CN116613751B - Small interference stability analysis method and system for new energy grid-connected system - Google Patents
Small interference stability analysis method and system for new energy grid-connected system Download PDFInfo
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- H—ELECTRICITY
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- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
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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
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- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
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Abstract
The application discloses a small interference stability analysis method and a system of a new energy grid-connected system, wherein the method comprises the following steps: acquiring three-phase voltage and three-phase current at the grid-connected point of the new energy grid-connected system; analyzing the oscillation frequency of the new energy grid-connected system under a three-phase static coordinate system and the three-phase voltage component and the three-phase current component corresponding to the oscillation frequency according to the fast Fourier transformation; calculating the damping ratio of the new energy grid-connected system; calculating the frequency sensitivity and critical sensitivity value of the new energy grid-connected system; and determining a strategy for suppressing broadband oscillation of the new energy grid-connected system according to the frequency sensitivity, the critical sensitivity value and the damping ratio. The method comprises the steps of calculating amplitude sensitivity and damping ratio of broadband oscillation of the new energy grid-connected system, and quantitatively evaluating the broadband oscillation of the new energy grid-connected system, so as to determine a strategy for inhibiting the broadband oscillation of the new energy grid-connected system.
Description
Technical Field
The application belongs to the technical field of new energy grid-connected systems, and particularly relates to a small-interference stability analysis method and system of a new energy grid-connected system.
Background
At present, the broadband oscillation suppression caused by a new energy grid-connected system mainly comprises a grid-connected converter impedance directional remodelling method and an additional device type damping control, wherein the additional device type damping control is divided into active damping control and passive damping control, the active damper is a small-capacity converter similar to an active filter, and the harmonic impedance of a power grid side is changed by detecting and controlling harmonic components of a grid-connected point; the passive damper is a resonance suppression unit formed by a resistance element, a inductance element and a capacitance element which are connected in series at a PCC (power grid) of the new energy grid-connected system, and the unit is equivalent to a large resistance at a resonance frequency point through the matching design of element parameters. The larger the added damping value is, the better the resonance inhibition effect is, but with the increase of the damping value, the power loss of the new energy grid-connected system is improved, the efficiency of the system is reduced, and certain economic loss is brought, so that the damping value is selected to be comprehensively considered, and the damping value cannot be too large or too small.
However, the current research does not provide quantitative broadband oscillation evaluation indexes of the new energy grid-connected system, so that the conventional analysis method is difficult to provide proper oscillation suppression strategy selection for broadband oscillation of the new energy grid-connected system, and proper damping values cannot be added.
Disclosure of Invention
The application provides a small interference stability analysis method and system for a new energy grid-connected system, which are used for solving the technical problem that proper oscillation suppression strategy selection cannot be provided for broadband oscillation of the new energy grid-connected system.
In a first aspect, the present application provides a method for analyzing stability of small interference in a new energy grid-connected system, including:
acquiring three-phase voltage at grid-connected point of new energy grid-connected systemAnd three-phase current->；
Analyzing oscillation frequency of new energy grid-connected system under three-phase static coordinate system according to fast Fourier transformationAnd corresponding to said oscillation frequency +.>Lower three-phase voltage component->And three-phase current component->；
According to the oscillating frequency in a three-phase stationary coordinate systemAnd +.>Corresponding three-phase voltage component->Three-phase current component->Calculating to obtain the damping ratio of the new energy grid-connected system>；
According to the oscillating frequency in a three-phase stationary coordinate systemCalculating broadband oscillation frequency of new energy grid-connected system>And according to the fundamental frequency of the new energy grid-connected system +.>And said broadband oscillation frequency->Calculating to obtain the frequency sensitivity of the new energy grid-connected system>And critical sensitivity value->；
According to the frequency sensitivitySaid critical sensitivity value->And the damping ratio->And determining a strategy for suppressing broadband oscillation of the new energy grid-connected system.
