CN108376998B - The symmetric fault transient state control method of meter and virtual synchronous machine saturated characteristic - Google Patents
The symmetric fault transient state control method of meter and virtual synchronous machine saturated characteristic Download PDFInfo
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- CN108376998B CN108376998B CN201810282128.XA CN201810282128A CN108376998B CN 108376998 B CN108376998 B CN 108376998B CN 201810282128 A CN201810282128 A CN 201810282128A CN 108376998 B CN108376998 B CN 108376998B
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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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- 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
- H02J3/24—Arrangements for preventing or reducing oscillations of power in networks
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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
- H02J3/46—Controlling of the sharing of output between the generators, converters, or transformers
- H02J3/48—Controlling the sharing of the in-phase component
-
- 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
- H02J3/46—Controlling of the sharing of output between the generators, converters, or transformers
- H02J3/50—Controlling the sharing of the out-of-phase component
-
- 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
- H02J2203/00—Indexing scheme relating to details of circuit arrangements for AC mains or AC distribution networks
- H02J2203/20—Simulating, e g planning, reliability check, modelling or computer assisted design [CAD]
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Abstract
The invention discloses meter and the symmetric fault Transient Stability Analysis and control method of virtual synchronous machine saturated characteristic.The research method about the big transient stability for interfering lower virtual synchronous machine when symmetrical short-circuit failure occurs for power grid and is not suitable at present, the present invention by before establishing power grid symmetric fault, the system equivalent model in failure and after failure, pass through the transient stability mechanism and Instability under conditions of analysis meter and virtual synchronous machine saturated characteristic, the major influence factors for obtaining power system transient stability are the size of generator rotor angle, and corresponding measure is proposed on this basis, transient state energy effectively is inhibited, improves the transient stability of system.
Description
Technical field
The present invention relates to distributed power generation and power electronics field more particularly to a kind of meter and virtual synchronous machine saturations
The symmetric fault transient state control method of characteristic.
Background technique
Most of electric power of traditional power grid are provided by large synchronous generator, since synchronous generator rotor has machine
Tool rotary inertia can contain a large amount of kinetic energy, when disturbance or failure occur for power grid, can be carried out using the kinetic energy and power grid of rotor
Energy exchange, to maintain the stability of power grid.It is main with inverter but in recent years, with the development of new energy power generation technology
The distributed generation resource of interface is more and more widely used, compared with the synchronous generator in conventional electric power system, inversion
Device hardly has rotary inertia, it is difficult to provide necessary inertia and Damper Braces for system, the safe and stable operation of power grid is asked
Topic is more severe.Virtual synchronous machine passes through the characteristics such as ontology model, active frequency modulation and the idle pressure regulation of simulation synchronous generator,
Make inverter that can all compare favourably with conventional synchronization generator from operating mechanism and external characteristics.Therefore, virtual synchronous machine controls
Inverter has load angle characteristic similar with synchronous generator, equally exists angle stability problem.
Small interference stability Journal of Sex Research is focused primarily upon for virtual synchronous machine stability study at present, to it under big interference
Transient stability Study on Problems it is relatively fewer.
Entitled the virtual angle stability Analysis on Mechanism of inverter " sagging control ", " Automation of Electric Systems ", 2016 years the
12 phases page 117~123 and entitled " control method for improving the sagging control virtual generator rotor angle transient stability of inverter ", " power train
System automation ", the 12nd phase article of page 56~62 in 2017 obtains inverter by defining the virtual generator rotor angle of inverter respectively
Virtual load angle characteristic when electric current unsaturation and the virtual load angle characteristic under current saturation, analyze inverter on this basis
Virtual generator rotor angle synchronism stability mechanism and Instability, and corresponding control strategy is proposed, but analyze in this two articles big dry
It disturbs and falls from external voltage amplitude, and think virtual synchronous machine output voltage VoIt can also remain unchanged always under big interference,
And it the analysis method and is not suitable for when short trouble occurs for route；In addition, distributed generation resource often connects in a practical situation
It being connected in low pressure or middle-voltage network, the resistive component in route be can not ignore, and the influence of line resistance is not considered in text,
Only analyze the power-angle stability under pure perceptual transmission line of electricity.
Entitled " Synchronous Instability Mechanism of P-f Droop-Controlled
Voltage Source Converter Caused by Current Saturation ", IEEE TRANSACTIONS ON
(the synchronization under the sagging control inverter current saturation of voltage-type of POWER SYSTEMS, VOL.31, NO.6, NOVEMBER 2016
Failure Mechanism, IEEE electric system transactions, the 6th phase page 5206~5207 of volume 31 in 2016) article, it is indicated that parallel network reverse
The problem of device is easy to happen Transient Instability under conditions of current limit, but for the Transient Instability reason and unstability of inverter
Process lack analyse in depth, and its use and in pessimistic concurrency control also not consider line resistance influence, the inverter obtained
Power-angle curve when saturation in symmetric fault and is not suitable for.
