CN112765932A - Method and device for analyzing influence of SVG on double-fed grid-connected system - Google Patents

Method and device for analyzing influence of SVG on double-fed grid-connected system Download PDF

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CN112765932A
CN112765932A CN202110103167.0A CN202110103167A CN112765932A CN 112765932 A CN112765932 A CN 112765932A CN 202110103167 A CN202110103167 A CN 202110103167A CN 112765932 A CN112765932 A CN 112765932A
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谢欢
辛焕海
艾力西尔·亚尔买买提
李善颖
吴涛
梁浩
李长宇
曹天植
黄天啸
严乙桉
辛光明
罗婧
刘瑛琳
郝婧
王炳辉
陈瑞
刘军娜
檀政
徐鹏
史扬
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State Grid Corp of China SGCC
North China Electric Power Research Institute Co Ltd
Electric Power Research Institute of State Grid Jibei Electric Power Co Ltd
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North China Electric Power Research Institute Co Ltd
Electric Power Research Institute of State Grid Jibei Electric Power Co Ltd
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Abstract

The invention discloses a method and a device for analyzing the influence of SVG on a double-fed grid-connected system, wherein the method comprises the following steps: obtaining an equivalent model of interaction of the SVG and a double-fed grid-connected system; simplifying the equivalent model into a single-input single-output equivalent complex circuit model; obtaining an influence factor index of the SVG additional impedance on the system oscillation mode according to the single-input single-output equivalent complex circuit model; and determining the influence of the SVG on the doubly-fed grid-connected system according to the influence factor index. The invention provides a method for effectively analyzing the influence of SVG on a double-fed grid-connected system.

Description

Method and device for analyzing influence of SVG on double-fed grid-connected system
Technical Field
The invention relates to the field of stability analysis of a double-fed grid-connected system, in particular to a method and a device for analyzing the influence of SVG on the double-fed grid-connected system.
Background
Doubly-fed equipment such as doubly-fed pumped storage equipment and doubly-fed wind turbine generator system, there are many time scale control links and the quick control characteristic of power electronic drive equipment, and along with doubly-fed equipment's wide use, make between cluster doubly-fed equipment and the electric wire netting and with the operation control intercoupling between the adjacent power electronic drive equipment and influence outstanding, doubly-fed equipment passes through the converter and links to each other with the backbone system rack, the stable problem of system voltage is outstanding, the oscillation problem of converter grid-connected system can generally carry out the analysis from the small interference angle, the method mainly has two kinds: a characteristic root analysis method based on state space and an impedance analysis method based on frequency domain theory. The characteristic root analysis method depends on detailed models and parameters of a converter and a power grid, and is difficult to adapt to large-scale double-fed equipment grid-connected analysis. In comparison, the impedance analysis method considers the converter and the power grid as two independent subsystems, and judges the stability of the system according to whether the impedance matrixes of the two subsystems meet the Nyquist stability criterion. The impedance matrix used by the impedance method can be obtained through measurement, that is, the stability of the system can be quantitatively analyzed by measuring the characteristics outside the ports of the converter and the power grid, so that the method has attracted extensive attention.
By adopting the SVG (static var generator), reactive compensation can be carried out on the double-fed grid-connected system, so that voltage support can be provided for the system, and the SVG has the characteristics of strong adjustability, high response speed and high reliability. The control strategy of the currently used SVG (static var generator) mainly adopts constant reactive power control or constant alternating voltage control. However, no clear method is available for analyzing the stability of the double-fed equipment set and the grid-connected system of the SVG. In addition, the influence of the SVG on the grid-connected system of the double-fed device is not theoretically analyzed and explained, so that the small interference stability of the double-fed device and the SVG interactive system is difficult to evaluate.
Disclosure of Invention
The invention provides a method and a device for analyzing the influence of SVG on a double-fed grid-connected system, aiming at solving at least one technical problem in the background technology.
