connected handover control system, comprising:
First sets up mould 100, for setting up mechanical equation and the electromagnetic equation of virtual synchronous generator.
Utilize the mechanical equation of virtual synchronous generator and electromagnetic equation to control virtual synchronous generator,, based on virtual synchronous generator connecting in parallel with system inverter, there is the external characteristic the same with conventional synchronization generator, set up mechanical equation and electromagnetic equation, namely set up the Mathematical Modeling of virtual synchronous generator.Utilize virtual synchronous generator techniques, conventional synchronization generator electromagnetic equation is adopted to control combining inverter, namely conventional synchronization generator electromagnetic equation is adopted to control virtual synchronous generator, make virtual synchronous generator have identical external characteristic with conventional synchronization generator, the runnability of distribution electricity generation system containing virtual synchronous generator and micro-capacitance sensor can be improved.
Compared to traditional synchronous generator, electrical network has from net and grid-connected two kinds of operational modes, need these two kinds of patterns are formulated virtual synchronous generator corresponding from/grid-connected and/from the switchover policy between net pattern.Time such as from/grid-connected switching, key is the frequency of detection of grid voltage, line voltage and the deviation of phase place, switches may produce large grid-connected impulse current when both are asynchronous.
By setting up the mechanical equation of described virtual synchronous generator, realize frequency modulation, pressure regulation and adjusting power to make virtual synchronous generator.By setting up mechanical equation and the electromagnetic equation of virtual synchronous generator, namely the Mathematical Modeling of virtual synchronous generator is established, the Mathematical Modeling of simulation synchronous generator, virtual synchronous generator is modeled to traditional synchronous generator, meritorious adjustment can be carried out to virtual synchronous generator, Reactive-power control, Current Control and from functions such as/grid-connected Synchronization Control, just can know the set end voltage how controlling virtual synchronous generator, default within the scope of/grid-connected switching error to make the difference between the set end voltage of virtual synchronous generator and line voltage be decreased in the short period, realize synchronous with the set end voltage realizing virtual synchronous generator with electrical network, carry out from/grid-connected switching again, large impulse current can not be produced like this.
First acquisition module 200, for obtaining line voltage and virtual synchronous generator terminal voltage.
The set end voltage of virtual synchronous machine is variable quantity, and line voltage can as with reference to amount, and enough hour of the error before both, can carry out from/grid-connected switching.
Second acquisition module 300, for the set end voltage according to line voltage and virtual synchronous generator, obtains the difference of the set end voltage of line voltage and virtual synchronous generator.
Also there is deviation between the set end voltage that the difference of the set end voltage of line voltage and virtual synchronous generator represents line voltage and virtual synchronous generator, do not realize synchronous.
Computing module 400, for the difference of the set end voltage according to line voltage and virtual synchronous generator, electromagnetic equation and uncertain factor, calculating voltage error.
In actual application, not only to consider the value of voltage itself, extraneous uncertain factor also may can have an impact to result, thus add uncertain factor item, guarantee that result is more accurate.
Design module 500, for difference and the voltage error of the set end voltage according to line voltage and virtual synchronous generator, design sliding-mode surface.
Virtual synchronous set end voltage is designed, the main target of voltage controller design realizes making voltage error converge to zero at finite time, in order to improve system control performance, adopt fast terminal sliding mode control strategy, and design sliding-mode surface, the switching function that sliding formwork controls, namely sliding-mode surface, what it characterized is the system performance expected, from stability angle, generally getting coefficient is just, namely difference proportionality coefficient generally get on the occasion of, different sliding-mode surfaces has different convergence characteristics, such as, linear sliding mode mask has asymptotic convergence, terminal sliding mode mask has finite time convergence control characteristic, so select different sliding-mode surfaces, dynamic response characteristic is different.Even same sliding-mode surface, difference proportionality coefficient is selected different, and the time of convergence, characteristic are also different.
Control module 600, for according to voltage error and sliding-mode surface, utilizes fast terminal sliding mode control algorithm, and the difference controlled between the set end voltage of virtual synchronous machine and line voltage reduces, and the corresponding voltage error after calculated difference reduction.
In actual applications, fast terminal sliding mode controller is selected to control, set end voltage and the line voltage of virtual synchronous machine input sliding mode controller respectively, determine both switching functions, by fast terminal sliding mode control algorithm, the difference controlled between the set end voltage of virtual synchronous machine and line voltage reduces, and ensures that error amount between the two can quick smoothly level off to zero.
