CN113285639B - Method and system for determining negative sequence impedance of base frequency of double-fed induction generator system - Google Patents

Method and system for determining negative sequence impedance of base frequency of double-fed induction generator system Download PDF

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CN113285639B
CN113285639B CN202110326268.4A CN202110326268A CN113285639B CN 113285639 B CN113285639 B CN 113285639B CN 202110326268 A CN202110326268 A CN 202110326268A CN 113285639 B CN113285639 B CN 113285639B
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phase
voltage
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rsc
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CN113285639A (en
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刘其辉
逄思敏
吴林林
刘辉
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State Grid Corp of China SGCC
North China Electric Power University
Electric Power Research Institute of State Grid Jibei Electric Power Co Ltd
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State Grid Corp of China SGCC
North China Electric Power University
Electric Power Research Institute of State Grid Jibei Electric Power Co Ltd
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P9/00—Arrangements for controlling electric generators for the purpose of obtaining a desired output
    • H02P9/14—Arrangements for controlling electric generators for the purpose of obtaining a desired output by variation of field
    • H02P9/16—Arrangements for controlling electric generators for the purpose of obtaining a desired output by variation of field due to variation of ohmic resistance in field circuit, using resistances switched in or out of circuit step by step
    • 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
    • H02J3/26—Arrangements for eliminating or reducing asymmetry in polyphase networks
    • 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
    • H02J3/381—Dispersed generators
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P9/00—Arrangements for controlling electric generators for the purpose of obtaining a desired output
    • H02P9/007—Control circuits for doubly fed generators
    • 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]
    • 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
    • H02J2300/00—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
    • H02J2300/20—The dispersed energy generation being of renewable origin
    • H02J2300/28—The renewable source being wind energy
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P2101/00—Special adaptation of control arrangements for generators
    • H02P2101/15—Special adaptation of control arrangements for generators for wind-driven turbines
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
    • Y02E40/50—Arrangements for eliminating or reducing asymmetry in polyphase networks

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Control Of Eletrric Generators (AREA)

Abstract

The invention relates to a method and a system for determining fundamental frequency negative sequence impedance of a doubly-fed induction generator system. The method comprises the following steps: the relation among GSC output current, voltage and grid-connected point voltage under an abc static coordinate system, and the relation among RSC current, voltage and flux linkage of a generator set rotor side converter; converting three-phase voltage at a fan grid-connected point, current at a GSC (global system control) alternating current side and current in RSC (received signal code) into a frequency domain; determining a GSC coordinate transformation matrix and an RSC coordinate transformation matrix, determining a dq component of a voltage command value output by the GSC and determining a dq component of a voltage command value output by the RSC; determining a phase a output voltage command value of GSC and RSC in an abc coordinate system; determining a GSC direct current steady-state characteristic quantity and an RSC direct current steady-state characteristic quantity, and determining a GSC fundamental frequency negative sequence impedance model and an RSC fundamental frequency negative sequence impedance model; and determining a negative sequence impedance model of the doubly-fed induction generator system according to the two models. The method can accurately determine the fundamental frequency negative sequence impedance of the doubly-fed induction generator system.

Description

Method and system for determining fundamental frequency negative sequence impedance of doubly-fed induction generator system
Technical Field
The invention relates to the technical field of wind power generation, in particular to a method and a system for determining fundamental frequency negative sequence impedance of a double-fed induction generator system.
Background
The large-scale wind power centralized access power grid is influenced by the time-varying characteristic of the negative sequence impedance of a new energy unit, the phenomenon of three-phase unbalanced voltage is easy to occur, the existing main factors causing the unbalanced voltage are concentrated on the asymmetry of external equipment such as a circuit, a transformer, a load and the like, relevant mechanisms are researched from the perspective of the self negative sequence impedance of a double-fed induction generator system (a double-fed fan), and the fundamental frequency negative sequence impedance model of the existing double-fed induction generator system cannot intuitively reflect the parameters of the fan and the influence of links such as a phase-locked loop, a current regulator and the like on the fundamental frequency negative sequence impedance.
Therefore, it is necessary to establish a detailed and accurate fundamental frequency negative sequence impedance of the doubly-fed induction generator system so as to analyze the mechanism of the voltage imbalance through the time-varying characteristic of the negative sequence impedance of the wind turbine.
Disclosure of Invention
The invention aims to provide a method and a system for determining the fundamental frequency negative sequence impedance of a doubly-fed induction generator system, which can accurately determine the fundamental frequency negative sequence impedance of the doubly-fed induction generator system and enlarge the application range of the fundamental frequency negative sequence impedance of a doubly-fed fan.
In order to achieve the purpose, the invention provides the following scheme:
a method for determining the fundamental frequency negative sequence impedance of a doubly-fed induction generator system comprises the following steps:
acquiring three-phase current and three-phase voltage at the GSC alternating current side of a grid-side converter in a doubly-fed induction generator system under an abc static coordinate system, GSC output filter inductance, three-phase voltage at a fan grid-connected point, three-phase current flowing into a stator winding, three-phase current flowing into a rotor winding, three-phase voltage of the stator winding, three-phase voltage of a rotor winding, a generator stator and rotor turn ratio, resistance converted into a stator winding of a stator-side generator and resistance of the rotor winding, a self-inductance matrix and a mutual inductance matrix converted into a stator-side generator stator and rotor;
determining the relation between the GSC output current and voltage and the grid-connected point voltage under an abc static coordinate system according to the three-phase current and the three-phase voltage of the GSC AC side of the grid-side converter, the GSC output filter inductance and the three-phase voltage of the fan grid-connected point;
determining the relation of RSC current, voltage and flux linkage of a unit rotor side converter under an abc static coordinate system according to three-phase current flowing into a stator winding, three-phase current flowing into a rotor winding, three-phase voltage of the stator winding, three-phase voltage of the rotor winding, the generator stator, the rotor turn ratio, resistance of the generator stator winding and the rotor winding converted to the stator side, a self-inductance matrix and a mutual inductance matrix of the generator stator and the generator rotor converted to the stator side and the rotor side;
converting the three-phase voltage at the grid-connected point of the fan, the three-phase current at the GSC alternating current side, the three-phase current flowing into the stator winding and the three-phase current flowing into the rotor winding from time domain to frequency domain;
according to a phase locking angle in a phase locking loop in a double-fed induction generator system, determining a GSC coordinate transformation matrix and an RSC coordinate transformation matrix by adopting a harmonic linearization method;
converting the three-phase current on the GSC alternating current side after the frequency domain is converted into a dq coordinate system according to the GSC coordinate conversion matrix, and further determining the dq component of the voltage command value output by the GSC;
converting the three-phase current flowing into the stator winding after the frequency domain conversion and the three-phase current flowing into the rotor winding after the frequency domain conversion into a dq coordinate system according to the RSC coordinate transformation matrix, and further determining the dq component of the voltage command value output by the RSC;
determining an a-phase output voltage command value of the GSC under an abc coordinate system according to an inverse matrix of a GSC coordinate transformation matrix and a dq component of a voltage command value output by the GSC;
determining an a-phase output voltage command value of the RSC in an abc coordinate system according to an inverse matrix of the RSC coordinate transformation matrix and a dq component of a voltage command value output by the RSC;
determining a GSC direct-current steady-state characteristic quantity according to the relation between GSC output current, voltage and grid-connected point voltage under an abc static coordinate system, three-phase voltage at a fan grid-connected point after frequency domain conversion and an a-phase output voltage instruction value of the GSC under the abc coordinate system, and further determining a base frequency negative sequence impedance model of the GSC;
determining RSC direct-current steady-state characteristic quantity according to the relation between RSC current, voltage and flux linkage of the unit rotor side converter in the abc static coordinate system, three-phase current flowing into a stator winding after frequency domain conversion, three-phase current flowing into a rotor winding after frequency domain conversion and an a-phase output voltage command value of the RSC in the abc coordinate system, and further determining a fundamental frequency negative sequence impedance model of the controlled DFIG system;
determining a negative-sequence impedance model of a doubly-fed induction generator system according to the fundamental frequency negative-sequence impedance model of the GSC and the fundamental frequency negative-sequence impedance model of the controlled DFIG;
and determining the fundamental frequency negative sequence impedance of the doubly-fed induction generator system according to the negative sequence impedance model of the doubly-fed induction generator system.