Entitled " virtual synchronous generator modeling and improvement control under power grid symmetric fault ", " Proceedings of the CSEE ",
The 2nd phase article of page 403~411 of volume 37 in 2017, the essential characteristic and shadow of fault current when by analysis symmetric fault
The factor of sound proposes a kind of fault current limitation method, but it is continued to use when carrying out Transient Stability Analysis to virtual synchronous machine
The power characteristic of conventional synchronization generator, virtual synchronous machine do not have the strong overload energy of synchronous generator as power electronic equipment
Power cannot provide short circuit current, and the Transient Stability Analysis method in conventional electric power system is not suitable for virtual synchronous machine.
In summary document, there are following for the existing virtual synchronous machine Transient angle stability research under big interference
It is insufficient:
1) influence that line resistance is had ignored in analysis only analyzes the power-angle stability under pure perceptual transmission line of electricity, compared with
For idealization；
2) big interference is fallen mainly from external voltage amplitude, and this kind is analyzed when symmetrical short-circuit failure occurs on route
Method is simultaneously not suitable for；
3) have ignored virtual synchronous machine it is idle-the sagging adjusting of voltage caused by voltage reduce, that is, think that virtual synchronous machine is defeated
Voltage V outoIt remains unchanged, but actually due to the presence of amplitude limit link, Voltage Drop is larger in failure process, can not ignore,
And after cutting off failure, virtual synchronous machine output voltage VoRise process also will affect the transient state energy and its stabilization of system
Property.
Summary of the invention
The invention discloses meter and the symmetric fault Transient Stability Analysis and control method of virtual synchronous machine saturated characteristic.
At present about the research method of the big transient stability for interfering lower virtual synchronous machine when symmetrical short-circuit failure occurs for power grid not
Be applicable in, the present invention by before establishing power grid symmetric fault, the system equivalent model in failure and after failure, in meter and virtual synchronous
Transient stability mechanism and Instability are analyzed under conditions of machine saturated characteristic, show that the influence factor of power system transient stability is function
The size at angle, and corresponding measure is proposed on this basis, transient state energy is effectively inhibited, the transient stability of system is improved
Property.
To solve problems of the prior art, the present invention provides a kind of meter and pairs of virtual synchronous machine saturated characteristic
Claim fault transient control method, comprising the following steps:
Step 1, setting route symmetrical short-circuit fault point f and fault section [t1,t2]；
Step 2 calculates its rated current virtual value I according to virtual synchronous machine rated capacity SN:
Wherein, UNFor virtual synchronous machine voltage rating virtual value；
Step 3, according to the virtual synchronous machine rated current virtual value I acquired in step 2NSet virtual synchronous machine output electricity
Stream instruction amplitude limit value IM, IM=(1.1~1.3) IN；
Step 4 exports current-order amplitude limit value I according to the virtual synchronous machine in step 3MIt determines empty in symmetrical short-circuit failure
Quasi- synchronous machine active power of output Pf:
Pf=3 | IM|2·R1
Wherein, R1For virtual synchronous machine to the equivalent resistance of fault point f；
Step 5, the virtual synchronous generator three-phase of sampling export electric current ia,ib,ic, virtual synchronous generator three-phase output electricity
Press ua,ub,uc, virtual synchronous generator filter inductance three-phase current iLa,iLb,iLc, and calculate the output of virtual synchronous generator
Active-power PeAnd reactive power Qe, the active-power P of the virtual synchronous generator outputeAnd reactive power QeCalculating formula
It is respectively as follows:
Pe=uaia+ubib+ucic
Step 6 sets the initial active power reference value of virtual synchronous machine as Pref, the reference value of virtual synchronous machine reactive power
Qref=0, virtual synchronous generates electricity before obtaining failure according to the sagging adjusting of the equation of rotor motion of virtual synchronous machine and idle-voltage
Machine built-in potential amplitude instructs E and built-in potential phase δ, the meter of the virtual synchronous generator built-in potential amplitude E and built-in potential phase δ
Formula is respectively as follows:
E=Eref-n(Qref-Qe)；
Wherein, ErefFor the reference value of output line voltage, n is the sagging coefficient of reactive power, and J is virtual synchronous generator
Rotary inertia；ω is the angular speed of virtual synchronous generator output, ω0For rated angular velocity；M is the sagging system of active power
Number；
Compare the initial active power reference value P of virtual synchronous machinerefIt is active with virtual synchronous machine output in symmetrical short-circuit failure
Power PfNumerical value, if Pref≠Pf, in failure start time t1, by the initial active power reference value P of virtual synchronous machinerefNumber
It is P that value, which is updated to active power reference value in virtual synchronous machine failure,ref' numerical value, wherein wattful power in virtual synchronous machine failure
Rate reference value Pref' numberical range it is defined below:
If Pref< Pf, Pref’∝(Pf, S)；
If Pref> Pf, Pref' ∝ (0, Pf)；
Step 7, the virtual synchronous generator three-phase output voltage u that will be sampled in step 5a,ub,ucIt is quiet to carry out three-phase
Only coordinate system obtains virtual synchronous generator output voltage d axis component u to the conversion of two-phase rotating coordinate systemdWith output voltage q
Axis component uq, the virtual synchronous generator filter inductance three-phase current i that will be sampled in step 5La,iLb,iLcIt is quiet to carry out three-phase