In order to achieve the above object, according to an aspect of the present invention, there is provided a method for analyzing an influence of SVG on a doubly-fed grid-connected system, the method including:
obtaining an equivalent model of interaction of the SVG and a double-fed grid-connected system;
simplifying the equivalent model into a single-input single-output equivalent complex circuit model;
obtaining an influence factor index of the SVG additional impedance on the system oscillation mode according to the single-input single-output equivalent complex circuit model;
and determining the influence of the SVG on the doubly-fed grid-connected system according to the influence factor index.
Optionally, the equivalent model is constructed by a generalized impedance and an equivalent source-pair complex circuit analysis method in small interference stability analysis.
Optionally, determining the influence of the SVG on the doubly-fed grid-connected system according to the influence factor index includes:
and determining the influence of the SVG on the stability and the oscillation frequency of the doubly-fed grid-connected system according to the influence factor index.
Optionally, determining the influence of the SVG on the stability and the oscillation frequency of the doubly-fed grid-connected system according to the influence factor index includes:
if the real part of the influence factor index is positive, determining to add SVG to reduce the stability of the double-fed grid-connected system;
and if the real part of the influence factor index is negative, determining to add the SVG so as to improve the stability of the double-fed grid-connected system.
Optionally, determining the influence of the SVG on the stability and the oscillation frequency of the doubly-fed grid-connected system according to the influence factor index includes:
if the imaginary part of the influence factor index is positive, determining to add SVG to improve the oscillation frequency of the doubly-fed grid-connected system;
and if the imaginary part of the influence factor index is negative, determining to add the SVG to reduce the oscillation frequency of the doubly-fed grid-connected system.
Optionally, the resonance zero of the single-input single-output equivalent complex circuit model is a characteristic root of the equivalent model.
In order to achieve the above object, according to another aspect of the present invention, there is provided an apparatus for analyzing an influence of SVG on a doubly-fed grid-connected system, the apparatus comprising:
the equivalent model acquisition unit is used for acquiring an equivalent model of interaction of the SVG and the doubly-fed grid-connected system;
the model transformation unit is used for simplifying the equivalent model into a single-input single-output equivalent complex circuit model;
the influence factor index determining unit is used for obtaining the influence factor index of the SVG additional impedance on the system oscillation mode according to the single-input single-output equivalent complex circuit model;
and the influence analysis unit is used for determining the influence of the SVG on the double-fed grid-connected system according to the influence factor index.
In order to achieve the above object, according to another aspect of the present invention, there is also provided a computer device, including a memory, a processor and a computer program stored on the memory and executable on the processor, the processor implementing the steps in the above method for analyzing the influence of SVG on a doubly-fed grid-connected system when executing the computer program.
In order to achieve the above object, according to another aspect of the present invention, there is also provided a computer readable storage medium storing a computer program which, when executed in a computer processor, implements the steps in the above method for analyzing the influence of SVG on a doubly-fed grid-connected system.
The invention has the beneficial effects that: according to the method, the equivalent model is simplified into the single-input single-output equivalent complex circuit model, the influence factor index of the SVG additional impedance on the system oscillation mode is further obtained according to the single-input single-output equivalent complex circuit model, and finally the influence of the SVG on the double-fed grid-connected system can be determined according to the influence factor index, so that the influence of the SVG on the double-fed grid-connected system is effectively analyzed.
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In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts. In the drawings:
FIG. 1 is a flowchart of a method for analyzing the influence of SVG on a doubly-fed grid-connected system according to an embodiment of the present invention;
FIG. 2 is a flowchart of determining the influence of SVG on the stability of a doubly-fed grid-connected system according to an embodiment of the present invention;
FIG. 3 is a flowchart of determining the influence of SVG on the oscillation frequency of a doubly-fed grid-connected system according to an embodiment of the present invention;
FIG. 4 is a block diagram of a device for analyzing the influence of SVG on a doubly-fed grid-connected system according to an embodiment of the present invention;
FIG. 5 is an equivalent primary-dual complex circuit of the interaction of the SVG and the double-fed grid-connected system of the present invention;
FIG. 6 is a Thevenin equivalent diagram of a converter and SVG interactive system in simulation verification according to an embodiment of the present invention;
FIG. 7 is a schematic diagram of a computer apparatus according to an embodiment of the present invention.