Optionally, the determining, according to the three-phase current, the three-phase voltage, the GSC output filter inductance at the ac side of the grid-side converter GSC and the three-phase voltage at the grid-connected point of the fan, a relationship between the GSC output current, the voltage and the grid-connected point voltage in the abc static coordinate system specifically includes:
using formulas
Figure BDA0002994776060000031
Determining the relation between GSC output current, voltage and grid-connected point voltage under an abc static coordinate system;
using formulas
Figure BDA0002994776060000032
Converting positive, negative and zero sequence components;
wherein L is GSC output filter inductance iga、igbAnd igcThree-phase current, v, for the alternating side of GSCa、vbAnd vcFor three-phase voltage, v, at the point of fan grid connectionia、vibAnd vicThree phase voltage i on the AC side of GSCg1、ig2、ig0Is the positive, negative and zero sequence components of the GSC alternating side current vi1、vi2、vi0Is the positive, negative and zero sequence components of the GSC AC side voltage, v1、v2、v0The positive, negative and zero sequence components of the voltage of the fan grid-connected point.
Optionally, the determining, according to the three-phase current flowing into the stator winding, the three-phase current flowing into the rotor winding, the three-phase voltage of the stator winding, the three-phase voltage of the rotor winding, the generator stator, the rotor turn ratio, the resistance of the generator stator winding and the resistance of the rotor winding translated to the stator side, the self-inductance matrix and the mutual-inductance matrix of the generator stator and the rotor translated to the stator side, a relationship between the RSC current, the voltage and the flux linkage of the unit rotor side converter in the abc stationary coordinate system specifically includes:
using formulas
Figure BDA0002994776060000041
Determining the relationship among RSC current, voltage and flux linkage of a generator set rotor side converter in an abc static coordinate system;
using formulas
Figure BDA0002994776060000042
Carrying out conversion of positive, negative and zero sequence components;
wherein v iss_abcFor three-phase voltage flowing into the stator winding, is_abcFor three-phase current flowing in the stator winding, vr_abcBeing three-phase voltages of rotor windings, ir_abcFor three-phase current flowing in the rotor winding, KeFor the number ratio of stator and rotor turns of the generator,. psis_abcAnd psir_abcIs a magnetic linkage in the abc coordinate system, Lss、Lsr、LrsAnd LrrFor converting self-inductance matrix and mutual inductance matrix, R, of stator and rotor of generator to stator sides、RrFor conversion into the resistance of the stator and rotor windings of the generator on the stator side, vs_pnVoltage, v, expressed for positive and negative sequence of the statorr_pnVoltages represented by positive and negative sequences of rotors, is_pnCurrent represented by positive and negative sequence of stator, ir_pnCurrent, psi, expressed for positive and negative order of the rotors_pnFlux linkage, psi, expressed for positive and negative order of the statorr_pnAnd the positive and negative sequences of the rotor represent the magnetic chain.
Optionally, the determining, according to a phase-locked angle in a phase-locked loop in the doubly-fed induction generator system, the GSC coordinate transformation matrix and the RSC coordinate transformation matrix by using a harmonic linearization method specifically includes:
using a formula
Figure BDA0002994776060000043
Determining a GSC coordinate transformation matrix;
using formulas
Figure RE-GDA0003115302050000051
Determining an RSC coordinate transformation matrix;
wherein, thetaPLLTo lock the phase angle, thetarIs the rotor position angle.
Optionally, the determining a steady-state characteristic quantity of the GSC direct current according to a relationship between the GSC output current and the voltage of the grid-connected point in the abc static coordinate system, the three-phase voltage at the wind turbine grid-connected point after the frequency domain conversion, and an a-phase output voltage command value of the GSC in the abc static coordinate system, so as to determine the fundamental frequency negative sequence impedance model of the GSC specifically includes:
using formulas
Figure BDA0002994776060000052
Determining a GSC direct current steady-state characteristic quantity;
using formulas
Figure BDA0002994776060000053
Determining a fundamental frequency negative sequence impedance model of the GSC;
wherein，D0And Q0For the steady-state characterization of GSC direct current, V1Is the positive sequence amplitude, K, of the fundamental wave of the network voltagedq＝ω1L is GSC current loop coupling coefficient, L is GSC output filter inductance,
Figure BDA0002994776060000054
is the fundamental positive sequence component of the grid current,
Figure BDA0002994776060000055
is the initial phase of the fundamental wave of the current, f1Is the fundamental frequency, j is the complex imaginary component, Hgi(2jω1) Is the transfer function of the network-side converter PI regulator at fundamental frequency, F (2j omega)1) As a transfer function of the phase-locked loop PI regulator at fundamental frequency, omega1At fundamental angular velocity, I1 *＝(Idref－jIqref) And/2 is the conjugate of the positive sequence fundamental current.
Optionally, the determining a RSC direct-current steady-state characteristic quantity according to a relationship between a current, a voltage and a flux of the unit rotor-side converter RSC in the abc static coordinate system, a three-phase current flowing into the stator winding after the frequency domain is converted, a three-phase current flowing into the rotor winding after the frequency domain is converted, and an a-phase output voltage command value of the RSC in the abc coordinate system further determines a fundamental frequency negative sequence impedance model of the RSC specifically includes:
using formulas
Figure BDA0002994776060000056
Determining RSC direct current steady-state characterization quantity;
using formulas
Figure BDA0002994776060000061
Determining a fundamental frequency negative sequence impedance model of RSC;
wherein D isr0And Qr0Is a steady-state characterization quantity of RSC direct current, omegasIs the electrical angular velocity of the stator, Ird、IrqD, q-axis components of the rotor current, Krdq＝ωs(Lr－Lm 2/Ls) Is the RSC current loop decoupling coefficient, LmIs the mutual inductance value between stator and rotor windings, Ird、IrqD and q-axis components of the rotor current, Ir1The amplitude of the fundamental frequency positive sequence component of the current at the rotor end of the generator,
Figure BDA0002994776060000062
as an inductance of the rotor, there is a high inductance,
Figure BDA0002994776060000063
is stator inductance, Vsd，VsqIs the d, q axis component of the stator voltage, s ═ j ω1，F(2jω1) Being the transfer function of a phase-locked loop PI regulator at fundamental frequency, Hri(2jω1) For the transfer function of the rotor side converter PI regulator at fundamental frequency,
Figure BDA0002994776060000064
is the slip.