Only coordinate system obtains virtual synchronous generator filter inductance electric current d axis component i to the conversion of two-phase rotating coordinate systemLdAnd filtering
Inductive current q axis component iLq；
Virtual synchronous generator output voltage d axis component udWith output voltage q axis component uqExpression formula are as follows:
Virtual synchronous generator filter inductance electric current d axis component iLdWith filter inductance electric current q axis component iLqExpression formula are as follows:
Wherein, t is virtual synchronous machine runing time；
Virtual synchronous machine built-in potential amplitude obtained in step 6 is instructed virtual synchronous obtained in E and step 7 by step 8
Generator output voltage d axis component udBy d shaft voltage closed-loop control equation, the filtering of virtual synchronous generator output voltage is obtained
Inductive current d axis instruction value iLdref；Enable the q axis instruction value u of virtual synchronous machine output voltageqref=0, it will be obtained in itself and step 7
The virtual synchronous generator output voltage q axis component u arrivedqBy q shaft voltage closed-loop control equation, virtual synchronous generator is obtained
Output voltage filter inductance electric current q axis instruction value iLqref, the virtual synchronous generator output voltage filter inductance electric current d axis refers to
Enable value iLdrefWith virtual synchronous generator output voltage filter inductance electric current q axis instruction value iLqrefExpression formula is respectively as follows:
Wherein, kvpFor voltage close loop proportional controller coefficient, kviFor voltage close loop integral controller coefficient, s La Pula
This operator；
Step 9, setting virtual synchronous generator filter inductance electric current d axis limits value iLdmaxIt is filtered with virtual synchronous generator
Inductive current q axis limits value iLqmax, which makes virtual synchronous generator filter inductance electric current d obtained in step 8
Axis instruction value iLdrefWith virtual synchronous generator filter inductance electric current q axis instruction value iLqrefMeet following constraint:
Virtual synchronous generator filter inductance electric current d axis instruction value iLdrefWith virtual synchronous generator filter inductance electric current q
Axis instruction value iLqrefAfter limiter, virtual synchronous generator voltage closed loop d axis output valve i is obtainedLdref' and virtual synchronous
Generator voltage closed loop q axis output valve iLqref'；
Step 10, the virtual synchronous generator voltage closed loop d axis output valve i for obtaining step 9Ldref' and step 7 in obtain
Virtual synchronous generator filter inductance electric current d axis component iLdBy d shaft current closed-loop control equation, d axis output signal is obtained
Ud；The virtual synchronous generator voltage closed loop q axis output valve i that step 9 is obtainedLqref' sent out with virtual synchronous obtained in step 7
Motor filter inductance electric current q axis component iLqBy q shaft current closed-loop control equation, q axis output signal U is obtainedq；The d axis is defeated
Signal U outdWith q axis output signal UqAre as follows:
Wherein, kipFor current closed-loop proportional controller coefficient, kiiFor current closed-loop integral controller coefficient；
Step 11, by d axis output signal U obtained in step 10dWith q axis output signal UqIn the built-in potential that step 6 obtains
The conversion of two-phase rotating coordinate system to three-phase static coordinate system is done under phase δ, obtains the three-phase tune of virtual synchronous machine bridge arm voltage
Wave U processedma,Umb,Umc, and the driving signal after PWM modulation as IGBT circuit；The three of the virtual synchronous machine bridge arm voltage
Phase modulating wave Uma,Umb,UmcExpression formula are as follows:
Uma=Udcosδ+Uqsinδ
The symmetric fault Transient Stability Analysis and control method of meter disclosed by the invention and virtual synchronous machine saturated characteristic,
Compared with the conventional method, its advantages are embodied in:
1, distributed generation resource in actual conditions is considered often to be connected in low pressure or middle-voltage network, line resistance without
The case where method is ignored, power-angle curve is applicable in resistance inductive circuit, and existing analysis method has ignored route and filter
The resistance of wave inductance, idealization.
2, existing analysis method thinks that virtual synchronous machine output voltage remains unchanged in whole process, and the present invention considers
Virtual synchronous machine output voltage falls larger situation in failure process caused by amplitude limit link, and count and excision failure it
Afterwards, virtual synchronous machine output voltage VoRise process for system transient state energy and its stability influence.
3, for having continued to use synchronous generator in conventional electric power system in virtual synchronous machine transient rotor angle stability in existing literature
The power characteristic of machine, and transient stability is judged using traditional equal area criterion, but virtual synchronous machine is as electric power
For electronic device from synchronous generator there are different operation characteristics, the present invention cannot provide virtual synchronous machine to the spy of short circuit current
Property is taken into account, and has obtained the symmetric fault transient stability control method suitable for virtual synchronous machine.
4, it by being modeled to before grid-connected system symmetric fault, in failure, after failure, obtains empty under different operating statuses
The transient behavior of quasi- synchronous machine and the influence factor of virtual synchronous machine transient stability, propose based on active power regulation
Transient state control method effectively inhibits the over-voltage occurred in transient process, overcurrent and power overshoot phenomenon.
Detailed description of the invention
Fig. 1 is virtual synchronous of embodiment of the present invention machine control block diagram.
Fig. 2 is the system equivalent circuit diagram when present invention implements f point generation symmetrical short-circuit failure on the line.