Detailed Description
In order to make the technical solutions of the present invention better understood, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
As will be appreciated by one skilled in the art, embodiments of the present invention may be provided as a method, system, or computer program product. Accordingly, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
It should be noted that the terms "comprises" and "comprising," and any variations thereof, in the description and claims of the present invention and the above-described drawings, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.
It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict. The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings.
The invention provides a method for analyzing the influence of SVG on a double-fed grid-connected system based on complex circuit modal power, which is used for analyzing the influence of SVG on the stability and oscillation mode of the double-fed grid-connected system.
Fig. 1 is a flowchart of a method for analyzing an influence of SVG on a doubly-fed grid-connected system according to an embodiment of the present invention, and as shown in fig. 1, the method for analyzing an influence of SVG on a doubly-fed grid-connected system according to the embodiment includes steps S101 to S104.
And S101, obtaining an equivalent model of interaction of the SVG and the doubly-fed grid-connected system.
In the embodiment of the invention, the double-fed grid-connected system consists of double-fed equipment, a converter and an alternating current power grid, wherein the double-fed equipment can be double-fed pumping and storage equipment or a double-fed wind turbine generator set, and the double-fed equipment is connected with the alternating current power grid through the converter to form the double-fed grid-connected system.
SVG (static var generator) can carry out reactive compensation to the double-fed system that is incorporated into the power networks to can provide voltage support for the system, SVG has strong, the fast and high characteristics of reliability of adjustable ability, response speed. The control strategy of the currently used SVG (static var generator) mainly adopts constant reactive power control or constant alternating voltage control.
In one embodiment of the invention, the equivalent model is constructed by an analysis method of generalized impedance and equivalent source-pair complex circuit in small disturbance stability analysis.
And S102, simplifying the equivalent model into a single-input single-output equivalent complex circuit model.
In an embodiment of the present invention, the step may specifically simplify the equivalent model into a single-input single-output equivalent complex circuit model through linear transformation.
In an embodiment of the present invention, a single-input single-output equivalent complex circuit model (equivalent complex circuit) of the present invention can be shown in fig. 5, the equivalent complex circuit can represent the stability of a converter and SVG interactive system, the parallel generalized impedance added in the system equivalent complex circuit can be regarded as the additional impedance of the SVG to the original converter grid-connected system, and the equivalent complex circuit has stability equivalence with the original double-feed and SVG interactive system, that is, the resonance zero point of the single-input single-output equivalent complex circuit model is the characteristic root of the equivalent model.
In FIG. 5, YPR_v,YDR_vThe method comprises the following steps of respectively providing primary and dual generalized admittances for a rotor-side converter of the doubly-fed equipment; y isPG_v,YDG_vThe method comprises the following steps of respectively providing a primary generalized admittance and a dual generalized admittance of a grid-side converter of the double-fed equipment; delta YP_sys,ΔYD_sysRespectively an additional original admittance and a dual admittance of the SVG to the system; y isP_net,YD_netThe method comprises the following steps of respectively obtaining primary and dual generalized admittances of an alternating current network; y isPRD_vMutual admittance of a double-fed equipment rotor side converter between a node P and a node D; y isPGD_vMutual admittance of the doubly-fed equipment grid-side converter between a node P and a node D; delta YPD_vMutual admittance of the SVG between the node P and the node D; s represents the laplacian operator; y iss11，Ys22A polar coordinate impedance model expression of the SVG; y isv1，Yv4The method comprises the following steps of (1) obtaining a polar coordinate impedance model expression of a doubly-fed equipment grid-side converter; y isg1，Yg4The method comprises the following steps of (1) obtaining a polar coordinate impedance model expression of a doubly-fed equipment rotor-side converter; cfA filter capacitor matrix is arranged at the outlet of the converter; b is a node admittance matrix of the AC network system after node compression; omega0And synchronizing the angular frequency for the power grid.
Figure BDA0002916072020000051
Figure BDA0002916072020000052
Wherein:
Figure BDA0002916072020000061
and S103, obtaining an influence factor index of the SVG additional impedance on the oscillation mode of the doubly-fed grid-connected system according to the single-input single-output equivalent complex circuit model.