Optionally, the determining a negative-sequence impedance model of the doubly-fed induction generator system according to the fundamental frequency negative-sequence impedance model of the GSC and the fundamental frequency negative-sequence impedance model of the controlled DFIG specifically includes:
using formulas
Figure BDA0002994776060000065
Determining a negative sequence impedance model of the doubly-fed induction generator system;
wherein the content of the first and second substances,
Figure BDA0002994776060000066
is a negative sequence impedance model of a double-fed induction generator system,
Figure BDA0002994776060000067
being a fundamental negative-order impedance model of the GSC,
Figure BDA0002994776060000068
is a fundamental negative sequence impedance model of RSC.
A double-fed induction generator system fundamental frequency negative sequence impedance determination system, comprising:
the parameter acquisition module is used for acquiring three-phase current and three-phase voltage of the alternating current side of a converter grid-side converter GSC in the doubly-fed induction generator system under an abc static coordinate system, GSC output filter inductance, three-phase voltage at a fan grid-connected point, three-phase current flowing into a stator winding, three-phase current flowing into a rotor winding, three-phase voltage of the stator winding, three-phase voltage of the rotor winding, a generator stator and a rotor turn ratio, resistance of a generator stator winding and resistance of a rotor winding translated to the stator side, a self-inductance matrix and a mutual inductance matrix of the generator stator and the rotor translated to the stator side;
the system comprises a relation determining module of GSC output current, voltage and grid-connected point voltage under an abc static coordinate system, wherein the relation determining module is used for determining the relation of the GSC output current, the voltage and the grid-connected point voltage under the abc static coordinate system according to three-phase current and three-phase voltage at the alternating current side of a grid-side converter GSC, GSC output filter inductance and three-phase voltage at a fan grid-connected point;
the relation determination module of the RSC current, voltage and flux linkage of the unit rotor side converter under the abc static coordinate system is used for determining the relation of the RSC current, voltage and flux linkage of the unit rotor side converter under the abc static coordinate system according to the three-phase current flowing into the stator winding, the three-phase current flowing into the rotor winding, the three-phase voltage of the stator winding, the three-phase voltage of the rotor winding, the turn ratio of the generator stator and the rotor, the resistance of the generator stator winding and the resistance of the rotor winding translated to the stator side, the self-inductance matrix of the generator stator and the rotor translated to the stator side and the mutual inductance matrix;
the frequency domain conversion module is used for converting the three-phase voltage at the grid-connected point of the fan, the three-phase current at the GSC alternating current side, the three-phase current flowing into the stator winding and the three-phase current flowing into the rotor winding from time domain to frequency domain;
the coordinate transformation matrix determining module is used for determining a GSC coordinate transformation matrix and an RSC coordinate transformation matrix by adopting a harmonic linearization method according to a phase locking angle in a phase locking loop in the double-fed induction generator system;
the voltage instruction value determining module is used for converting the three-phase current on the alternating current side of the GSC after the frequency domain conversion into a dq coordinate system according to the GSC coordinate conversion matrix so as to determine the dq component of the voltage instruction value output by the GSC;
the RSC output voltage command value determining module is used for converting the three-phase current flowing into the stator winding after the frequency domain conversion and the three-phase current flowing into the rotor winding after the frequency domain conversion into a dq coordinate system according to the RSC coordinate transformation matrix so as to determine the dq component of the RSC output voltage command value;
the device comprises an a-phase output voltage instruction value determining module of the GSC under an abc coordinate system, a voltage instruction value determining module and a control module, wherein the a-phase output voltage instruction value determining module is used for determining an a-phase output voltage instruction value of the GSC under the abc coordinate system according to an inverse matrix of a GSC coordinate transformation matrix and a dq component of a voltage instruction value output by the GSC;
the RSC output voltage command value determining module is used for determining an a-phase output voltage command value of the RSC in the abc coordinate system according to an inverse matrix of the RSC coordinate transformation matrix and a dq component of the voltage command value output by the RSC;
the GSC fundamental frequency negative sequence impedance model determining module is used for determining GSC direct current steady-state characteristic quantity according to the relation between GSC output current, voltage and grid-connected point voltage under an abc static coordinate system, three-phase voltage at a fan grid-connected point after frequency domain conversion and a-phase output voltage instruction value of the GSC under the abc coordinate system, and further determining a GSC fundamental frequency negative sequence impedance model;
the RSC fundamental frequency negative sequence impedance model determining module is used for determining RSC direct current steady-state characteristic quantity according to the relation between RSC current, voltage and flux of the unit rotor side converter in the abc static coordinate system, three-phase current flowing into the stator winding after frequency domain conversion, three-phase current flowing into the rotor winding after frequency domain conversion and an a-phase output voltage instruction value of the RSC in the abc coordinate system, and further determining a fundamental frequency negative sequence impedance model of the controlled DFIG;
the double-fed induction generator system negative sequence impedance model determining module is used for determining a double-fed induction generator system negative sequence impedance model according to the GSC fundamental frequency negative sequence impedance model and the controlled DFIG fundamental frequency negative sequence impedance model;
and the double-fed induction generator system fundamental frequency negative sequence impedance determining module is used for determining the double-fed induction generator system fundamental frequency negative sequence impedance according to the double-fed induction generator system negative sequence impedance model.
According to the specific embodiment provided by the invention, the invention discloses the following technical effects:
according to the method and the system for determining the fundamental frequency negative sequence impedance of the doubly-fed induction generator system, provided by the invention, the calculated value is more accurate by determining the negative sequence impedance model of the doubly-fed induction generator system through the fundamental frequency negative sequence impedance model of the GSC and the fundamental frequency negative sequence impedance model of the controlled DFIG. And moreover, according to a phase-locked angle in a phase-locked loop in the double-fed induction generator system, a GSC coordinate transformation matrix and an RSC coordinate transformation matrix are determined by adopting a harmonic linearization method, and disturbance of fundamental frequency negative sequence impedance on an output phase angle of the phase-locked loop is considered, so that the model is more accurate and the precision is higher. Furthermore, the GSC direct-current steady-state characteristic quantity and the RSC direct-current steady-state characteristic quantity are determined to reflect the states of the fan running at different working points, so that a fan fundamental frequency negative sequence impedance model under different working conditions can be established. The invention can intuitively reflect each control link of the fan and the influence of voltage and current on negative sequence impedance of the fan. The modeling method improves the modeling precision of the fundamental frequency negative sequence impedance of the doubly-fed fan, can accurately determine the fundamental frequency negative sequence impedance of the doubly-fed induction generator system, and enlarges the application range of the fundamental frequency negative sequence impedance of the doubly-fed fan.
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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 required to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without inventive labor.
Fig. 1 is a schematic flow chart of a method for determining the fundamental frequency negative sequence impedance of a doubly-fed induction generator system according to the present invention;
FIG. 2 is a block diagram of a doubly-fed induction generator control;
FIG. 3 is a block diagram of a phase locked loop;
FIG. 4 is a GSC current regulator control block diagram;
FIG. 5 is a RSC current regulator control block diagram;
fig. 6 is a schematic diagram of a negative sequence impedance model of a doubly-fed induction generator system.
Detailed Description
The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying 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.