Fig. 3 is the initial active power reference value P of virtual synchronous machinerefIt is exported less than virtual synchronous machine in symmetrical short-circuit failure
Active-power PfShi Fasheng symmetrical short-circuit failure and fault section [t1,t2] be [1.5s, 2s] when current waveform.
Fig. 4 is the initial active power reference value P of virtual synchronous machinerefIt is exported less than virtual synchronous machine in symmetrical short-circuit failure
Active-power PfShi Fasheng symmetrical short-circuit failure and fault section [t1,t2] be [1.5s, 2s] when voltage waveform.
Fig. 5 is the initial active power reference value P of virtual synchronous machinerefIt is exported less than virtual synchronous machine in symmetrical short-circuit failure
Active-power PfShi Fasheng symmetrical short-circuit failure and fault section [t1,t2] be [1.5s, 2s] when output power waveform.
Fig. 6 is the initial active power reference value P of virtual synchronous machinerefIt is exported less than virtual synchronous machine in symmetrical short-circuit failure
Active-power Pf, fault section [t1,t2] it is [1.5s, 2s] and in failure start time t1By the initial wattful power of virtual synchronous machine
Rate reference value PrefIt is updated to Pref' when current waveform.
Fig. 7 is the initial active power reference value P of virtual synchronous machinerefIt is exported less than virtual synchronous machine in symmetrical short-circuit failure
Active-power Pf, fault section [t1,t2] it is [1.5s, 2s] and in failure start time t1By the initial wattful power of virtual synchronous machine
Rate reference value PrefIt is updated to Pref' when voltage waveform.
Fig. 8 is the initial active power reference value P of virtual synchronous machinerefIt is exported less than virtual synchronous machine in symmetrical short-circuit failure
Active-power Pf, fault section [t1,t2] it is [1.5s, 2s] and in failure start time t1By the initial wattful power of virtual synchronous machine
Rate reference value PrefIt is updated to Pref' when output power waveform.
Fig. 9 is the initial active power reference value P of virtual synchronous machinerefIt is exported greater than virtual synchronous machine in symmetrical short-circuit failure
Active-power PfAnd fault section [t1,t2] be [1.5s, 2s] when current waveform.
Figure 10 is the initial active power reference value P of virtual synchronous machinerefIt is exported greater than virtual synchronous machine in symmetrical short-circuit failure
Active-power PfAnd fault section [t1,t2] be [1.5s, 2s] when voltage waveform.
Figure 11 is the initial active power reference value P of virtual synchronous machinerefIt is exported greater than virtual synchronous machine in symmetrical short-circuit failure
Active-power PfAnd fault section [t1,t2] be [1.5s, 2s] when output power waveform.
Figure 12 is the initial active power reference value P of virtual synchronous machinerefIt is exported greater than virtual synchronous machine in symmetrical short-circuit failure
Active-power PfAnd fault section [t1,t2] be [1.5s, 2s] when generator rotor angle waveform.
Figure 13 is the initial active power reference value P of virtual synchronous machinerefIt is exported greater than virtual synchronous machine in symmetrical short-circuit failure
Active-power PfAnd fault section [t1,t2] be [1.5s, 2s] when frequency waveform.
Figure 14 is the initial active power reference value P of virtual synchronous machinerefIt is exported greater than virtual synchronous machine in symmetrical short-circuit failure
Active-power Pf, fault section [t1,t2] it is [1.5s, 2s] and in failure start time t1By the initial wattful power of virtual synchronous machine
Rate reference value PrefIt is updated to Pref' when current waveform.
Figure 15 is the initial active power reference value P of virtual synchronous machinerefIt is exported greater than virtual synchronous machine in symmetrical short-circuit failure
Active-power Pf, fault section [t1,t2] it is [1.5s, 2s] and in failure start time t1By the initial wattful power of virtual synchronous machine
Rate reference value PrefIt is updated to Pref' when voltage waveform.
Figure 16 is the initial active power reference value P of virtual synchronous machinerefIt is exported greater than virtual synchronous machine in symmetrical short-circuit failure
Active-power Pf, fault section [t1,t2] it is [1.5s, 2s] and in failure start time t1By the initial wattful power of virtual synchronous machine
Rate reference value PrefIt is updated to Pref' when output power waveform.
Figure 17 is the initial active power reference value P of virtual synchronous machinerefIt is exported greater than virtual synchronous machine in symmetrical short-circuit failure
Active-power Pf, fault section [t1,t2] it is [1.5s, 2s] and in failure start time t1By the initial wattful power of virtual synchronous machine
Rate reference value PrefIt is updated to Pref' when generator rotor angle waveform.
Figure 18 is the initial active power reference value P of virtual synchronous machinerefIt is exported greater than virtual synchronous machine in symmetrical short-circuit failure
Active-power Pf, fault section [t1,t2] it is [1.5s, 2s] and in failure start time t1By the initial wattful power of virtual synchronous machine
Rate reference value PrefIt is updated to Pref' when frequency waveform.
Specific embodiment
The present invention is further described with example with reference to the accompanying drawing.