In a second aspect, the present application provides a small-interference stability analysis system of a new energy grid-connected system, including:
the acquisition module is configured to acquire three-phase voltage at grid-connected points of the new energy grid-connected systemAnd three-phase current->；
The analysis module is configured to analyze the oscillation frequency of the new energy grid-connected system under the three-phase static coordinate system according to the fast Fourier transformAnd corresponding oscillation frequency->Lower three-phase voltage componentAnd three-phase current component->；
A first calculation module configured to calculate a first oscillation frequency according to the three-phase stationary coordinate systemAnd +.>Corresponding three-phase voltage component->Three-phase current component/>Calculating to obtain the damping ratio of the new energy grid-connected system>；
A second calculation module configured to calculate a frequency of oscillation in a three-phase stationary coordinate systemCalculating broadband oscillation frequency of new energy grid-connected system>And according to the fundamental frequency of the new energy grid-connected system and the broadband oscillation frequencyCalculating to obtain the frequency sensitivity of the new energy grid-connected system>And critical sensitivity value->；
A determination module configured to determine a frequency sensitivity according to the frequency sensitivitySaid critical sensitivity value->And the damping ratioAnd determining a strategy for suppressing broadband oscillation of the new energy grid-connected system.
In a third aspect, there is provided an electronic device, comprising: the system comprises at least one processor and a memory communicatively connected with the at least one processor, wherein the memory stores instructions executable by the at least one processor to enable the at least one processor to perform the steps of the method for analyzing the small interference stability of the new energy grid-connected system according to any one of the embodiments of the present application.
In a fourth aspect, the present application further provides a computer readable storage medium, on which a computer program is stored, where the program instructions, when executed by a processor, cause the processor to execute the steps of the method for analyzing the stability of small interference of the new energy grid-connected system according to any embodiment of the present application.
The application discloses a small interference stability analysis method and a system for a new energy grid-connected system, which have the following advantages:
the method comprises the steps of calculating amplitude sensitivity and damping ratio of broadband oscillation of the new energy grid-connected system, and quantitatively evaluating the broadband oscillation of the new energy grid-connected system, so as to determine a strategy for inhibiting the broadband oscillation of the new energy grid-connected system.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for the description of the embodiments will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present application, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a flow chart of a method for analyzing the stability of small interference of a new energy grid-connected system according to an embodiment of the present application;
FIG. 2 is a schematic diagram showing a method for suppressing broadband oscillation of a new energy grid-connected system according to an embodiment of the present application;
FIG. 3 is a diagram of a new energy grid-connected system according to an embodiment of the present application;
FIG. 4 is a waveform diagram of the voltage and current at the secondary side of the transformer for providing a grid-tie point voltage for wideband oscillation event 1 according to one embodiment of the present application;
FIG. 5 is a diagram showing FFT analysis results of data obtained by measuring the grid-connected point phase voltage of the broadband oscillation event 1 on the secondary side of the transformer according to an embodiment of the present application;
FIG. 6 is a diagram showing FFT analysis results of data obtained by measuring the grid-connected point phase current of the broadband oscillation event 1 on the secondary side of the transformer according to an embodiment of the present application;
FIG. 7 is a block diagram illustrating a system for analyzing stability of small interference of a new energy grid-connected system according to an embodiment of the present application;
fig. 8 is a schematic structural diagram of an electronic device according to an embodiment of the present application.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present application more apparent, the technical solutions of the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application, and it is apparent that the described embodiments are some embodiments of the present application, but not all embodiments of the present application. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.
Referring to fig. 1, a flowchart of a method for analyzing the stability of small interference of a new energy grid-connected system according to the present application is shown.