The invention aims to provide a method and a system for determining the fundamental frequency negative sequence impedance of a doubly-fed induction generator system, which can accurately determine the fundamental frequency negative sequence impedance of the doubly-fed induction generator system and enlarge the application range of the fundamental frequency negative sequence impedance of a doubly-fed fan.
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.
Fig. 1 is a schematic flow chart of a method for determining a negative sequence impedance of a fundamental frequency of a doubly-fed induction generator system, as shown in fig. 1, the method for determining the negative sequence impedance of the fundamental frequency of the doubly-fed induction generator system provided by the present invention comprises:
s101, three-phase current, three-phase voltage, GSC output filter inductance, three-phase voltage at a fan grid-connected point, three-phase current flowing into a stator winding, three-phase current flowing into a rotor winding, three-phase voltage of the stator winding, three-phase voltage of the rotor winding, a turn ratio of a generator stator and a rotor, resistance of a generator stator winding and a rotor winding converted to the stator side, a self-inductance matrix and a mutual inductance matrix of the generator stator and the rotor converted to the stator side are obtained from a grid-side converter GSC alternating current side of a double-fed induction generator system in an abc static coordinate system.
And S102, determining the relation between the GSC output current and voltage and the grid-connected point voltage under an abc static coordinate system according to the three-phase current and the three-phase voltage of the grid-side converter GSC alternating current side, the GSC output filter inductance and the three-phase voltage of the fan grid-connected point.
As shown in fig. 2, S102 specifically includes:
using formulas
Figure BDA0002994776060000101
And determining the relation between the GSC output current, the voltage and the grid-connected point voltage under the abc static coordinate system.
Using a formula
Figure BDA0002994776060000102
And converting the positive, negative and zero sequence components. In order to meet the modeling background, the asymmetry phenomenon of the voltage and the current of the fan system is analyzed.
Wherein L is GSC output filter inductance iga、igbAnd igcThree-phase current, v, on the alternating side of GSCa、vbAnd vcFor three-phase voltage, v, at the point of fan integrationia、vibAnd vicThree-phase voltage i on the AC side of GSCg1、ig2、ig0Is the positive, negative and zero sequence components of the GSC alternating current side current, vi1、vi2、vi0Is the positive, negative and zero sequence components of the GSC AC side voltage, v1、v2、v0Positive, negative and zero sequence components of the voltage of the fan grid connection point.
As shown in fig. 2, θrIs the rotor position angle, ωrIs the electrical angular velocity, theta, of the rotorPLLFor locking the phase angle, VdcIs DC voltage, L is GSC output filter inductance, ZgridTo remove the impedance of the grid system and the transmission line, vabcFor three-phase voltage, i, at fan grid-connected point PCC1r_abcFor the current flowing in the rotor winding, is_abcIs the current flowing into the stator winding; i.e. ig_abcIs the current on the alternating current side of the GSC; i.e. irdq_ref、igdq_ref、irdq、igdq、 vrdq_ref、vgdq_refReference values, input current values and output voltage values of the RSC current regulator and the GSC current regulator respectively; pref、QrefP, Q are reference and input power values, respectively, for the power control outer loop of the RSC; vdc_refThe reference value of the outer loop is controlled for the voltage of the GSC.
S103, determining the relation of RSC current, voltage and flux linkage of a unit rotor side converter under an abc static coordinate system according to the three-phase current flowing into a stator winding, the three-phase current flowing into a rotor winding, the three-phase voltage of the stator winding, the three-phase voltage of a rotor winding, the three-phase voltage of the generator stator winding, the resistance of a generator stator winding, the resistance of the rotor winding, the resistance of a generator stator winding, the self-inductance matrix and the mutual inductance matrix, wherein the resistance is converted to the stator side;
s103 specifically comprises the following steps:
using formulas
Figure BDA0002994776060000111
Determining the relationship among RSC current, voltage and flux linkage of a generator set rotor side converter under an abc static coordinate system;
using formulas
Figure BDA0002994776060000112
Carrying out conversion of positive, negative and zero sequence components;
wherein v iss_abcFor three-phase voltage flowing into the stator winding, is_abcFor three-phase current flowing in the stator winding, vr_abcFor three-phase voltage flowing into rotor windings, ir_abcFor three-phase current flowing into the rotor winding, KeFor the number ratio of stator and rotor turns of the generator, psis_abcAnd psir_abcIs a magnetic linkage in abc coordinate system, Lss、Lsr、LrsAnd LrrFor converting self-inductance matrix and mutual inductance matrix, R, of stator and rotor of generator to stator sides、RrFor conversion into the resistance of the stator and rotor windings of the generator on the stator side, vs_pnPositive and negative sequence components of the stator voltage, vr_pnPositive and negative sequence components of rotor voltage, is_pnPositive and negative sequence components of stator current, ir_pnIs the positive and negative sequence component of the rotor current, psis_pnIs the positive and negative sequence component of the stator flux linkage, #r_pnThe positive and negative sequence components of the rotor flux linkage.
Wherein the content of the first and second substances,
Figure BDA0002994776060000121
Figure BDA0002994776060000122
Lls、Llrthe leakage inductance values of the stator and the rotor are obtained; l isms、LmIs the mutual inductance value corresponding to the maximum mutual inductance flux of the single-phase winding cross link of the stator and the rotor windings, and is converted into Lms＝Lmr＝2Lm/3 wherein LmIs the mutual inductance value between stator and rotor windings.
And S104, performing time domain to frequency domain conversion on the three-phase voltage at the fan grid-connected point PCC1, the three-phase current at the GSC alternating current side, the three-phase current flowing into the stator winding and the three-phase current flowing into the rotor winding.
The voltage frequency domain expression of the PCC1 point under the abc coordinate system is as follows:
Figure BDA0002994776060000123
Figure BDA0002994776060000124
Figure BDA0002994776060000125
in the formula (I), the compound is shown in the specification,
Figure BDA0002994776060000126
is the initial phase of the voltage fundamental wave;
Figure BDA0002994776060000127
the frequency domain expression of the GSC output current under the abc coordinate system is as follows:
Figure BDA0002994776060000128
Figure BDA0002994776060000131
Figure BDA0002994776060000132
in the formula (I), the compound is shown in the specification,
Figure BDA0002994776060000133
the frequency domain expression of the stator current in the abc coordinate system is as follows:
Figure BDA0002994776060000134
Figure BDA0002994776060000135
Figure BDA0002994776060000136
in the formula
Figure BDA0002994776060000137
Wherein, Is1、IsnThe amplitudes of the current fundamental frequency positive sequence and negative sequence components at the stator end of the generator are respectively.
The frequency domain expression of the rotor current in the abc coordinate system is as follows:
Figure BDA0002994776060000138
Figure BDA0002994776060000139
Figure BDA00029947760600001310
in the formula (f)r＝ωr/2π；ωrAs angular speed of the rotor, fsIn order to obtain the slip frequency,
Figure BDA00029947760600001311
Figure BDA00029947760600001312
in which Ird、IrqD, q-axis components of the rotor current, I, respectivelyr1、IrnThe amplitudes of the current fundamental frequency positive sequence and negative sequence components at the rotor end of the generator are respectively.
S105, determining a GSC coordinate transformation matrix and an RSC coordinate transformation matrix by using a harmonic linearization method according to a phase-locked angle in a phase-locked loop in the doubly-fed induction generator system, as shown in fig. 3.