In an embodiment of the invention, the step can specifically obtain an influence factor index of the SVG additional impedance on the oscillation mode of the doubly-fed grid-connected system by using a complex circuit mode power analysis method aiming at the single-input single-output equivalent complex circuit model.
In one embodiment of the invention, the influence factor index of SVG additional impedance on the oscillation mode of the doubly-fed grid-connected system is musTo indicate.
In one embodiment of the invention, the following formula is specifically adopted for evaluating the influence of SVG on the stability and oscillation mode of the doubly-fed grid-connected system:
Figure BDA0002916072020000062
wherein k isoIs a modal power coefficient, and the expression can be
Figure BDA0002916072020000063
okIs a modal power factor, which may be expressed as
Figure BDA0002916072020000064
YP_k，YD_kRespectively representing the primary and dual admittance of a doubly-fed plant and an AC network, i.e. YP_k＝YPR_v+YPG_v+YP_net，YD_k＝YDR_v+YDG_v+YD_net；Y* P_k，Y* D_kRespectively representing the conjugation of the dual-feed equipment and the dual admittance of the alternating current power grid; y isPD_v,Y* PD_vRespectively representing the transadmittance and conjugate components of the doubly-fed plant between node P and node D, where YPD_v＝YPRD_v+YPGD_v；
Figure BDA0002916072020000065
Respectively the conjugation of equivalent primary-dual complex circuits of the double-fed interactive system and the SVG interactive system at the voltage of a node P and a node D; y is an admittance matrix of an equivalent primary-dual complex circuit of the double-fed and SVG interactive system, and the expression can be as follows:
Figure BDA0002916072020000066
wherein:
Figure BDA0002916072020000071
u is a voltage vector satisfying YU ═ 0, that is, a right eigenvector of the matrix Y.
In a specific embodiment of the invention, the influence factor index is calculated according to the generalized admittance of the double-fed device and the alternating current power grid in the double-fed grid-connected system and the additional admittance introduced after the double-fed grid-connected system is added into the SVG.
And step S104, determining the influence of the SVG on the double-fed grid-connected system according to the influence factor index.
In an embodiment of the present invention, in the step S104, the influence of the SVG on the doubly-fed grid-connected system is determined according to the influence factor index, specifically, the influence of the SVG on the stability and the oscillation frequency of the doubly-fed grid-connected system is determined according to the influence factor index.
Fig. 2 is a flowchart of determining an influence of SVG on stability of a doubly-fed grid-connected system according to an embodiment of the present invention, and as shown in fig. 2, in an alternative embodiment of the present invention, the flowchart of determining an influence of SVG on stability of a doubly-fed grid-connected system includes step S201 and step S202.
And step S201, if the real part of the influence factor index is positive, determining to add SVG to reduce the stability of the doubly-fed grid-connected system.
And S202, if the real part of the influence factor index is negative, determining to add SVG to improve the stability of the double-fed grid-connected system.
Fig. 3 is a flowchart of determining an influence of SVG on an oscillation frequency of a doubly-fed grid-connected system according to an embodiment of the present invention, and as shown in fig. 3, in an alternative embodiment of the present invention, the flowchart of determining an influence of SVG on an oscillation frequency of a doubly-fed grid-connected system includes step S301 and step S302.
And S301, if the imaginary part of the influence factor index is positive, determining to add SVG to improve the oscillation frequency of the doubly-fed grid-connected system.
And step S302, if the imaginary part of the influence factor index is negative, determining to add SVG to reduce the oscillation frequency of the doubly-fed grid-connected system.
In the embodiment of the present invention, μs(s1) Can be reflected in the oscillation mode s1And defining the influence of the SVG on the oscillation mode of the original system as an influence factor index. Wherein Re (mu)s)，I.e. the impact factor index musThe real part of (d), represents the influence of SVG on system stability if Re (μ)s) The SVG provides a damping effect for the system for negative representation, the stability of the system is improved after the SVG is added, otherwise, the stability of the system small interference is deteriorated; im (mu)s) I.e. the impact factor index musRepresents the influence of SVG on the system oscillation frequency if Im(s)1) Is positive and Im (mu)s) To positive indicate that the oscillation frequency increases after the addition of SVG, whereas Im (mu)s) The negative system oscillation frequency decreases.