As shown in fig. 1, the method for analyzing the stability of the small interference of the new energy grid-connected system specifically includes the following steps:
step S101, obtaining three-phase voltage at grid-connected point of new energy grid-connected systemAnd three-phase current。
In the step, three-phase voltages at grid connection points of the new energy grid connection system generating broadband oscillation are measured and recorded by utilizing a voltage sensor and a current sensorAnd three-phase current->。
Step S102, analyzing the oscillation frequency of the new energy grid-connected system under a three-phase static coordinate system according to the fast Fourier transformAnd corresponding to said oscillation frequency +.>Lower three-phase voltage component->And three-phase current component->。
In this step, for three-phase voltagesRespectively performing fast Fourier transform analysis to find out three-phase voltage component (i.e. the three-phase voltage component (i) with the largest amplitude except the fundamental frequency) in a-phase voltage, b-phase voltage and c-phase voltage>And the oscillation frequency corresponding to the three-phase stationary coordinate system +.>The method comprises the steps of carrying out a first treatment on the surface of the For the three-phase current->Performing fast Fourier transform analysis to find out three-phase current components with maximum amplitude except fundamental frequency in a-phase current, b-phase current and c-phase current。
Step S103, according to the oscillation frequency in the three-phase stationary coordinate systemAnd with the oscillation frequencyCorresponding three-phase voltage component->Three-phase current component->Calculating to obtain the damping ratio of the new energy grid-connected system>。
In this step, the frequency of oscillation is determined according toCorresponding three-phase voltage component->Three-phase current component->Calculating impedance scores of new energy grid-connected system in three-phase static coordinate systemWherein the impedance score +.>The expression of (2) is:
，
in the method, in the process of the application,impedance score of new energy grid-connected system under phase a,/for new energy grid-connected system>Impedance score of new energy grid-connected system under phase b, +.>Impedance score of new energy grid-connected system under c phase, +.>Resistance value of new energy grid-connected system under phase a, < >>Reactance value of new energy grid-connected system under a three phases +.>Resistance value of new energy grid-connected system under phase b +.>Reactance value of new energy grid-connected system under b three phases +.>The resistance value of the new energy grid-connected system under the phase c is adopted,reactance value of new energy grid-connected system under c three phases, < >>Is the unit of imaginary number;
according to impedance values in a three-phase stationary coordinate systemCalculating impedance value of new energy grid-connected systemWherein, calculating the impedance value of the new energy grid-connected system +.>The expression of (2) is:
，
in the method, in the process of the application,resistance value of new energy grid-connected system, < +.>The reactance value of the new energy grid-connected system is obtained;
calculating damping ratio of new energy grid-connected systemWherein the damping ratio is calculated>The expression of (2) is:
。
step S104, according to the oscillation frequency in the three-phase stationary coordinate systemCalculating broadband oscillation frequency of new energy grid-connected system>And according to the fundamental frequency of the new energy grid-connected system +.>And said broadband oscillation frequency->Calculating to obtain the frequency sensitivity of the new energy grid-connected system>And critical sensitivity value->。
In this step, according to the oscillation frequency in the three-phase stationary coordinate systemBroadband oscillation of new energy grid-connected systemFrequency->Wherein, calculate the broadband oscillation frequency +.>The expression of (2) is:
，
in the method, in the process of the application,the oscillation frequency of the new energy grid-connected system under the phase a is +.>The oscillation frequency of the new energy grid-connected system under phase b is +.>The oscillation frequency of the new energy grid-connected system under the phase c is used;
according to the fundamental frequency and broadband oscillation frequency of the new energy grid-connected systemCalculating to obtain the frequency sensitivity of the new energy grid-connected system>Wherein the frequency sensitivity is calculated>The expression of (2) is:
，
，
，
in the method, in the process of the application,、/>frequency sensitivity +.>First coefficient and second coefficient of +.>Fundamental frequency of new energy grid-connected system, +.>The switching frequency of the grid-connected converter is set;
fundamental frequency according to new energy grid-connected systemCalculating critical sensitivity value +.>Wherein, calculating critical sensitivity valueThe expression of (2) is:
。
step S105, according to the frequency sensitivitySaid critical sensitivity value->And the damping ratio->And determining a strategy for suppressing broadband oscillation of the new energy grid-connected system.
At the bookIn the step, if the frequency sensitivity isCritical sensitivity value +.>Then passive damping control is adopted, and the damping ratio is +.>The larger the absolute value of (2), the larger the damping value of the passive damping control; if the frequency sensitivity is->Critical sensitivity value->And damping ratio->Negative, active damping control is used, and the damping ratio is +.>The larger the absolute value of (2), the larger the damping value of the active damping control; if the frequency sensitivity is->Critical sensitivity value->And damping ratio->Positive, then harmonic failure.