S105 specifically comprises the following steps:
using formulas
Figure BDA0002994776060000141
Determining a GSC coordinate transformation matrix;
wherein the content of the first and second substances,
Figure BDA0002994776060000142
Figure BDA0002994776060000143
Figure BDA0002994776060000151
Figure BDA0002994776060000152
Figure BDA0002994776060000153
Figure BDA0002994776060000154
in the formula HPLL(s)＝(Kpp+KpiS/s is a transfer function of the phase-locked loop including a PI regulator and an integrator, Kpp、KpiProportional, integral, V, of the PI regulator of the PLL1Is the grid voltage fundamental wave positive sequence amplitude.
Using a formula
Figure BDA0002994776060000155
Determining an RSC coordinate transformation matrix;
wherein the content of the first and second substances,
Figure BDA0002994776060000161
Figure BDA0002994776060000162
Figure BDA0002994776060000163
Figure BDA0002994776060000164
Figure BDA0002994776060000165
Figure BDA0002994776060000166
wherein, thetaPLLTo lock the phase angle, thetarIs the rotor position angle.
And S106, converting the three-phase current on the alternating current side of the GSC after the frequency domain is converted into a dq coordinate system according to the GSC coordinate conversion matrix, and further determining a dq component of a voltage command value output by the GSC.
S106 specifically includes:
using formulas
Figure BDA0002994776060000171
And formulas
Figure BDA0002994776060000173
And converting the three-phase current dq components on the alternating current side of the GSC after the frequency domain conversion.
As shown in fig. 4, using a formula
Figure BDA0002994776060000174
And formula
Figure BDA0002994776060000175
The dq component of the voltage command value of the GSC output is determined.
S107, converting the three-phase current flowing into the stator winding after the frequency domain conversion and the three-phase current flowing into the rotor winding after the frequency domain conversion into a dq coordinate system according to the RSC coordinate transformation matrix, and further determining a dq component of a voltage command value output by the RSC;
s107 specifically comprises the following steps:
using formulas
Figure BDA0002994776060000176
And formula
Figure BDA0002994776060000177
Perform frequency domain conversionConverting the dq components of the three-phase current flowing into the rotor winding;
as shown in fig. 5, using the formula
Figure BDA0002994776060000178
And formula
Figure BDA0002994776060000179
The dq component of the voltage command value of the RSC output is determined.
S108, determining an a-phase output voltage command value of the GSC in an abc coordinate system according to an inverse matrix of the GSC coordinate transformation matrix and a dq component of the voltage command value output by the GSC;
s108 specifically includes:
using formulas
Figure BDA0002994776060000181
Determining an inverse matrix of a GSC coordinate transformation matrix;
using formulas
Figure BDA0002994776060000182
And determining an a-phase output voltage command value of the GSC under an abc coordinate system.
Wherein, I* 1＝(Idref－jIqref)/2。
S109, determining an a-phase output voltage command value of the RSC in an abc coordinate system according to the inverse matrix of the RSC coordinate transformation matrix and the dq component of the voltage command value output by the RSC;
s109 specifically comprises:
using formulas
Figure BDA0002994776060000183
Determining an inverse matrix of the RSC coordinate transformation matrix;
using formulas
Figure BDA0002994776060000184
And determining an a-phase output voltage command value of RSC under an abc coordinate system.
Wherein, I* r1＝(Ird－jIrq)/2。
S110, determining a GSC direct current steady-state characteristic quantity according to the GSC output current, the relation between the voltage and the grid-connected point voltage under an abc static coordinate system, the three-phase voltage at the fan grid-connected point after the frequency domain is converted and an a-phase output voltage instruction value of the GSC under the abc coordinate system, and further determining a base frequency negative sequence impedance model of the GSC;
s110 specifically comprises:
using formulas
Figure BDA0002994776060000185
Determining a GSC direct current steady-state characteristic quantity;
using formulas
Figure BDA0002994776060000191
Determining a fundamental frequency negative sequence impedance model of the GSC;
before determining the above model, using a formula
Figure BDA0002994776060000192
And determining the relation between the fundamental frequency negative sequence voltage and the fundamental frequency negative sequence current of the GSC system. And determining the model according to the relation between the fundamental frequency negative sequence voltage and the fundamental frequency negative sequence current of the GSC system.
Wherein D is0And Q0For the steady state characterization of GSC direct current, V1Is the positive sequence amplitude, K, of the fundamental wave of the network voltagedq＝ω1L is GSC current loop coupling coefficient, L is GSC output filter inductance,
Figure BDA0002994776060000193
is a positive sequence component of the fundamental wave of the grid current, f1Is the fundamental frequency, j is the imaginary component of the complex number,
Figure BDA0002994776060000194
is the initial phase of the current fundamental wave, Hgi(2jω1) Is the transfer function, omega, of the network-side converter PI regulator at fundamental frequency1At fundamental angular velocity, I* 1＝(Idref－ jIqref) And/2 is the conjugate of the positive sequence fundamental current.
S111, determining RSC direct-current steady-state characteristic quantity according to the relation between RSC current, voltage and flux of a unit rotor side converter in an abc static coordinate system, the three-phase current flowing into a stator winding after frequency domain conversion, the three-phase current flowing into a rotor winding after frequency domain conversion and an a-phase output voltage instruction value of the RSC in the abc coordinate system, and further determining a fundamental frequency negative sequence impedance model of the RSC;
s111 specifically includes:
using formulas
Figure BDA0002994776060000195
Determining RSC direct current steady-state characterization quantity;
using formulas
Figure BDA0002994776060000196
Determining a fundamental frequency negative sequence impedance model of RSC;
before determining the model, the method further comprises:
using formulas
Figure BDA0002994776060000201
And determining the relationship between the fundamental frequency negative sequence voltage and the fundamental frequency negative sequence current of the controlled DFIG system, and further determining the model according to the relationship between the fundamental frequency negative sequence voltage and the fundamental frequency negative sequence current of the controlled DFIG system.
Wherein D isr0And Qr0Is a steady-state characterization quantity of RSC direct current, omegasIs the electrical angular velocity of the stator, Ird、IrqD, q-axis components of the rotor current, Krdq＝ωs(Lr－Lm 2/Ls) Is the RSC current loop decoupling coefficient, LmIs the mutual inductance value between stator and rotor windings, Ird、IrqD and q-axis components of the rotor current, Ir1The amplitude of the fundamental frequency positive sequence component of the current at the rotor end of the generator,
Figure BDA0002994776060000202
as an inductance of the rotor, there is a high inductance,
Figure BDA0002994776060000203
is stator inductance, Vsd，VsqIs the d, q axis component of the stator voltage, S ═ j ω1，F(2jω1) Being the transfer function of a phase-locked loop PI regulator at fundamental frequency, Hri(2jω1) For the transfer function of the rotor side converter PI regulator at fundamental frequency,
Figure BDA0002994776060000204
is the slip.
And S112, determining a negative sequence impedance model of the doubly-fed induction generator system according to the fundamental frequency negative sequence impedance model of the GSC and the fundamental frequency negative sequence impedance model of the controlled DFIG, and as shown in FIG. 6.
S112 specifically includes:
using formulas
Figure BDA0002994776060000205
Determining a negative sequence impedance model of the doubly-fed induction generator system;
wherein the content of the first and second substances,
Figure BDA0002994776060000206
is a negative sequence impedance model of a double-fed induction generator system,
Figure BDA0002994776060000207
being a fundamental negative-order impedance model of GSC,
Figure BDA0002994776060000208
is a fundamental frequency negative sequence impedance model of the controlled DFIG.