Therefore, the stability problem of the SVG accessing to the double-fed grid-connected system can be converted into the stability problem of a single-input single-output (SISO) equivalent circuit, and elements such as a phase shifter and the like which are difficult to analyze do not exist in the SISO equivalent complex circuit of the system. The method has clear physical mechanism and accurate depiction of the stability of the system small interference, and can be applied to analyzing the influence of the SVG on the oscillation mode of the double-fed equipment and the influence of the control structure and parameters of the SVG on the stability of the system.
The invention is described in further detail below with reference to the figures and the specific examples.
According to the established equivalent primary-dual complex circuit of the double-fed interactive system and the SVG interactive system, the invention selects the generalized admittance of the double-fed equipment and the alternating current power grid and the additional admittance introduced after the double-fed grid-connected system is added into the SVG to calculate the influence factor index musAccording to the influence factor index musAnd evaluating the influence of the SVG on the stability and the oscillation frequency of the doubly-fed grid-connected system.
The specific embodiment of the invention is as follows:
the structure of the converter and SVG interactive system shown in FIG. 6 is adopted, wherein the converter adopts a control mode of a constant direct current voltage outer ring, and a frequency domain and time domain model of the system is built in Matlab/Simulink to verify theoretical analysis. Because the double-fed equipment grid-connected system may have two kinds of oscillation problems of the middle frequency band and the low frequency band, simulation needs to be performed respectively, two groups of parameters shown in table 1 are used for discussion and analysis respectively, and system and equipment control parameters are shown in tables 1 and 2. In FIG. 6, Lf、CfAnd LgRespectively a filter inductor, a filter capacitor and a line powerFeeling of cold, LmFor mutual inductance of the motor, CdcIs a DC capacitor, LTIs a transformer inductor, UdcMeasuring the voltage for the inverter;
TABLE 1 converter grid-connected System parameters
Figure BDA0002916072020000081
Figure BDA0002916072020000091
TABLE 2 grid-connected SVG control parameters
Figure BDA0002916072020000092
Establishing a system impedance model under the working condition, wherein the current flowing into the double-fed equipment is taken as positive, and a dynamic model of the grid-side converter of the double-fed equipment is as follows:
Figure BDA0002916072020000093
wherein:
Figure BDA0002916072020000094
in the formula, subscript 0 denotes the steady state value of each variable, G3(s)＝Kdcp+KdciThe/s is a transfer function of a PI controller of a direct-current voltage outer ring; g4(s)＝Kcp+KciAnd/s is the transfer function of the PI controller of the current inner loop.
The dynamic model of the rotor side converter of the doubly-fed equipment set is as follows:
Figure BDA0002916072020000101
wherein:
Figure BDA0002916072020000102
in the formula (I), the compound is shown in the specification,
Figure BDA0002916072020000103
U0outputting the amplitude of the steady-state voltage for the motor; i iss0The amplitude of the steady-state current of the motor stator is obtained; i isr0The amplitude of the steady-state current of the motor rotor is obtained;
Figure BDA0002916072020000104
is a motor stator current steady state phase; g1(s)＝Ksp+KsiThe/s is the transfer function of the PI controller of the power outer loop; g2(s)＝Krp+KriThe/s is a transfer function of a PI controller of a rotor side current inner ring; l ismThe motor mutual inductance is adopted; l isr＝Lσr+LmA rotor side inductor; l iss＝Lσs+LmA stator side inductor;
the polar coordinate impedance model of the SVG is as follows:
Figure BDA0002916072020000105
for the control mode of the alternating voltage outer ring, the impedance expression is as follows:
Figure BDA0002916072020000106
for the reactive outer loop control mode, the impedance expression is as follows:
Figure BDA0002916072020000111
wherein: l isfFor the filter inductance, ω is the phase-locked loop output angular frequency, θpllFor outputting electrical angle, H, of phase-locked loopi(s) is the inner loop transfer function, Gac(s)、Gq(s) is the outer loop transfer function, Hpll(s) is a phase-locked loop transfer function, and the expression is as follows:
Figure BDA0002916072020000112
in the formula:
Figure BDA0002916072020000113
for each of the transfer function scaling parameters,
Figure BDA0002916072020000114
the parameters are integrated for each transfer function.