In summary, the method of the application realizes quantitative evaluation of the broadband oscillation of the new energy grid-connected system by calculating the amplitude sensitivity and the damping ratio of the broadband oscillation of the new energy grid-connected system, and is used for determining the inhibition strategy of the broadband oscillation of the new energy grid-connected system.
FIG. 3 shows a topology of a new energy grid-connected system with fundamental frequency of the new energy grid-connected system50Hz, the switching frequency of the grid-connected converter is +.>Is 2kHz. Main monitoring new forms of energy grid-connected system grid-connected point phase voltage +.>Phase current->By calculating the frequency sensitivity and damping ratio of the broadband oscillation evaluation index of the new energy grid-connected system, and comparing with FIG. 2, the method for inhibiting the broadband oscillation of the new energy grid-connected system can be determined.
Fig. 4 shows waveforms of the grid-tie point voltage, current measured on the secondary side of the transformer for wideband oscillation event 1. Three-phase voltage of the grid-connected point can be obtained by utilizing the voltage sensor and the current sensorThree-phase current->Data on the secondary side of the transformer. FIG. 5 shows the sampled three-phase voltages +.>The result of FFT analysis can find out the voltage component +.f with the largest amplitude except the fundamental frequency in the a-phase voltage, b-phase voltage and c-phase voltage>=0.3-j84.5V，/>=-73.2+j42.3V，/>=73.2+j42.3v and the corresponding oscillation frequencies are +.>=55Hz，/>=55Hz，=55hz. FIG. 6 shows the sampling of three-phase currents +.>The result of FFT analysis can find out the current component +.f with the largest amplitude except the fundamental frequency in the a-phase current, b-phase current and c-phase current>=667.1+j898.6A，/>=437.6-j1030.5A，/>=-1107.8+j134.2A。
Calculating oscillation frequency of broadband oscillation of new energy grid-connected systemThe calculation formula is as follows:
，
then calculating broadband oscillation evaluation index-frequency sensitivity of new energy grid-connected systemThe calculation formula is as follows:
，
will oscillate the frequencySubstitution of =55hz, can be calculated +.>=0.0209。
Frequency sensitivity thresholdThe calculation mode is as follows:
，
=0.0209</>because of the fact that the frequency band oscillation of the new energy grid-connected system is not easy to be restrained in the state of being=0.50, passive damping control is needed to be applied.
Respectively calculating impedance values of the new energy grid-connected system under abc three phases:
，
then, calculating an impedance value Z of the new energy grid-connected system, wherein the impedance value Z is as follows:
，
wherein r is the resistance value of the new energy grid-connected system, and x is the reactance value of the new energy grid-connected system.
Finally, calculating the damping ratio of the new energy grid-connected systemThe following is shown:
，
damping ratio of new energy grid-connected systemThe value range of (C) is [ -1,1]Calculated +.>The negative value of = -0.80 indicates that the new energy grid-connected system is unstable, which is consistent with the oscillation waveform of the new energy grid-connected system shown in fig. 4.
In summary, the frequency sensitivity of the new energy grid-connected system under the event is calculated to be 0.0209 and smaller thanAnd damping ratio->Is-0.8, so that the new energy grid-connected system in the state is controlled by passive damping and the damping ratio is +.>The damping value is selected to be-0.8 and close to-1, and the damping value is selected to be larger.
Referring to fig. 7, a block diagram of a small-interference stability analysis system of a new energy grid-connected system according to the present application is shown.
As shown in fig. 7, the small-disturbance stability analysis system 200 includes an acquisition module 210, an analysis module 220, a first calculation module 230, a second calculation module 240, and a determination module 250.
