CN114744640A - Distributed phase modulation machine sequence impedance modeling method - Google Patents

Distributed phase modulation machine sequence impedance modeling method Download PDF

Info

Publication number
CN114744640A
CN114744640A CN202210437766.0A CN202210437766A CN114744640A CN 114744640 A CN114744640 A CN 114744640A CN 202210437766 A CN202210437766 A CN 202210437766A CN 114744640 A CN114744640 A CN 114744640A
Authority
CN
China
Prior art keywords
phase
voltage
frequency
disturbance
grid
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
CN202210437766.0A
Other languages
Chinese (zh)
Inventor
薛安成
汪云涛
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
North China Electric Power University
Original Assignee
North China Electric Power University
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by North China Electric Power University filed Critical North China Electric Power University
Priority to CN202210437766.0A priority Critical patent/CN114744640A/en
Publication of CN114744640A publication Critical patent/CN114744640A/en
Pending legal-status Critical Current

Links

Images

Classifications

    • 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
    • H02J3/12—Circuit arrangements for ac mains or ac distribution networks for adjusting voltage in ac networks by changing a characteristic of the network load
    • H02J3/16—Circuit arrangements for ac mains or ac distribution networks for adjusting voltage in ac networks by changing a characteristic of the network load by adjustment of reactive power
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F30/00—Computer-aided design [CAD]
    • G06F30/20—Design optimisation, verification or simulation
    • 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
    • H02J3/18—Arrangements for adjusting, eliminating or compensating reactive power in networks
    • H02J3/1885—Arrangements for adjusting, eliminating or compensating reactive power in networks using rotating means, e.g. synchronous 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
    • 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
    • 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
    • H02J2300/22—The renewable source being solar energy
    • H02J2300/24—The renewable source being solar energy of photovoltaic origin
    • 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
    • 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
    • Y02E40/40—Arrangements for reducing harmonics

Abstract

The invention discloses a distributed phase modulator sequence impedance modeling method which comprises the steps of firstly, determining voltage and current information of a PCC point of a grid-connected point, and injecting voltage disturbance signals with positive sequence frequency and negative sequence frequency into the grid-connected point; secondly, deducing an expression of the electrical quantity in the main circuit in a frequency domain, and converting the grid connection point information from a three-phase natural coordinate system into a two-phase dq axis coordinate system through a phase-locked loop considering phase angle disturbance; thirdly, deducing a stator voltage component of the phase modulator through a phase-locked loop, an excitation control loop and a generator loop; then, acquiring a mathematical relation between the input disturbance quantity and each electric quantity disturbance signal, and converting each variable into a static natural coordinate system by utilizing Park inverse transformation; and finally, constructing a basic circuit equation according to the electrical structure at the grid-connected point, and acquiring the impedance expression of the distributed phase modulator under the positive sequence frequency and the negative sequence frequency by using ohm's law. The method has the advantages of simple design thought, clear physical concept, strong expansibility and the like, and has important theoretical significance and engineering value.