Fig. 1 is virtual synchronous of embodiment of the present invention generator control block diagram, and DC source as shown in the drawing passes through virtual synchronous
Machine inversion is AC energy, and the amplitude of virtual synchronous machine rated output line voltage is 380V, frequency 50Hz.Alternating current is through filtering
Point of common coupling is accessed by line impedance after wave inductance and filter capacitor filtering.Design parameter is as follows: bridge arm side filter inductance
Lf=0.1mH, filter capacitor Cf=300 μ F, line resistance Rg=0.1 Ω, line inductance Lg=1mH.
Fig. 2 is system equivalent circuit diagram when symmetrical short-circuit failure occurs for the embodiment of the present invention, and setting fault point f is to virtually
The equivalent resistance R of synchronous machine1=0.04 Ω.
By Fig. 1 and Fig. 2 as it can be seen that the symmetric fault transient state controlling party of meter of the present invention and virtual synchronous machine saturated characteristic
Method, comprising the following steps:
Step 1, setting route symmetrical short-circuit fault point f and fault section [t1,t2], fault section [t in the present embodiment1,
t2] it is [1.5s, 2s].
Step 2 calculates its rated current virtual value I according to virtual synchronous machine rated capacity SN:
Wherein, UNFor virtual synchronous machine voltage rating virtual value, virtual synchronous machine rated capacity S=in the present embodiment
500kW, virtual synchronous machine voltage rating virtual value UN=220V, rated current virtual value IN=757.6A.
Step 3, according to the virtual synchronous machine rated current virtual value I acquired in step 2NSet virtual synchronous machine output electricity
Stream instruction amplitude limit value IM, IM=(1.1~1.3) IN, I in the present embodimentM=874.6A.
Step 4 exports current-order amplitude limit value I according to the virtual synchronous machine in step 3MIt determines empty in symmetrical short-circuit failure
Quasi- synchronous machine active power of output Pf:
Pf=3 | IM|2·R1
Wherein, R1For virtual synchronous machine to the equivalent resistance of fault point f, fault point f is to virtual synchronous machine in the present embodiment
Equivalent resistance R1=0.04 Ω, virtual synchronous machine active power of output P in symmetrical short-circuit failuref=92kW.
Step 5, the virtual synchronous generator three-phase of sampling export electric current ia,ib,ic, virtual synchronous generator three-phase output electricity
Press ua,ub,uc, filter inductance three-phase current iLa,iLb,iLc, and calculate the active-power P of virtual synchronous generator outputeAnd nothing
Function power Qe, the active-power P of the virtual synchronous generator outputeAnd reactive power QeCalculating formula be respectively as follows:
Pe=uaia+ubib+ucic；
Step 6 sets the initial active power reference value of virtual synchronous machine as Pref, the reference value of virtual synchronous machine reactive power
Qref=0, virtual synchronous generates electricity before obtaining failure according to the sagging adjusting of the equation of rotor motion of virtual synchronous machine and idle-voltage
Machine built-in potential amplitude instructs E and built-in potential phase δ, the meter of the virtual synchronous generator built-in potential amplitude E and built-in potential phase δ
Formula is respectively as follows:
E=Eref-n(Qref-Qe)；
Wherein, ErefFor the reference value of output line voltage, n is the sagging coefficient of reactive power, and J is virtual synchronous generator
Rotary inertia；ω is the angular speed of virtual synchronous generator output, ω0For rated angular velocity；M is the sagging system of active power
Number.The reference value E of output line voltage in the present embodimentref=311V, sagging coefficient n=1.52 × 10 of reactive power-5, virtually
The rotary inertia J=50kgm of synchronous generator2, rated angular velocity ω0=314rad/s, the sagging Coefficient m of active power=
1.27×10-7。
Compare the initial active power reference value P of virtual synchronous machinerefIt is active with virtual synchronous machine output in symmetrical short-circuit failure
Power PfNumerical value, if Pref≠Pf, in failure start time t1, by the initial active power reference value P of virtual synchronous machinerefNumber
It is P that value, which is updated to active power reference value in virtual synchronous machine failure,ref' numerical value, wherein wattful power in virtual synchronous machine failure
Rate reference value Pref' numberical range it is defined below:
If Pref< Pf, Pref’∝(Pf, S)；
If Pref> Pf, Pref' ∝ (0, Pf)；
In the present embodiment, the first operating condition, that is, Pref< PfWhen, if Pref=70kW, updated value Pref'=400KW；Second
Operating condition, that is, Pref> PfWhen, if Pref=400kW, updated value Pref'=70KW.
Step 7, the virtual synchronous generator three-phase output voltage u that will be sampled in step 5a,ub,ucIt is quiet to carry out three-phase
Only coordinate system obtains virtual synchronous generator output voltage d axis component u to the conversion of two-phase rotating coordinate systemdWith output voltage q
Axis component uq, the virtual synchronous generator filter inductance three-phase current i that will be sampled in step 5La,iLb,iLcIt is quiet to carry out three-phase
Only coordinate system obtains virtual synchronous generator filter inductance electric current d axis component i to the conversion of two-phase rotating coordinate systemLdAnd filtering
Inductive current q axis component iLq；
Virtual synchronous generator output voltage d axis component udWith output voltage q axis component uqExpression formula are as follows:
Virtual synchronous generator filter inductance electric current d axis component iLdWith filter inductance electric current q axis component iLqExpression formula are as follows:
Wherein, t is virtual synchronous machine runing time.