Wherein, the obtaining module 210 is configured to obtain the three-phase voltage at the grid-connected point of the new energy grid-connected systemAnd three-phase current->The method comprises the steps of carrying out a first treatment on the surface of the An analysis module 220 configured to analyze the oscillation frequency +_of the new energy grid-connected system in the three-phase stationary coordinate system according to the fast Fourier transform>And corresponding oscillation frequency->Lower three-phase voltage component->And three-phase current component->The method comprises the steps of carrying out a first treatment on the surface of the A first calculation module 230 configured to determine the oscillation frequency in the three-phase stationary coordinate system>And +.>Corresponding three-phase voltage component->Three-phase current component->Calculating to obtain damping ratio of new energy grid-connected systemThe method comprises the steps of carrying out a first treatment on the surface of the A second calculation module 240 configured to determine the oscillation frequency in the three-phase stationary coordinate system>Calculating broadband oscillation frequency of new energy grid-connected system>And according to the fundamental frequency of the new energy grid-connected system and the broadband oscillation frequency +.>Calculating to obtain the frequency sensitivity of the new energy grid-connected system>And critical sensitivity value->The method comprises the steps of carrying out a first treatment on the surface of the A determination module 250 configured to determine the frequency sensitivity>Said critical sensitivity value->And the damping ratio->And determining a strategy for suppressing broadband oscillation of the new energy grid-connected system.
It should be understood that the modules depicted in fig. 7 correspond to the various steps in the method described with reference to fig. 1. Thus, the operations and features described above for the method and the corresponding technical effects are equally applicable to the modules in fig. 7, and are not described here again.
In other embodiments, embodiments of the present application further provide a computer readable storage medium having stored thereon a computer program, the program instructions, when executed by a processor, cause the processor to perform the method for small-interference stability analysis in any of the method embodiments described above;
as one embodiment, the computer-readable storage medium of the present application stores computer-executable instructions configured to:
acquiring three-phase voltage at grid-connected point of new energy grid-connected systemAnd three-phase current->；
Analyzing oscillation frequency of new energy grid-connected system under three-phase static coordinate system according to fast Fourier transformationAnd corresponding to said oscillation frequency +.>Lower three-phase voltage component->And three-phase current component->；
According to the oscillating frequency in a three-phase stationary coordinate systemAnd +.>Corresponding three-phase voltage component->Three-phase current component->Calculating to obtain the damping ratio of the new energy grid-connected system>；
According to the oscillating frequency in a three-phase stationary coordinate systemCalculating broadband oscillation frequency of new energy grid-connected system>And according to the fundamental frequency of the new energy grid-connected system +.>And said broadband oscillation frequency->Calculating to obtain the frequency sensitivity of the new energy grid-connected system>And critical sensitivity value->；
According to the frequency sensitivitySaid critical sensitivity value->And the damping ratio->And determining a strategy for suppressing broadband oscillation of the new energy grid-connected system.
The computer readable storage medium may include a storage program area and a storage data area, wherein the storage program area may store an operating system, at least one application program required for a function; the storage data area may store data created from the use of the small-disturbance stability analysis system, etc. In addition, the computer-readable storage medium may include high-speed random access memory, and may also include memory, such as at least one magnetic disk storage device, flash memory device, or other non-volatile solid-state storage device. In some embodiments, the computer readable storage medium optionally includes memory remotely located with respect to the processor, which may be connected to the small-disturbance stability analysis system via a network. Examples of such networks include, but are not limited to, the internet, intranets, local area networks, mobile communication networks, and combinations thereof.
Fig. 8 is a schematic structural diagram of an electronic device according to an embodiment of the present application, as shown in fig. 8, where the device includes: a processor 310 and a memory 320. The electronic device may further include: an input device 330 and an output device 340. The processor 310, memory 320, input device 330, and output device 340 may be connected by a bus or other means, for example in fig. 8. Memory 320 is the computer-readable storage medium described above. The processor 310 executes various functional applications of the server and data processing by running non-volatile software programs, instructions and modules stored in the memory 320, i.e., implements the method of small-interference stability analysis described above in the method embodiments. The input device 330 may receive input numeric or character information and generate key signal inputs related to user settings and function control of the small disturbance stability analysis system. The output device 340 may include a display device such as a display screen.