Sliding formwork controls also to be variable-structure control, is the special nonlinear Control of a class in essence, and non-linear behavior is the discontinuity of control.This control strategy and other differences controlled are that " structure " of system does not fix, but can in dynamic process, and the state current according to system on purpose constantly changes, and force system according to the state trajectory motion of predetermined " sliding mode ".Can carry out designing due to sliding mode and have nothing to do with image parameter and disturbance, this just makes sliding formwork control to have quick response, corresponding Parameters variation and disturbance is insensitive, without the need to advantages such as system on-line identification, physics realization are simple.
Handover module 700, for be in when voltage error default from/grid-connected switching error scope time, virtual synchronous generator is carried out from/grid-connected switching.
Voltage error is at Finite-time convergence, and go to zero, illustrate virtual synchronous machine set end voltage can Rapid Variable Design to synchronous with line voltage, when both errors be in default from/grid-connected switching error scope time, can carry out from/grid-connected switching virtual synchronous generator.In the present embodiment, preset from/grid-connected switching error scope be within 10%.
Above-mentioned be applied to virtual synchronous generator from grid-connection control system, by obtaining the difference of the set end voltage of line voltage and virtual synchronous generator, according to the difference of the set end voltage of line voltage and virtual synchronous generator, electromagnetic equation and uncertain factor item, calculating voltage error, according to difference and the voltage error of the set end voltage of line voltage and virtual synchronous generator, design sliding-mode surface, again according to voltage error and sliding-mode surface, utilize fast terminal sliding mode control algorithm, the difference controlled between the set end voltage of virtual synchronous machine and line voltage reduces, when voltage error be in default from/grid-connected switching error scope time, virtual synchronous generator is carried out from/grid-connected switching.By above-mentioned be applied to virtual synchronous generator from grid-connected control method and system, during owing to carrying out the machine end of virtual synchronous machine from/grid-connected switching, basic synchronization between the set end voltage of virtual synchronous machine and line voltage, larger impulse current can not be produced, virtual synchronous function seamless switching can be realized.
Wherein in an embodiment, the electromagnetic equation of virtual synchronous generator is expressed as:
L di a b c d t = e a b c - u a b c - Ri a b c ;
The difference of the set end voltage of line voltage and virtual synchronous generator is expressed as:
e u＝u gabc-u abc；
The specific formula for calculation of voltage error is:
e u · = u g a b c - e a b c + Ri a b c + L di a b c d t + ρ u .
In formula, L is the synchronous inductance of virtual synchronous generator, and R is the synchronous resistance of virtual synchronous generator, e abc, u abcand i abcbe respectively the machine end electromotive force of virtual synchronous generator, voltage and electric current, e ufor line voltage u gabcwith the set end voltage u of virtual synchronous generator abcdifference, for voltage error, ρ ufor uncertain factor.
Have an impact owing to there is the stability of possible factor to system in system, thus the set end voltage of virtual synchronous generator and the synchronous of line voltage can be affected, thus in the synchronizing process of the set end voltage and line voltage that control virtual synchronous generator, not only need to consider the difference between the set end voltage of virtual synchronous generator and line voltage, and need to consider other influences factor, increase uncertain factor ρ u, to represent the influencing factor that may exist in a practical situation, by prior great many of experiments, this ρ can be obtained u, i.e. ρ ufor the known constant obtained based on experience value.Due to some the possible disturbances existed in system, both consider the difference between the set end voltage of virtual synchronous generator and line voltage, consider uncertain factor ρ again u, adopt sliding formwork to control when controlling system, to realize comparatively accurate control effects.
Wherein in an embodiment, the concrete formula of sliding-mode surface design is:
S u = e u · + ke u .
In formula, S ufor sliding-mode surface, k is difference proportionality coefficient.
Wherein in an embodiment, the mechanical equation of virtual synchronous generator is expressed as:
J d ω d t = T m - T e - T d = T m - T e - D ( ω - ω 0 ) ;
T ebe expressed as:
T e＝P e/ω＝(e ai a+e bi b+e ci c)/ω；
In formula, described J is the inertia time constant of described virtual synchronous generator, and described ω is the angular speed of described virtual synchronous generator, described ω 0for synchronized angular speed, described T m, described T eand described T dbe respectively the mechanical rotating shaft of described virtual synchronous generator, electromagnetic torque and damping torque, described D is damping coefficient, P efor the electromagnetic power that virtual synchronous generator exports, e a, e band e cbe respectively the machine end electromotive force of the A phase of virtual synchronous generator, B phase and C phase, i a, i band i cbe respectively the machine end electric current of the A phase of virtual synchronous generator, B phase and C phase.