Regarding the converter and the equipment and the power grid outside the ports of the SVG as a network system, and obtaining a system dynamic equation as follows:
Figure BDA0002916072020000115
in the formula (I), the compound is shown in the specification,
Figure BDA0002916072020000116
is a filter capacitance matrix, B is a system node admittance matrix after node compression, LgIs the sum of the filter inductance and the line inductance of the LC filter, L1T，L2TIs an inductance of a transformer and is provided with a plurality of inductors,
Figure BDA0002916072020000117
Figure BDA0002916072020000118
representing the Kronecker product. Wherein:
Figure BDA0002916072020000119
the modal power can represent the participation degree of each generalized admittance in the complex circuit to the oscillation mode, so that the modal power can be expressed according to the modal workThe magnitude of the rate can be given a generalized admittance that causes the system to oscillate. After the SVG is added into the grid-connected system of the double-fed equipment set, the additional admittance introduced into the complex circuit is delta YP_sys,ΔYD_sys,ΔYPD_vAs shown in fig. 5, it is explained that SVG influences system modal power by adjusting network generalized impedance and current transformer generalized impedance at this time, thereby affecting system stability. In this oscillation mode, the additional admittance of the SVG is in parallel with the generalized admittance of the system, marked with a dashed line. Therefore, the influence of the SVG on the system stability can be evaluated according to the analytic expression of the SVG additional impedance on the system oscillation mode.
After the SVG is introduced, the change of the stability of the grid-connected system of the doubly-fed equipment is shown in table 3. For the oscillation mode 1 of the medium-frequency double-fed equipment, the stability of the system is slightly reduced after the SVG is added. And for the oscillation mode 2 of the low frequency band, the stability of the system is improved after the SVG is added.
Table 3 influence of adding SVG to different oscillation modes of the doubly-fed device
Figure BDA0002916072020000121
Therefore, the method can be applied to analyzing and evaluating the influence of the SVG on the oscillation mode of the double-fed grid-connected equipment, and the risk of oscillation of the double-fed grid-connected system caused by the introduction of the SVG is reduced.
It should be noted that the steps illustrated in the flowcharts of the figures may be performed in a computer system such as a set of computer-executable instructions and that, although a logical order is illustrated in the flowcharts, in some cases, the steps illustrated or described may be performed in an order different than presented herein.
Based on the same inventive concept, the embodiment of the present invention further provides a device for analyzing the influence of the SVG on the doubly-fed grid-connected system, which can be used to implement the method for analyzing the influence of the SVG on the doubly-fed grid-connected system described in the above embodiment, as described in the following embodiment. Because the principle of analyzing the device solution problem of the influence of the SVG on the doubly-fed grid-connected system is similar to the method of analyzing the influence of the SVG on the doubly-fed grid-connected system, the embodiment of the device for analyzing the influence of the SVG on the doubly-fed grid-connected system can refer to the embodiment of the method for analyzing the influence of the SVG on the doubly-fed grid-connected system, and repeated parts are not repeated. As used hereinafter, the term "unit" or "module" may be a combination of software and/or hardware that implements a predetermined function. Although the means described in the embodiments below are preferably implemented in software, an implementation in hardware, or a combination of software and hardware is also possible and contemplated.
Fig. 4 is a block diagram of a device for analyzing an influence of SVG on a doubly-fed grid-connected system according to an embodiment of the present invention, and as shown in fig. 4, the device for analyzing an influence of SVG on a doubly-fed grid-connected system according to an embodiment of the present invention includes:
the equivalent model acquisition unit 1 is used for acquiring an equivalent model of interaction between the SVG and the doubly-fed grid-connected system;
the model transformation unit 2 is used for simplifying the equivalent model into a single-input single-output equivalent complex circuit model;
the influence factor index determining unit 3 is used for obtaining an influence factor index of the SVG additional impedance on the system oscillation mode according to the single-input single-output equivalent complex circuit model;
and the influence analysis unit 4 is used for determining the influence of the SVG on the double-fed grid-connected system according to the influence factor index.