And S113, determining the fundamental frequency negative sequence impedance of the double-fed induction generator system according to the negative sequence impedance model of the double-fed induction generator system.
In order to verify the accuracy of the negative sequence impedance model of the doubly-fed induction generator system, the correctness of the negative sequence impedance model of the doubly-fed induction generator system is verified through time domain simulation by utilizing the built MTALAB doubly-fed induction generator system negative sequence impedance model; the calculation results and the time domain simulation results are collated into table 1, and the table 1 is as follows:
TABLE 1
Figure BDA0002994776060000211
As can be seen from Table 1, the error between the formula calculation result and the MATLAB time domain simulation result is very small, and the correctness of the negative sequence impedance model of the doubly-fed induction generator system is verified.
A double-fed induction generator system fundamental frequency negative sequence impedance determination system, comprising:
the parameter acquisition module is used for acquiring three-phase current and three-phase voltage of the alternating current side of a converter grid-side converter GSC in the doubly-fed induction generator system under an abc static coordinate system, GSC output filter inductance, three-phase voltage at a fan grid-connected point, three-phase current flowing into a stator winding, three-phase current flowing into a rotor winding, three-phase voltage of the stator winding, three-phase voltage of the rotor winding, a generator stator and a rotor turn ratio, resistance of a generator stator winding and resistance of a rotor winding translated to the stator side, a self-inductance matrix and a mutual inductance matrix of the generator stator and the rotor translated to the stator side;
the system comprises a relation determining module of GSC output current, voltage and grid-connected point voltage under an abc static coordinate system, wherein the relation determining module is used for determining the relation of the GSC output current, the voltage and the grid-connected point voltage under the abc static coordinate system according to three-phase current and three-phase voltage at the alternating current side of a grid-side converter GSC, GSC output filter inductance and three-phase voltage at a fan grid-connected point;
the generator set rotor side converter RSC current, voltage and flux linkage relation determination module under the abc static coordinate system is used for determining the relation of the RSC current, the voltage and the flux linkage of the generator set rotor side converter under the abc static coordinate system according to the three-phase current flowing into the stator winding, the three-phase current flowing into the rotor winding, the three-phase voltage of the stator winding, the three-phase voltage of the rotor winding, the turn ratio of a generator stator and a rotor, the resistance of the generator stator winding and the resistance of the rotor winding converted to the stator side, the self-inductance matrix of the generator stator and the rotor converted to the stator side and the mutual inductance matrix;
the frequency domain conversion module is used for converting the three-phase voltage at the grid-connected point of the fan, the three-phase current at the GSC alternating current side, the three-phase current flowing into the stator winding and the three-phase current flowing into the rotor winding from time domain to frequency domain;
the coordinate transformation matrix determining module is used for determining a GSC coordinate transformation matrix and an RSC coordinate transformation matrix by adopting a harmonic linearization method according to a phase locking angle in a phase locking loop in the double-fed induction generator system;
the voltage instruction value determining module is used for converting the three-phase current on the alternating current side of the GSC after the frequency domain conversion into a dq coordinate system according to the GSC coordinate conversion matrix so as to determine the dq component of the voltage instruction value output by the GSC;
the RSC output voltage command value determining module is used for converting the three-phase current flowing into the stator winding after the frequency domain conversion and the three-phase current flowing into the rotor winding after the frequency domain conversion into a dq coordinate system according to the RSC coordinate transformation matrix so as to determine the dq component of the RSC output voltage command value;
the device comprises an a-phase output voltage instruction value determining module of the GSC under an abc coordinate system, a data processing module and a data processing module, wherein the a-phase output voltage instruction value determining module is used for determining an a-phase output voltage instruction value of the GSC under the abc coordinate system according to an inverse matrix of a GSC coordinate transformation matrix and dq components of a voltage instruction value output by the GSC;
the RSC output voltage command value determining module is used for determining an a-phase output voltage command value of the RSC in the abc coordinate system according to an inverse matrix of the RSC coordinate transformation matrix and a dq component of the voltage command value output by the RSC;
the GSC fundamental frequency negative sequence impedance model determining module is used for determining GSC direct current steady-state characteristic quantity according to the relation between GSC output current, voltage and grid-connected point voltage under an abc static coordinate system, three-phase voltage at a fan grid-connected point after frequency domain conversion and a-phase output voltage instruction value of the GSC under the abc coordinate system, and further determining a GSC fundamental frequency negative sequence impedance model;
the RSC fundamental frequency negative sequence impedance model determining module is used for determining RSC direct current steady-state characteristic quantity according to the relation between RSC current, voltage and flux of the unit rotor side converter in the abc static coordinate system, three-phase current flowing into the stator winding after frequency domain conversion, three-phase current flowing into the rotor winding after frequency domain conversion and an a-phase output voltage instruction value of the RSC in the abc coordinate system, and further determining a fundamental frequency negative sequence impedance model of the controlled DFIG;
the double-fed induction generator system negative sequence impedance model determining module is used for determining a double-fed induction generator system negative sequence impedance model according to the GSC fundamental frequency negative sequence impedance model and the controlled DFIG fundamental frequency negative sequence impedance model;
and the double-fed induction generator system fundamental frequency negative sequence impedance determining module is used for determining the double-fed induction generator system fundamental frequency negative sequence impedance according to the double-fed induction generator system negative sequence impedance model.
The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other. For the system disclosed by the embodiment, the description is relatively simple because the system corresponds to the method disclosed by the embodiment, and the relevant points can be referred to the method part for description.
The principles and embodiments of the present invention have been described herein using specific examples, which are provided only to help understand the method and the core concept of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, the specific embodiments and the application range may be changed. In view of the above, the present disclosure should not be construed as limiting the invention.