The electronic equipment can execute the method provided by the embodiment of the application, and has the corresponding functional modules and beneficial effects of the execution method. Technical details not described in detail in this embodiment may be found in the methods provided in the embodiments of the present application.
As an implementation manner, the electronic device is applied to a small interference stability analysis system, and is used for a client, and includes: at least one processor; and a memory communicatively coupled to the at least one processor; wherein the memory stores instructions executable by the at least one processor, the instructions being executable by the at least one processor to enable the at least one processor to:
acquiring three-phase voltage at grid-connected point of new energy grid-connected systemAnd three-phase current->；
Analyzing oscillation frequency of new energy grid-connected system under three-phase static coordinate system according to fast Fourier transformationAnd corresponding to said oscillation frequency +.>Lower three-phase voltage component->And three-phase current component->；
According to the oscillating frequency in a three-phase stationary coordinate systemAnd +.>Corresponding three-phase voltage component->Three-phase current component->Calculating to obtain the damping ratio of the new energy grid-connected system>；
According to the oscillating frequency in a three-phase stationary coordinate systemCalculating broadband oscillation frequency of new energy grid-connected system>And according to the fundamental frequency of the new energy grid-connected system +.>And said broadband oscillation frequency->Calculating to obtain the frequency sensitivity of the new energy grid-connected system>And critical sensitivity value->；
According to the frequency sensitivitySaid critical sensitivity value->And the damping ratio->And determining a strategy for suppressing broadband oscillation of the new energy grid-connected system.
From the above description of the embodiments, it will be apparent to those skilled in the art that the embodiments may be implemented by means of software plus necessary general hardware platforms, or of course may be implemented by means of hardware. Based on such understanding, the foregoing technical solutions may be embodied essentially or in part in the form of a software product, which may be stored in a computer-readable storage medium, such as a ROM/RAM, a magnetic disk, an optical disk, etc., including several instructions to cause a computer device (which may be a personal computer, a server, or a network device, etc.) to perform the various embodiments or methods of some parts of the embodiments.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present application, and are not limiting; although the application has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present application.
Claims (8)
1. The small interference stability analysis method of the new energy grid-connected system is characterized by comprising the following steps of:
acquiring three-phase voltage u at grid-connected point of new energy grid-connected system a 、u b 、u c And three-phase current i a 、i b 、i c ；
Analyzing oscillation frequency f of new energy grid-connected system under three-phase static coordinate system according to fast Fourier transformation a 、f b 、f c And correspond to the oscillation frequency f a 、f b 、f c Lower three-phase voltage component u fa 、u fb 、u fc And three (III)Phase current component i fa 、i fb 、i fc ；
According to the oscillation frequency f in a three-phase stationary coordinate system a 、f b 、f c And with the oscillation frequency f a 、f b 、f c Corresponding three-phase voltage component u fa 、u fb 、u fc Three-phase current component i fa 、i fb 、i fc Calculating to obtain a damping ratio xi of the new energy grid-connected system;
according to the oscillation frequency f in a three-phase stationary coordinate system a 、f b 、f c Calculating the broadband oscillation frequency f of the new energy grid-connected system, and according to the fundamental frequency f of the new energy grid-connected system 0 And the broadband oscillation frequency f is calculated to obtain the frequency sensitivity f of the new energy grid-connected system sen And critical sensitivity value f 0 ' wherein, the frequency sensitivity f of the new energy grid-connected system is calculated sen And a critical sensitivity value f' 0 Comprising the following steps:
according to the oscillation frequency f in a three-phase stationary coordinate system a 、f b 、f c Calculating a broadband oscillation frequency f of a new energy grid-connected system, wherein the expression for calculating the broadband oscillation frequency f is as follows:
wherein f a The oscillation frequency of the new energy grid-connected system under the phase a, f b The oscillation frequency of the new energy grid-connected system under the phase b, f c The oscillation frequency of the new energy grid-connected system under the phase c is used;
calculating the frequency sensitivity f of the new energy grid-connected system according to the fundamental frequency of the new energy grid-connected system and the broadband oscillation frequency f sen Wherein the frequency sensitivity f is calculated sen The expression of (2) is:
wherein k is 1 、k 2 Respectively the frequency sensitivity f sen First coefficient and second coefficient of f 0 Fundamental frequency f of new energy grid-connected system s The switching frequency of the grid-connected converter is set;
according to fundamental frequency f of new energy grid-connected system 0 Calculating critical sensitivity value f' 0 Wherein the critical sensitivity value f 'is calculated' 0 The expression of (2) is:
f′ 0 ＝k 1 ×(0.707×f 0 -f 0 )×(0.707×f 0 +f 0 )；
according to the frequency sensitivity f sen The critical sensitivity value f 0 And' and the damping ratio xi determine a strategy for suppressing broadband oscillation of the new energy grid-connected system.