In an embodiment of the present invention, the model transformation unit 2 may simplify the equivalent model into a single-input single-output equivalent complex circuit model through linear transformation.
In an embodiment of the present invention, the influence factor index determining unit 3 may obtain, by using a complex circuit modal power analysis method, an influence factor index of the SVG additional impedance on the system oscillation mode for the single-input single-output equivalent complex circuit model.
In an embodiment of the present invention, the influence analysis unit 4 is specifically configured to determine, according to the influence factor indicator, an influence of the SVG on the stability and the oscillation frequency of the doubly-fed grid-connected system.
In one embodiment of the present invention, the influence analysis unit 4 includes:
the first analysis module is used for determining that SVG is added to reduce the stability of the double-fed grid-connected system if the real part of the influence factor index is positive;
and the second analysis module is used for determining that the SVG is added to improve the stability of the double-fed grid-connected system if the real part of the influence factor index is negative.
In one embodiment of the present invention, the influence analysis unit 4 further includes:
the third analysis module is used for determining that the SVG is added to improve the oscillation frequency of the doubly-fed grid-connected system if the imaginary part of the influence factor index is positive;
and the fourth analysis module is used for determining that the SVG is added to reduce the oscillation frequency of the doubly-fed grid-connected system if the imaginary part of the influence factor index is negative.
To achieve the above object, according to another aspect of the present application, there is also provided a computer apparatus. As shown in fig. 7, the computer device comprises a memory, a processor, a communication interface and a communication bus, wherein a computer program that can be run on the processor is stored in the memory, and the steps of the method of the above embodiment are realized when the processor executes the computer program.
The processor may be a Central Processing Unit (CPU). The Processor may also be other general purpose processors, Digital Signal Processors (DSPs), Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs) or other Programmable logic devices, discrete Gate or transistor logic devices, discrete hardware components, or a combination thereof.
The memory, which is a non-transitory computer readable storage medium, may be used to store non-transitory software programs, non-transitory computer executable programs, and units, such as the corresponding program units in the above-described method embodiments of the present invention. The processor executes various functional applications of the processor and the processing of the work data by executing the non-transitory software programs, instructions and modules stored in the memory, that is, the method in the above method embodiment is realized.
The memory may include a storage program area and a storage data area, wherein the storage program area may store an operating system, an application program required for at least one function; the storage data area may store data created by the processor, and the like. Further, the memory may include high speed random access memory, and may also include non-transitory memory, such as at least one disk storage device, flash memory device, or other non-transitory solid state storage device. In some embodiments, the memory optionally includes memory located remotely from the processor, and such remote memory may be coupled to the processor 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.
The one or more units are stored in the memory and when executed by the processor perform the method of the above embodiments.
The specific details of the computer device may be understood by referring to the corresponding related descriptions and effects in the above embodiments, and are not described herein again.
In order to achieve the above object, according to another aspect of the present application, there is also provided a computer-readable storage medium storing a computer program which, when executed in a computer processor, implements the steps in the above method for analyzing the influence of SVG on a doubly-fed grid-connected system. It will be understood by those skilled in the art that all or part of the processes of the methods of the embodiments described above can be implemented by a computer program, which can be stored in a computer-readable storage medium, and when executed, can include the processes of the embodiments of the methods described above. The storage medium may be a magnetic Disk, an optical Disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a Flash Memory (Flash Memory), a Hard Disk (Hard Disk Drive, abbreviated as HDD) or a Solid State Drive (SSD), etc.; the storage medium may also comprise a combination of memories of the kind described above.