By setting up the mechanical equation of described virtual synchronous generator, realize frequency modulation, pressure regulation and adjusting power to make virtual synchronous generator.Namely by the Mathematical Modeling of simulation synchronous generator, virtual synchronous generator is modeled to traditional synchronous generator, can realize adjustment and the isoparametric adjustment of voltage of power, realize synchronous with electrical network.
Adopt conventional synchronization generator mechanical equation to control combining inverter, combining inverter all can be compared favourably with synchronous generator in mechanism He in external characteristic.Due to the existence of J, ground combining inverter is made to have had inertia in frequency disturbance process, and due to the existence of D, make the inverter type device that generates electricity by way of merging two or more grid systems also be present in the ability of resistance system power concussion, the runnability of this Two Variables to electrical network has important improvement result.
Each technical characteristic of above embodiment can combine arbitrarily, for making description succinct, all possible combination of each technical characteristic in above-described embodiment is not all described, but, as long as the combination of these technical characteristics does not exist contradiction, be all considered to be the scope that this specification is recorded.
Above embodiment only have expressed several execution mode of the present invention, and it describes comparatively concrete and detailed, but can not therefore be construed as limiting the scope of the patent.It should be pointed out that for the person of ordinary skill of the art, without departing from the inventive concept of the premise, can also make some distortion and improvement, these all belong to protection scope of the present invention.Therefore, the protection range of patent of the present invention should be as the criterion with claims.

Claims (10)

1. be applied to virtual synchronous generator from/grid-connected a method for handover control, it is characterized in that, comprise the following steps:
Set up mechanical equation and the electromagnetic equation of virtual synchronous generator;
Obtain the set end voltage of line voltage and described virtual synchronous generator;
According to the set end voltage of described line voltage and described virtual synchronous generator, obtain the difference of the set end voltage of described line voltage and described virtual synchronous generator;
According to the described difference of the set end voltage of described line voltage and described virtual synchronous generator, described electromagnetic equation and uncertain factor, calculating voltage error;
According to described difference and the described voltage error of the set end voltage of described line voltage and described virtual synchronous generator, design sliding-mode surface;
According to described voltage error and described sliding-mode surface, utilize fast terminal sliding mode control algorithm, the described difference controlled between the set end voltage of described virtual synchronous machine and described line voltage reduces, and calculates the corresponding voltage error after the reduction of described difference;
When described voltage error be in default from/grid-connected switching error scope time, described virtual synchronous generator is carried out from/grid-connected switching.
2. according to claim 1 be applied to virtual synchronous generator from/grid-connected control method, it is characterized in that, the electromagnetic equation of described virtual synchronous generator is expressed as:
L di a b c d t = e a b c - u a b c - Ri a b c ;
The difference of the set end voltage of described line voltage and described virtual synchronous generator is expressed as:
e u＝u gabc-u abc；
The specific formula for calculation of described voltage error is:
e u · = u g a b c - e a b c + Ri a b c + L di a b c d t + ρ u ;
In formula, described L is the synchronous inductance of described virtual synchronous generator, and described R is the synchronous resistance of described virtual synchronous generator, described e abc, described u abcand described i abcbe respectively the machine end electromotive force of described virtual synchronous generator, voltage and electric current, described e ufor described line voltage u gabcwith the set end voltage u of described virtual synchronous generator abcdifference, described in for described voltage error, described ρ ufor described uncertain factor.
3. according to claim 2 be applied to virtual synchronous generator from/grid-connected control method, it is characterized in that, the concrete formula of described sliding-mode surface design is:
S u = e u · + ke u ;
In formula, described S ufor described sliding-mode surface, described k is difference proportionality coefficient.