2. The method for analyzing the stability of small interference of a new energy grid-connected system according to claim 1, wherein the method for acquiring the three-phase voltage u at the grid-connected point of the new energy grid-connected system is characterized in that a 、u b 、u c And three-phase current i a 、i b 、i c Comprising the following steps:
acquiring three-phase voltage u at grid-connected point of new energy grid-connected system with broadband oscillation a 、u b 、u c And three-phase current i a 、i b 、i c 。
3. The method for analyzing the stability of the small interference of the new energy grid-connected system according to claim 1, wherein the new energy grid-connected system is analyzed in a three-phase stationary coordinate system according to the fast fourier transformFrequency f of oscillation a 、f b 、f c And correspond to the oscillation frequency f a 、f b 、f c Lower three-phase voltage component u fa 、u fb 、u fc And three-phase current component i fa 、i fb 、i fc Comprising the following steps:
for the three-phase voltage u a 、u b 、u c Respectively performing fast Fourier transform analysis to find out three-phase voltage component u with maximum amplitude except fundamental frequency in a-phase voltage, b-phase voltage and c-phase voltage fa 、u fb 、u fc Corresponding to the oscillation frequency f in a three-phase stationary coordinate system a 、f b 、f c ；
For the three-phase current i a 、i b 、i c Performing fast Fourier transform analysis to find out three-phase current component i with maximum amplitude except fundamental frequency in a-phase current, b-phase current and c-phase current fa 、i fb 、i fc 。
4. The method for analyzing the stability of small interference of a new energy grid-connected system according to claim 1, wherein the method is characterized in that the method is based on the oscillation frequency f in a three-phase stationary coordinate system a 、f b 、f c And with the oscillation frequency f a 、f b 、f c Corresponding three-phase voltage component u fa 、u fb 、u fc Three-phase current component i fa 、i fb 、i fc The damping ratio xi of the new energy grid-connected system obtained by calculation comprises the following steps:
according to the frequency f of oscillation a 、f b 、f c Corresponding three-phase voltage component u fa 、u fb 、u fc Three-phase current component i fa 、i fb 、i fc Calculating impedance score Z of new energy grid-connected system under three-phase static coordinate system a 、Z b 、Z c Wherein the impedance score Z in the three-phase stationary coordinate system is calculated a 、Z b 、Z c The expression of (2) is:
wherein Z is a Z is the impedance score of the new energy grid-connected system under phase a b Z is the impedance score of the new energy grid-connected system under phase b c The impedance score of the new energy grid-connected system under the phase c is r a The resistance value of the new energy grid-connected system under the phase a, x a The reactance value of the new energy grid-connected system under the phase a, r b The resistance value of the new energy grid-connected system under the phase b, x b The reactance value of the new energy grid-connected system under the phase b, r c The resistance value of the new energy grid-connected system under the phase c, x c The reactance value of the new energy grid-connected system under the phase c is represented by j, which is the unit of an imaginary part;
according to the impedance value Z in the three-phase stationary coordinate system a 、Z b 、Z c Calculating an impedance value Z of the new energy grid-connected system, wherein the expression for calculating the impedance value Z of the new energy grid-connected system is as follows:
wherein r is the resistance value of the new energy grid-connected system, and x is the reactance value of the new energy grid-connected system;
calculating a damping ratio xi of a new energy grid-connected system, wherein an expression for calculating the damping ratio xi is as follows:
5. the method for analyzing the stability of small interference of a new energy grid-connected system according to claim 1, wherein the frequency sensitivity f is based on sen The critical sensitivity value f 0 The damping ratio xi and the strategy for determining the broadband oscillation suppression of the new energy grid-connected system comprise the following steps:
if the frequency sensitivity f sen Critical sensitivity value f%' 0 The passive damping control is adopted, and the larger the absolute value of the damping ratio xi is, the larger the damping value of the passive damping control is;
if the frequency sensitivity f sen Critical sensitivity value f' 0 And the damping ratio xi is negative, then active damping control is adopted, and the larger the absolute value of the damping ratio xi is, the larger the damping value of the active damping control is;
if the frequency sensitivity f sen Critical sensitivity value f' 0 And the damping ratio xi is positive, then it is a harmonic fault.