Virtual synchronous machine built-in potential amplitude obtained in step 6 is instructed virtual synchronous obtained in E and step 7 by step 8
Generator output voltage d axis component udBy d shaft voltage closed-loop control equation, the filtering of virtual synchronous generator output voltage is obtained
Inductive current d axis instruction value iLdref；Enable the q axis instruction value u of virtual synchronous machine output voltageqref=0, it will be obtained in itself and step 7
The virtual synchronous generator output voltage q axis component u arrivedqBy q shaft voltage closed-loop control equation, virtual synchronous generator is obtained
Output voltage filter inductance electric current q axis instruction value iLqref, the virtual synchronous generator output voltage filter inductance electric current d axis refers to
Enable value iLdrefWith virtual synchronous generator output voltage filter inductance electric current q axis instruction value iLqrefExpression formula is respectively as follows:
Wherein, kvpFor voltage close loop proportional controller coefficient, kviFor voltage close loop integral controller coefficient, s La Pula
This operator.Voltage close loop proportional controller coefficient k in the present embodimentvp=1.5, voltage close loop integral controller coefficient kvi=50.
Step 9, setting virtual synchronous generator filter inductance electric current d axis limits value iLdmaxIt is filtered with virtual synchronous generator
Inductive current q axis limits value iLqmax, which makes virtual synchronous generator filter inductance electric current d obtained in step 8
Axis instruction value iLdrefWith virtual synchronous generator filter inductance electric current q axis instruction value iLqrefMeet following constraint:
Virtual synchronous generator filter inductance electric current d axis instruction value iLdrefWith virtual synchronous generator filter inductance electric current q
Axis instruction value iLqrefAfter limiter, virtual synchronous generator voltage closed loop d axis output valve i is obtainedLdref' and virtual synchronous
Generator voltage closed loop q axis output valve iLqref'.Filter inductance electric current d axis limits value i in the present embodimentLdmax=848A, filtering
Inductive current q axis limits value iLqmax=212A.
Step 10, the virtual synchronous generator voltage closed loop d axis output valve i for obtaining step 9Ldref' and step 7 in obtain
Virtual synchronous generator filter inductance electric current d axis component iLdBy d shaft current closed-loop control equation, d axis output signal is obtained
Ud；The virtual synchronous generator voltage closed loop q axis output valve i that step 9 is obtainedLqref' sent out with virtual synchronous obtained in step 7
Motor filter inductance electric current q axis component iLqBy q shaft current closed-loop control equation, q axis output signal U is obtainedq；The d axis is defeated
Signal U outdWith q axis output signal UqAre as follows:
Wherein, kipFor current closed-loop proportional controller coefficient, kiiFor current closed-loop integral controller coefficient.The present embodiment
Middle current closed-loop proportional controller coefficient kip=25, current closed-loop integral controller coefficient kii=0.
Step 11, by d axis output signal U obtained in step 10dWith q axis output signal UqIn the built-in potential that step 6 obtains
The conversion of two-phase rotating coordinate system to three-phase static coordinate system is done under phase δ, obtains the three-phase tune of virtual synchronous machine bridge arm voltage
Wave U processedma,Umb,Umc, and the driving signal after PWM modulation as IGBT circuit；The three of the virtual synchronous machine bridge arm voltage
Phase modulating wave Uma,Umb,UmcExpression formula are as follows:
Uma=Udcosδ+Uqsinδ
Fig. 3 is the initial active power reference value P of virtual synchronous machinerefIt is exported less than virtual synchronous machine in symmetrical short-circuit failure
Active-power PfShi Fasheng symmetrical short-circuit failure and fault section [t1,t2] be [1.5s, 2s] when current waveform, it can be seen that
Fall after failure removal in that case larger in a period of time, rush of current will cause to virtual synchronous generator, it is right
System stability affects greatly.
Fig. 4 is voltage waveform of the operating condition with Fig. 3 when identical, it can be seen that in that case at latter section of failure removal
Interior recovery rate is larger, causes overvoltage impact to virtual synchronous generator, not good for system stability.
Fig. 5 is output power waveform of the operating condition with Fig. 3 when identical, it can be seen that latter in failure removal in that case
Oscillation of power is larger in the section time, and transient state energy is larger in transient process, not good for system stability.
Fig. 6 is the initial active power reference value P of virtual synchronous machinerefIt is exported less than virtual synchronous machine in symmetrical short-circuit failure
Active-power PfShi Fasheng symmetrical short-circuit failure, fault section [t1,t2] it is [1.5s, 2s], but wattful power is enabled after failure starts
Rate reference value is updated to PrefCurrent waveform when '=400kW is compared with Fig. 3, rush of current after failure removal in the case of this kind
Smaller, system stability is preferable when transient state.
Fig. 7 is voltage waveform of the operating condition with Fig. 6 when identical, is compared with Fig. 4, will not be to void after failure removal in the case of this kind
Quasi- synchronous generator causes overvoltage impact, and stability is preferable.
Fig. 8 is output power waveform of the operating condition with Fig. 6 when identical, is compared with Fig. 5, transient state after failure removal in the case of this kind
Energy is smaller, and power swing is little, improves system stability.