4. according to claim 1 any one be applied to virtual synchronous generator from/grid-connected control method, it is characterized in that, the mechanical equation of described virtual synchronous generator is expressed as:
J d ω d t = T m - T e - T d = T m - T e - D ( ω - ω 0 ) ;
Described T ebe expressed as:
T e＝P e/ω＝(e ai a+e bi b+e ci c)/ω；
In formula, described J is the inertia time constant of described virtual synchronous generator, and described ω is the angular speed of described virtual synchronous generator, described ω 0for synchronized angular speed, described T m, described T eand described T dbe respectively the mechanical rotating shaft of described virtual synchronous generator, electromagnetic torque and damping torque, described D is damping coefficient, described P efor the electromagnetic power that described virtual synchronous generator exports, described e a, described e band described e cbe respectively the machine end electromotive force of the A phase of described virtual synchronous generator, B phase and C phase, described i a, described i band described i cbe respectively the machine end electric current of the A phase of described virtual synchronous generator, B phase and C phase;
By setting up the mechanical equation of described virtual synchronous generator, realize frequency modulation, pressure regulation and adjusting power to make described virtual synchronous generator.
5. according to claim 1 be applied to virtual synchronous generator from/grid-connected control method, it is characterized in that, described default from/grid-connected switching error scope be within 10%.
6. be applied to virtual synchronous generator from/grid-connected a handover control system, it is characterized in that, comprising:
First sets up module, for setting up mechanical equation and the electromagnetic equation of virtual synchronous generator;
First acquisition module, for obtaining the set end voltage of line voltage and described virtual synchronous generator;
Second acquisition module, for the set end voltage according to described line voltage and described virtual synchronous generator, obtains the difference of the set end voltage of described line voltage and described virtual synchronous generator;
Computing module, for the described difference of the set end voltage according to described line voltage and described virtual synchronous generator, described electromagnetic equation and uncertain factor, calculating voltage error;
Design module, for described difference and the described voltage error of the set end voltage according to described line voltage and described virtual synchronous generator, design sliding-mode surface;
Control module, for according to described voltage error and described sliding-mode surface, utilize fast terminal sliding mode control algorithm, the described difference controlled between the set end voltage of described virtual synchronous machine and described line voltage reduces, and calculates the corresponding voltage error after the reduction of described difference;
Handover module, for be in when described voltage error default from/grid-connected switching error scope time, described virtual synchronous generator is carried out from/grid-connected switching.
7. according to claim 6 be applied to virtual synchronous generator from/grid-connection control system, it is characterized in that, the electromagnetic equation of described virtual synchronous generator is expressed as:
L di a b c d t = e a b c - u a b c - Ri a b c ;
The difference of the set end voltage of described line voltage and described virtual synchronous generator is expressed as:
e u＝u gabc-u abc；
The specific formula for calculation of described voltage error is:
e u · = u g a b c - e a b c + Ri a b c + L di a b c d t + ρ u ;
In formula, described L is the synchronous inductance of described virtual synchronous generator, and described R is the synchronous resistance of described virtual synchronous generator, described e abc, described u abcand described i abcbe respectively the machine end electromotive force of described virtual synchronous generator, voltage and electric current, described e ufor described line voltage u gabcwith the set end voltage u of described virtual synchronous generator abcdifference, described in for described voltage error, described ρ ufor described uncertain factor.
8. according to claim 7 be applied to virtual synchronous generator from/grid-connection control system, it is characterized in that,
The concrete formula of described sliding-mode surface design is:
S u = e u · + ke u ;
In formula, described S ufor described sliding-mode surface, described k is difference proportionality coefficient.
9. according to claim 1 be applied to virtual synchronous generator from/grid-connection control system, it is characterized in that, the mechanical equation of described virtual synchronous generator is expressed as:
J d ω d t = T m - T e - T d = T m - T e - D ( ω - ω 0 ) ;
Described T ebe expressed as:
T e＝P e/ω＝(e ai a+e bi b+e ci c)/ω；
In formula, described J is the inertia time constant of described virtual synchronous generator, and described ω is the angular speed of described virtual synchronous generator, described ω 0for synchronized angular speed, described T m, described T eand described T dbe respectively the mechanical rotating shaft of described virtual synchronous generator, electromagnetic torque and damping torque, described D is damping coefficient, described P efor the electromagnetic power that described virtual synchronous generator exports, described e a, described e band described e cbe respectively the machine end electromotive force of the A phase of described virtual synchronous generator, B phase and C phase, described i a, described i band described i cbe respectively the machine end electric current of the A phase of described virtual synchronous generator, B phase and C phase;
By setting up the mechanical equation of described virtual synchronous generator, realize frequency modulation, pressure regulation and adjusting power to make described virtual synchronous generator.
10. according to claim 1 be applied to virtual synchronous generator from/grid-connection control system, it is characterized in that, described default from/grid-connected switching error scope be within 10%.
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