It will be apparent to those skilled in the art that the modules or steps of the present invention described above may be implemented by a general purpose computing device, they may be centralized on a single computing device or distributed across a network of multiple computing devices, and they may alternatively be implemented by program code executable by a computing device, such that they may be stored in a storage device and executed by a computing device, or fabricated separately as individual integrated circuit modules, or fabricated as a single integrated circuit module from multiple modules or steps. Thus, the present invention is not limited to any specific combination of hardware and software.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (12)

1. A method for analyzing the influence of SVG on a double-fed grid-connected system is characterized by comprising the following steps:
obtaining an equivalent model of interaction of the SVG and a double-fed grid-connected system;
simplifying the equivalent model into a single-input single-output equivalent complex circuit model;
obtaining an influence factor index of SVG additional impedance on an oscillation mode of the double-fed grid-connected system according to the single-input single-output equivalent complex circuit model;
and determining the influence of the SVG on the doubly-fed grid-connected system according to the influence factor index.
2. The method for analyzing influence of SVG on a doubly-fed grid-connected system according to claim 1, wherein said equivalent model is constructed by a method of analyzing generalized impedance and equivalent pro-dual complex circuit in small-disturbance stable analysis.
3. The method for analyzing the influence of SVG on the doubly fed grid connected system according to claim 1, wherein said determining the influence of SVG on the doubly fed grid connected system based on said influence factor metrics comprises:
and determining the influence of the SVG on the stability and the oscillation frequency of the doubly-fed grid-connected system according to the influence factor index.
4. The method for analyzing influence of SVG on a doubly-fed grid-connected system of claim 3, wherein said determining influence of SVG on stability and oscillation frequency of a doubly-fed grid-connected system according to said influence factor metrics comprises:
if the real part of the influence factor index is positive, determining to add SVG to reduce the stability of the double-fed grid-connected system;
and if the real part of the influence factor index is negative, determining to add the SVG so as to improve the stability of the double-fed grid-connected system.
5. The method for analyzing influence of SVG on a doubly-fed grid-connected system of claim 3, wherein said determining influence of SVG on stability and oscillation frequency of a doubly-fed grid-connected system according to said influence factor metrics comprises:
if the imaginary part of the influence factor index is positive, determining to add SVG to improve the oscillation frequency of the doubly-fed grid-connected system;
and if the imaginary part of the influence factor index is negative, determining to add the SVG to reduce the oscillation frequency of the doubly-fed grid-connected system.
6. The method for analyzing influence of SVG on a doubly-fed grid-connected system according to claim 1, wherein the resonance zero point of said single-input single-output equivalent complex circuit model is the characteristic root of said equivalent model.
7. The utility model provides a device of analysis SVG to double-fed grid-connected system's influence which characterized in that includes:
the equivalent model acquisition unit is used for acquiring an equivalent model of interaction of the SVG and the doubly-fed grid-connected system;
the model transformation unit is used for simplifying the equivalent model into a single-input single-output equivalent complex circuit model;
the influence factor index determining unit is used for obtaining the influence factor index of the SVG additional impedance on the system oscillation mode according to the single-input single-output equivalent complex circuit model;
and the influence analysis unit is used for determining the influence of the SVG on the double-fed grid-connected system according to the influence factor index.
8. The apparatus for analyzing influence of SVG on a doubly-fed grid-connected system according to claim 7, wherein said influence analyzing unit is specifically configured to determine influence of SVG on stability and oscillation frequency of the doubly-fed grid-connected system according to said influence factor indicator.
9. The apparatus for analyzing influence of SVG on a doubly-fed grid-connected system according to claim 8, wherein said influence analyzing unit includes:
the first analysis module is used for determining that SVG is added to reduce the stability of the double-fed grid-connected system if the real part of the influence factor index is positive;
and the second analysis module is used for determining that the SVG is added to improve the stability of the double-fed grid-connected system if the real part of the influence factor index is negative.
10. The apparatus for analyzing influence of SVG on a doubly-fed grid-connected system according to claim 8, wherein said influence analyzing unit includes:
the third analysis module is used for determining that the SVG is added to improve the oscillation frequency of the doubly-fed grid-connected system if the imaginary part of the influence factor index is positive;
and the fourth analysis module is used for determining that the SVG is added to reduce the oscillation frequency of the doubly-fed grid-connected system if the imaginary part of the influence factor index is negative.
11. A computer device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, characterized in that the processor implements the method of any of claims 1 to 6 when executing the computer program.
12. A computer-readable storage medium, in which a computer program is stored which, when executed in a computer processor, implements the method of any one of claims 1 to 6.
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