Fig. 9 is the initial active power reference value P of virtual synchronous machinerefIt is exported greater than virtual synchronous machine in symmetrical short-circuit failure
Active-power PfShi Fasheng symmetrical short-circuit failure and fault section [t1,t2] be [1.5s, 2s] when current waveform, it can be seen that
Fall in a period of time after failure removal in that case it is larger, occur over-current phenomenon avoidance, virtual synchronous machine is damaged.
Figure 10 is voltage waveform of the operating condition with Fig. 9 when identical, it can be seen that in that case at latter section of failure removal
Recovery rate is larger in time, and over-voltage phenomenon occurs, equally damages to virtual synchronous generator.
Figure 11 is output power waveform of the operating condition with Fig. 9 when identical, it can be seen that in that case after failure removal
Oscillation of power is larger in a period of time, and transient state energy is larger in transient process, not good for system stability.
Figure 12 is generator rotor angle waveform of the operating condition with Fig. 9 when identical, it can be seen that generator rotor angle constantly increases in that case, causes
Step-out phenomenon, seriously threatens system stability.
Figure 13 is frequency waveform of the operating condition with Fig. 9 when identical, it can be seen that frequency is more than limit value in that case, together
Sample threatens system stability.
Figure 14 is the initial active power reference value P of virtual synchronous machinerefIt is exported greater than virtual synchronous machine in symmetrical short-circuit failure
Active-power Pf, fault section [t1,t2] be [1.5s, 2s] and join the initial active power of virtual synchronous machine after failure starts
Examine value PrefIt is updated to PrefCurrent waveform when '=70kW is compared with Fig. 9, and rush of current is smaller after failure removal in this case,
System stability is preferable when transient state.
Figure 15 is voltage waveform of the operating condition with Figure 14 when identical, is compared with Figure 10, will not be to virtual synchronous in the case of this kind
Generator causes overvoltage impact, and stability is preferable.
Figure 16 is output power waveform of the operating condition with Figure 14 when identical, is compared with Figure 11, in the case of this kind transient state energy compared with
Small, output-power fluctuation is smaller, and system stability is improved.
Figure 17 is generator rotor angle waveform of the operating condition with Figure 14 when identical, knows that generator rotor angle is controlled in the case of this kind with Figure 12 comparison,
Step-out phenomenon will not occur, stability is preferable.
Figure 18 is frequency waveform of the operating condition with Figure 14 when identical, is compared with Figure 13, this kind of situation lower frequency is limiting always
It is worth in range, stability is preferable.
Claims (1)
1. the symmetric fault transient state control method of a kind of meter and virtual synchronous machine saturated characteristic, which is characterized in that the controlling party
Method the following steps are included:
Step 1, setting route symmetrical short-circuit fault point f and fault section [t1,t2]；
Step 2 calculates its rated current virtual value I according to virtual synchronous machine rated capacity SN:
Wherein, UNFor virtual synchronous machine voltage rating virtual value；
Step 3, according to the virtual synchronous machine rated current virtual value I acquired in step 2NSetting virtual synchronous machine output electric current refers to
Enable amplitude limit value IM, IM=(1.1~1.3) IN；
Step 4 exports current-order amplitude limit value I according to the virtual synchronous machine in step 3MIt determines virtual same in symmetrical short-circuit failure
Step machine active power of output Pf:
Pf=3 | IM|2·R1
Wherein, R1For virtual synchronous machine to the equivalent resistance of fault point f；
Step 5, the virtual synchronous machine three-phase of sampling export electric current ia,ib,ic, virtual synchronous machine three-phase output voltage ua,ub,uc, empty
Quasi- synchronous machine filter inductance three-phase current iLa,iLb,iLc, and calculate the active-power P of virtual synchronous machine outputeAnd reactive power
Qe, the active-power P of the virtual synchronous machine outputeAnd reactive power QeCalculating formula be respectively as follows:
Pe=uaia+ubib+ucic
Step 6 sets the initial active power reference value of virtual synchronous machine as Pref, the reference value Q of virtual synchronous machine reactive powerref=
0, virtual synchronous machine built-in potential width before failure is obtained according to the sagging adjusting of the equation of rotor motion of virtual synchronous machine and idle-voltage
Value instruction E and built-in potential phase δ, the calculating formula difference of the virtual synchronous machine built-in potential amplitude instruction E and built-in potential phase δ
Are as follows:
E=Eref-n(Qref-Qe)；
Wherein, ErefFor the reference value of output line voltage, n is the sagging coefficient of reactive power, and J is that the rotation of virtual synchronous machine is used
Amount；ω is the angular speed of virtual synchronous machine output, ω0For rated angular velocity；M is the sagging coefficient of active power；
Compare the initial active power reference value P of virtual synchronous machinerefWith virtual synchronous machine active power of output in symmetrical short-circuit failure
PfNumerical value, if Pref≠Pf, in failure start time t1, by the initial active power reference value P of virtual synchronous machinerefNumerical value more