6. The utility model provides a little interference stability analysis system of new forms of energy grid-connected system which characterized in that includes:
the acquisition module is configured to acquire three-phase voltage u at grid-connected point of new energy grid-connected system a 、u b 、u c And three-phase current i a 、i b 、i c ；
The analysis module is configured to analyze the oscillation frequency f of the new energy grid-connected system under the three-phase static coordinate system according to the fast Fourier transform a 、f b 、f c And corresponding oscillation frequency f a 、f b 、f c Lower three-phase voltage component u fa 、u fb 、u fc And three-phase current component i fa 、i fo 、i fc ；
A first calculation module configured to calculate a first oscillation frequency according to the three-phase stationary coordinate system a 、f b 、f c And with the oscillation frequency f a 、f b 、f c Corresponding three-phase voltage component u fa 、u fb 、u fc Three-phase current component i fa 、i fo 、i fc Calculating to obtain a damping ratio xi of the new energy grid-connected system;
a second calculation module configured to calculate a frequency f according to the oscillation frequency in the three-phase stationary coordinate system a 、f b 、f c Calculating the broadband oscillation frequency f of the new energy grid-connected system, and combining according to the new energyCalculating the fundamental frequency of the grid system and the broadband oscillation frequency f to obtain the frequency sensitivity f of the new energy grid-connected system sen And critical sensitivity value f 0 ' wherein, the frequency sensitivity f of the new energy grid-connected system is calculated sen And a critical sensitivity value f' 0 Comprising the following steps:
according to the oscillation frequency f in a three-phase stationary coordinate system a 、f b 、f c Calculating a broadband oscillation frequency f of a new energy grid-connected system, wherein the expression for calculating the broadband oscillation frequency f is as follows:
wherein f a The oscillation frequency of the new energy grid-connected system under the phase a, f b The oscillation frequency of the new energy grid-connected system under the phase b, f c The oscillation frequency of the new energy grid-connected system under the phase c is used;
calculating the frequency sensitivity f of the new energy grid-connected system according to the fundamental frequency of the new energy grid-connected system and the broadband oscillation frequency f sen Wherein the frequency sensitivity f is calculated sen The expression of (2) is:
wherein k is 1 、k 2 Respectively the frequency sensitivity f sen First coefficient and second coefficient of f 0 Fundamental frequency f of new energy grid-connected system s The switching frequency of the grid-connected converter is set;
according to fundamental frequency f of new energy grid-connected system 0 Calculating critical sensitivity value f' 0 Wherein the critical sensitivity value f 'is calculated' 0 The expression of (2) is:
f′ 0 ＝k 1 ×(0.707×f 0 -f 0 )×(0.707×f 0 +f 0 )；
a determination module configured to determine the frequency sensitivity f sen The critical sensitivity value f' 0 And determining a strategy for inhibiting broadband oscillation of the new energy grid-connected system by the damping ratio xi.
7. An electronic device, comprising: at least one processor, and a memory communicatively coupled to the at least one processor, wherein the memory stores instructions executable by the at least one processor to enable the at least one processor to perform the method of any one of claims 1 to 5.
8. A computer readable storage medium, on which a computer program is stored, characterized in that the program, when being executed by a processor, implements the method of any one of claims 1 to 5.
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