Claims (8)

1. A method for determining the negative sequence impedance of the fundamental frequency of a double-fed induction generator system is characterized by comprising the following steps:
acquiring three-phase current and three-phase voltage at the alternating current side of a grid-side converter GSC (neutral grid side converter) of a doubly-fed induction generator system under an abc static coordinate system, GSC output filter inductance, three-phase voltage at a fan grid-connected point, three-phase current flowing into a stator winding, three-phase current flowing into a rotor winding, three-phase voltage of the stator winding, three-phase voltage of the rotor winding, a generator stator and rotor turn ratio, resistance of a generator stator winding and resistance of the rotor winding translated to the stator side, a self-inductance matrix and a mutual inductance matrix translated to the generator stator and the rotor at the stator side;
determining the relation between the GSC output current and voltage and the grid-connected point voltage under an abc static coordinate system according to the three-phase current and the three-phase voltage of the GSC AC side of the grid-side converter, the GSC output filter inductance and the three-phase voltage of the fan grid-connected point;
determining the relation of RSC current, voltage and flux linkage of a unit rotor side converter under an abc static coordinate system according to the three-phase current flowing into a stator winding, the three-phase current flowing into a rotor winding, the three-phase voltage of the stator winding, the three-phase voltage of the rotor winding, the resistance of a generator stator winding and the resistance of a rotor winding on the stator side, the self-inductance matrix and the mutual inductance matrix of the generator stator and the generator rotor on the stator side;
converting the three-phase voltage at the grid-connected point of the fan, the three-phase current at the GSC alternating current side, the three-phase current flowing into the stator winding and the three-phase current flowing into the rotor winding from time domain to frequency domain;
according to a phase locking angle in a phase locking loop in a double-fed induction generator system, determining a GSC coordinate transformation matrix and an RSC coordinate transformation matrix by adopting a harmonic linearization method;
converting the three-phase current on the GSC alternating current side after the frequency domain is converted into a dq coordinate system according to the GSC coordinate conversion matrix, and further determining the dq component of the voltage command value output by the GSC;
converting the three-phase current flowing into the stator winding after the frequency domain conversion and the three-phase current flowing into the rotor winding after the frequency domain conversion into a dq coordinate system according to the RSC coordinate transformation matrix, and further determining a dq component of a voltage command value output by the RSC;
determining an a-phase output voltage command value of the GSC under an abc coordinate system according to an inverse matrix of a GSC coordinate transformation matrix and a dq component of a voltage command value output by the GSC;
determining an a-phase output voltage command value of the RSC under an abc coordinate system according to an inverse matrix of the RSC coordinate transformation matrix and a dq component of a voltage command value output by the RSC;
determining a GSC direct-current steady-state characteristic quantity according to the relation between GSC output current, voltage and grid-connected point voltage under an abc static coordinate system, three-phase voltage at a fan grid-connected point after frequency domain conversion and an a-phase output voltage instruction value of the GSC under the abc coordinate system, and further determining a base frequency negative sequence impedance model of the GSC;
determining RSC direct current steady-state characteristic quantity according to the relation between RSC current, voltage and flux of a unit rotor side converter in an abc static coordinate system, three-phase current flowing into a stator winding after frequency domain conversion, three-phase current flowing into a rotor winding after frequency domain conversion and an a-phase output voltage command value of RSC in the abc coordinate system, and further determining a base frequency negative sequence impedance model of the controlled DFIG;
determining a negative-sequence impedance model of a doubly-fed induction generator system according to the fundamental frequency negative-sequence impedance model of the GSC and the fundamental frequency negative-sequence impedance model of the controlled DFIG;
and determining the fundamental frequency negative sequence impedance of the doubly-fed induction generator system according to the negative sequence impedance model of the doubly-fed induction generator system.
2. The method for determining the fundamental frequency negative sequence impedance of the doubly-fed induction generator system according to claim 1, wherein the relationship between the GSC output current and voltage and the grid-connected point voltage under the abc static coordinate system is determined according to the three-phase current and the three-phase voltage at the AC side of the grid-side converter GSC, the GSC output filter inductance and the three-phase voltage at the grid-connected point of the fan, and specifically comprises the following steps:
using a formula
Figure FDA0002994776050000021
Determining the relation between GSC output current, voltage and grid-connected point voltage under an abc static coordinate system;
using formulas
Figure FDA0002994776050000022
Converting positive, negative and zero sequence components;
wherein L is GSC output filter inductance, iga、igbAnd igcThree-phase current, v, on the alternating side of GSCa、vbAnd vcFor three-phase voltage, v, at the point of fan integrationia、vibAnd vicIs the three-phase voltage, i, of the GSC AC sideg1、ig2、ig0Is the positive, negative and zero sequence components of the GSC alternating side current vi1、vi2、vi0Is the positive, negative and zero sequence components of the GSC AC side voltage, v1、v2、v0The voltage of the fan grid-connected point is a positive, negative and zero sequence component.
3. The method for determining the fundamental frequency negative sequence impedance of the doubly-fed induction generator system according to claim 2, wherein the relationship between the RSC current, the voltage and the flux linkage of the unit rotor-side converter in the abc stationary coordinate system is determined according to the three-phase current flowing into the stator winding, the three-phase current flowing into the rotor winding, the three-phase voltage of the stator winding, the three-phase voltage of the rotor winding, the turn ratio of the generator stator and the rotor, the resistance of the generator stator winding and the resistance of the rotor winding converted to the stator side, the self-inductance matrix of the generator stator and the rotor converted to the stator side, and the mutual inductance matrix, and specifically comprises the following steps:
using formulas
Figure FDA0002994776050000031
Determining the relation among RSC current, voltage and flux linkage of a unit rotor side converter under an abc static coordinate system;
using formulas
Figure FDA0002994776050000032
Converting positive, negative and zero sequence components;
wherein v iss_abcFor three-phase voltage flowing into the stator winding, is_abcFor three-phase current flowing in the stator winding, vr_abcThree-phase voltage, i, for rotor windingsr_abcThree-phase currents, K, for rotor windingseFor the number ratio of stator and rotor turns of the generator,. psis_abcAnd psir_abcIs in abc coordinate systemMagnetic linkage, Lss、Lsr、LrsAnd LrrFor converting self-inductance matrix and mutual inductance matrix, R, of stator and rotor of generator to stator sides、RrFor conversion into the resistance of the stator and rotor windings of the generator on the stator side, vs_pnVoltage, v, expressed for positive and negative sequence of the statorr_pnVoltages represented by positive and negative sequences of the rotor, is_pnCurrent represented by positive and negative sequence of stator, ir_pnCurrent, psi, expressed as positive and negative sequence of the rotors_pnFlux linkage, psi, expressed for positive and negative order of the statorr_pnFlux linkage represented by the positive and negative sequence of the rotor.
4. The method for determining the fundamental frequency negative sequence impedance of the doubly-fed induction generator system as claimed in claim 3, wherein the step of determining the GSC coordinate transformation matrix and the RSC coordinate transformation matrix by using a harmonic linearization method according to a phase-locked angle in a phase-locked loop of the doubly-fed induction generator system specifically comprises:
using a formula
Figure RE-FDA0003115302040000041
Determining a GSC coordinate transformation matrix;
using a formula
Figure RE-FDA0003115302040000042
Determining an RSC coordinate transformation matrix;
wherein, thetaPLLTo lock the phase angle, thetarIs the rotor position angle.
5. The method for determining the fundamental frequency negative sequence impedance of the doubly-fed induction generator system according to claim 4, wherein the step of determining the GSC direct current steady-state characteristic quantity according to the relationship between the GSC output current and the voltage of the grid-connected point in the abc static coordinate system, the three-phase voltage of the wind turbine grid-connected point after the frequency domain conversion and the a-phase output voltage command value of the GSC in the abc coordinate system so as to determine the fundamental frequency negative sequence impedance model of the GSC specifically comprises the following steps:
using formulas
Figure FDA0002994776050000043
Determining a GSC direct current steady state characteristic quantity;
using formulas
Figure FDA0002994776050000044
Determining a fundamental negative sequence impedance model of the GSC;
wherein D is0And Q0For the steady-state characterization of GSC direct current, V1For positive sequence amplitude, K, of the fundamental wave of the network voltagedq＝ω1L is GSC current loop coupling coefficient, L is GSC output filter inductance,
Figure FDA0002994776050000045
is the positive sequence component of the fundamental wave of the power grid current,
Figure FDA0002994776050000046
is the initial phase of the fundamental wave of the current, f1Is the fundamental frequency, j is the imaginary complex component, Hgi(2jω1) Is the transfer function of the network-side converter PI regulator at fundamental frequency, F (2j omega)1) As a transfer function of the phase-locked loop PI regulator at fundamental frequency, omega1At fundamental angular velocity, I1 *＝(Idref－jIqref) And/2 is the conjugate of the positive sequence fundamental current.