It is newly that active power reference value is P in virtual synchronous machine failureref' numerical value, wherein in virtual synchronous machine failure active power join
Examine value Pref' numberical range it is defined below:
If Pref< Pf, Pref’∝(Pf, S)；
If Pref> Pf, Pref' ∝ (0, Pf)；
Step 7, the virtual synchronous machine three-phase output voltage u that will be sampled in step 5a,ub,ucCarry out three-phase static coordinate system
To the conversion of two-phase rotating coordinate system, virtual synchronous machine output voltage d axis component u is obtaineddWith output voltage q axis component uq, will walk
The virtual synchronous machine filter inductance three-phase current i sampled in rapid 5La,iLb,iLcThree-phase static coordinate system is carried out to revolve to two-phase
The conversion for turning coordinate system obtains virtual synchronous machine filter wave inductive current d axis component iLdWith filter inductance electric current q axis component iLq；
Virtual synchronous machine output voltage d axis component udWith output voltage q axis component uqExpression formula are as follows:
Virtual synchronous machine filter wave inductive current d axis component iLdWith filter inductance electric current q axis component iLqExpression formula are as follows:
Wherein, t is virtual synchronous machine runing time；
Virtual synchronous machine built-in potential amplitude obtained in step 6 is instructed virtual synchronous machine obtained in E and step 7 defeated by step 8
Voltage d axis component u outdBy d shaft voltage closed-loop control equation, virtual synchronous machine output voltage filter inductance electric current d axis is obtained
Instruction value iLdref；Enable the q axis instruction value u of virtual synchronous machine output voltageqref=0, by virtual synchronous obtained in itself and step 7
Machine output voltage q axis component uqBy q shaft voltage closed-loop control equation, virtual synchronous machine output voltage filter inductance electric current is obtained
Q axis instruction value iLqref, the virtual synchronous machine output voltage filter inductance electric current d axis instruction value iLdrefIt is defeated with virtual synchronous machine
Voltage filter inductive current q axis instruction value i outLqrefExpression formula is respectively as follows:
Wherein, kvpFor voltage close loop proportional controller coefficient, kviFor voltage close loop integral controller coefficient, s is Laplce's calculation
Son；
Step 9, setting virtual synchronous machine filter wave inductive current d axis limits value iLdmaxWith virtual synchronous machine filter wave inductive current q axis
Limits value iLqmax, which makes virtual synchronous machine filter wave inductive current d axis instruction value i obtained in step 8LdrefWith
Virtual synchronous machine filter wave inductive current q axis instruction value iLqrefMeet following constraint:
Virtual synchronous machine filter wave inductive current d axis instruction value iLdrefWith virtual synchronous machine filter wave inductive current q axis instruction value iLqref
After limiter, virtual synchronous machine voltage close loop d axis output valve i is obtainedLdref' and the output of virtual synchronous machine voltage close loop q axis
Value iLqref'；
Step 10, the virtual synchronous machine voltage close loop d axis output valve i for obtaining step 9Ldref' and step 7 obtained in it is virtual same
Walk machine filter wave inductive current d axis component iLdBy d shaft current closed-loop control equation, d axis output signal U is obtainedd；Step 9 is obtained
The virtual synchronous machine voltage close loop q axis output valve i arrivedLqref' and step 7 obtained in virtual synchronous machine filter wave inductive current q axis
Component iLqBy q shaft current closed-loop control equation, q axis output signal U is obtainedq；The d axis output signal UdIt exports and believes with q axis
Number UqAre as follows:
Wherein, kipFor current closed-loop proportional controller coefficient, kiiFor current closed-loop integral controller coefficient；
Step 11, by d axis output signal U obtained in step 10dWith q axis output signal UqIn the built-in potential phase that step 6 obtains
The conversion of two-phase rotating coordinate system to three-phase static coordinate system is done under δ, obtains the three-phase modulations wave of virtual synchronous machine bridge arm voltage
Uma,Umb,Umc, and the driving signal after PWM modulation as IGBT circuit；The three-phase tune of the virtual synchronous machine bridge arm voltage
Wave U processedma,Umb,UmcExpression formula are as follows:
Uma=Udcosδ+Uqsinδ
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| CN109950912B (en) * | 2019-04-03 | 2020-09-01 | 合肥工业大学 | Virtual synchronous generator control method with dynamic flux linkage characteristic simulation |
| CN110535145B (en) * | 2019-08-09 | 2020-07-14 | 广东电网有限责任公司 | Method for calculating voltage sag level of power grid containing STATCOM under symmetric fault |
| FR3101739A1 (en) * | 2019-10-02 | 2021-04-09 | Schneider Electric Industries Sas | Modification of the parameter values of the control law of a generator |
| CN112366957A (en) * | 2021-01-14 | 2021-02-12 | 浙江艾罗网络能源技术股份有限公司 | Impact-resistant grid-connected inverter |
| CN113315122B (en) * | 2021-05-28 | 2022-11-08 | 华北电力大学 | Fault transient current analysis method considering nonlinear characteristics of inverter power supply control system |
| CN113162121B (en) * | 2021-05-31 | 2022-09-13 | 重庆大学 | Power system transient instability risk assessment method with multiple wind power plants |
| CN113452072B (en) * | 2021-06-29 | 2022-04-01 | 华中科技大学 | Method and system for controlling power angle and current voltage of virtual synchronous machine under fault |
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