6. The method for determining the fundamental frequency negative sequence impedance of the doubly-fed induction generator system according to claim 5, wherein the method for determining the RSC direct current steady-state characteristic quantity according to the relationship between the RSC current, the voltage and the flux of the generator set rotor side converter in the abc static coordinate system, the three-phase current flowing into the stator winding after the frequency domain conversion, the three-phase current flowing into the rotor winding after the frequency domain conversion and the a-phase output voltage command value of the RSC in the abc coordinate system so as to determine the fundamental frequency negative sequence impedance model of the RSC specifically comprises the following steps:
using formulas
Figure FDA0002994776050000051
Determining RSC direct current steady-state characterization quantity;
using formulas
Figure FDA0002994776050000052
Determining a fundamental frequency negative sequence impedance model of the RSC;
wherein D isr0And Qr0ω -A steady-state representation of RSCsIs the electrical angular velocity of the stator, Ird、IrqD, q-axis components of the rotor current, Krdq＝ωs(Lr－Lm 2/Ls) Is an RSC current loop decoupling coefficient, LmIs the mutual inductance value between stator and rotor windings, Ird、IrqD, q-axis components of the rotor current, I, respectivelyr1Is the amplitude of the current fundamental frequency positive sequence component at the rotor end of the generator,
Figure FDA0002994776050000053
as an inductance of the rotor, there is a high inductance,
Figure FDA0002994776050000054
is stator inductance, Vsd，VsqIs the d, q axis component of the stator voltage, S ═ j ω1，F(2jω1) Being the transfer function of a phase-locked loop PI regulator at fundamental frequency, Hri(2jω1) For the transfer function of the rotor side converter PI regulator at fundamental frequency,
Figure FDA0002994776050000055
is the slip.
7. The method for determining the negative-sequence impedance of the fundamental frequency of the doubly-fed induction generator system as claimed in claim 6, wherein the determining the negative-sequence impedance model of the doubly-fed induction generator system according to the negative-sequence impedance model of the fundamental frequency of the GSC and the negative-sequence impedance model of the fundamental frequency of the controlled DFIG specifically comprises:
using formulas
Figure FDA0002994776050000056
Determining a negative sequence impedance model of the double-fed induction generator system;
wherein the content of the first and second substances,
Figure FDA0002994776050000057
is a negative sequence impedance model of a double-fed induction generator system,
Figure FDA0002994776050000058
being a fundamental negative-sequence impedance model of GSC,
Figure FDA0002994776050000059
is a fundamental frequency negative sequence impedance model of the controlled DFIG.
8. A system for determining a negative sequence impedance of a fundamental frequency of a doubly-fed induction generator system, comprising:
the parameter acquisition module is used for acquiring three-phase current, three-phase voltage, GSC output filter inductance, three-phase voltage at a fan grid-connected point, three-phase current flowing into a stator winding, three-phase current flowing into a rotor winding, three-phase voltage of the stator winding, three-phase voltage of the rotor winding, the turn ratio of a generator stator and a rotor, the resistance of the generator stator winding and the resistance of the rotor winding translated to the stator side, a self-inductance matrix and a mutual inductance matrix of the generator stator and the rotor translated to the stator side in the double-fed induction generator system under an abc static coordinate system;
the system comprises a relation determining module for determining the relation between the GSC output current, the voltage and the grid-connected point voltage under the abc static coordinate system, wherein the relation determining module is used for determining the relation between the GSC output current, the voltage and the grid-connected point voltage under the abc static coordinate system according to the three-phase current and the three-phase voltage at the alternating current side of the grid-side converter GSC, the GSC output filter inductance and the three-phase voltage at the grid-connected point of the fan;
the device comprises a relation determining module for RSC current, voltage and flux linkage of the unit rotor side converter under the abc static coordinate system, wherein the relation determining module is used for determining the relation of RSC current, voltage and flux linkage of the unit rotor side converter under the abc static coordinate system according to three-phase current flowing into a stator winding, three-phase current flowing into a rotor winding, three-phase voltage of a stator winding, three-phase voltage of a rotor winding, a turn ratio of a generator stator and a rotor, resistance of the generator stator winding and the rotor winding converted to the stator side, a self-inductance matrix and a mutual inductance matrix of the generator stator and the rotor converted to the stator side;
the frequency domain conversion module is used for converting the three-phase voltage at the grid-connected point of the fan, the three-phase current at the GSC alternating current side, the three-phase current flowing into the stator winding and the three-phase current flowing into the rotor winding from time domain to frequency domain;
the coordinate transformation matrix determining module is used for determining a GSC coordinate transformation matrix and an RSC coordinate transformation matrix by adopting a harmonic linearization method according to a phase locking angle in a phase locking loop in the doubly-fed induction generator system;
the voltage command value determining module is used for converting the three-phase current on the alternating current side of the GSC after the frequency domain is converted into a dq coordinate system according to the GSC coordinate transformation matrix so as to determine the dq component of the voltage command value output by the GSC;
the RSC output voltage command value determining module is used for converting the three-phase current which flows into the stator winding and the three-phase current which flows into the rotor winding after the frequency domain is converted into a dq coordinate system according to the RSC coordinate transformation matrix so as to determine the dq component of the RSC output voltage command value;
the device comprises an a-phase output voltage instruction value determining module of the GSC in an abc coordinate system, a voltage instruction value determining module and a control module, wherein the a-phase output voltage instruction value determining module is used for determining an a-phase output voltage instruction value of the GSC in the abc coordinate system according to an inverse matrix of a GSC coordinate transformation matrix and a voltage instruction value output by the GSC;
the RSC control device comprises an a-phase output voltage instruction value determining module of the RSC in the abc coordinate system, and is used for determining an a-phase output voltage instruction value of the RSC in the abc coordinate system according to an inverse matrix of an RSC coordinate transformation matrix and a voltage instruction value output by the RSC;
the GSC fundamental frequency negative sequence impedance model determining module is used for determining GSC direct current steady-state characteristic quantity according to the relation between GSC output current, voltage and grid-connected point voltage under an abc static coordinate system, three-phase voltage at a fan grid-connected point after frequency domain conversion and a-phase output voltage instruction value of the GSC under the abc coordinate system, and further determining a GSC fundamental frequency negative sequence impedance model;
the RSC fundamental frequency negative sequence impedance model determining module is used for determining RSC direct current steady-state characteristic quantity according to the relation between RSC current, voltage and flux of the unit rotor side converter in the abc static coordinate system, the three-phase current flowing into the stator winding after the frequency domain is converted, the three-phase current flowing into the rotor winding after the frequency domain is converted and an a-phase output voltage instruction value of the RSC in the abc coordinate system, and further determining a fundamental frequency negative sequence impedance model of the RSC;
the double-fed induction generator system negative-sequence impedance model determining module is used for determining a double-fed induction generator system negative-sequence impedance model according to the GSC fundamental frequency negative-sequence impedance model and the controlled DFIG fundamental frequency negative-sequence impedance model;
and the double-fed induction generator system fundamental frequency negative sequence impedance determining module is used for determining the double-fed induction generator system fundamental frequency negative sequence impedance according to the double-fed induction generator system negative sequence impedance model.
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