Description

Distributed phase modulation machine sequence impedance modeling method
Technical Field
The invention relates to the related field of distributed phase modulators, in particular to a distributed phase modulator sequence impedance modeling method.
Background
The new energy power generation in China is characterized by centralized development and long-distance transmission, and the characteristics of the new energy power generation are increasingly strengthened along with the large-scale development of an ultra-high voltage transmission technology. Wind, light and other new energy stations are usually located at the tail end of a power grid with weak structural connection, local loads cannot be effectively absorbed, a large amount of active power needs to be transmitted in a long distance, and a large amount of reactive power needs to be supported. The important reasons for the failure of the large-scale new energy unit to disconnect in recent years are as follows: and system voltage fluctuation and instability caused by insufficient dynamic reactive power regulation capacity. The typical process is as follows: the short-circuit fault of the electrical equipment causes the voltage of a near-area station to drop, and the Crowbar protection action of the wind turbine generator absorbs more reactive power from the power grid to induce other generators to be disconnected. The fault clearing and the unit part are disconnected, so that a large amount of reactive redundancy is caused, and the overvoltage disconnection phenomenon caused by the imbalance of the dynamic reactive power regulation capacity of the reactive compensation equipment is triggered.
In addition, the oscillation risk caused by the large-scale new energy source unit (wind, light and other equipment containing the power electronic converter) being connected to the power grid is more severe.
Aiming at accidents caused/participated in by the new energy unit, on one hand, a proper amount of reactive power needs to be provided for the new energy system, and on the other hand, inertia support needs to be provided for a high-proportion power electronic equipment unit with low inertia and low damping characteristics. The synchronous phase modulators with rapid dynamic response and certain system inertia can effectively improve the problems when being put into operation in the converter station, but the large phase modulators intensively arranged in the converter station are difficult to improve the voltage stability level of the low-voltage-level bus. The single machine capacity is below 50Mvar, and the distributed synchronous phase modulator connected in parallel at the 115kV side of the outlet of the new energy source unit has better economical efficiency and is beneficial to inhibiting the problem of voltage mutation of a low-voltage-level bus.
The sequence impedance modeling method under the static natural coordinate system has the unique advantages of clear physical significance, simple impedance form, capability of directly measuring impedance, wide application range and the like, is favorable for analyzing the impedance characteristics of the grid connection of the new energy unit, and further assists in researching the oscillation mechanism and the suppression method initiated/participated by the new energy unit. The distributed synchronous phase modulator is used as one of reactive compensation equipment, and the previous research does not consider establishing a distributed phase modulator model from the perspective of sequence impedance modeling.
The equivalent impedance model of the distributed phase modulator is established by adopting a sequence impedance modeling method based on harmonic linearization, which is beneficial to establishing a small signal equivalent model of a network-computer interaction system. And the method is researched based on a Nyquist criterion equal frequency domain stability analysis means. The method has the advantages of simple design thought, clear physical concept, strong expansibility and the like.
In view of the above, the invention is based on the idea of harmonic linearization, and performs sequence impedance modeling on a distributed phase modulator, and firstly, voltage disturbance signals with positive sequence and negative sequence frequencies are injected into a grid-connected point; secondly, converting the grid-connected point information from a three-phase natural coordinate system into a two-phase dq axis coordinate system through a phase-locked loop considering phase angle disturbance; thirdly, deducing a stator voltage component of the phase modulator under the action of a phase-locked loop, an excitation control loop and a generator loop; then, converting each variable to a static natural coordinate system by utilizing Park inverse transformation; and finally, constructing a basic circuit equation according to the electrical structure at the grid-connected point, and acquiring the impedance expression of the distributed phase modulator under the positive sequence frequency and the negative sequence frequency by using the ohm's law.
Disclosure of Invention
The invention aims to provide a distributed phase modulation machine sequence impedance modeling method aiming at the defects of the existing research content, and the distributed phase modulation machine sequence impedance model is determined under the condition of comprehensively considering a generator model, an excitation model and a phase-locked loop model. The method is beneficial to modeling of the machine-grid interactive system with the distributed phase modulators as reactive compensation equipment, and further provides theoretical support for the stability of the grid-connected system.
The purpose of the invention is realized by the following technical scheme:
a method of modeling distributed phase modulated machine sequence impedance, the method comprising:
step 1, determining parameters such as amplitude and phase of PCC point voltage and current of grid-connected point, and respectively injecting frequency f into each phasepWith a positive sequence harmonic disturbance voltage signal and a frequency of fnNegative sequence harmonic disturbance voltage signal;
step 2, deducing an expression of the electrical quantity in the main circuit in a frequency domain, and converting variables in a three-phase natural coordinate system into a two-phase dq rotating coordinate system by considering a Park transformation matrix of output disturbance of a phase-locked loop;
step 3, local transfer functions are deduced respectively for a phase-locked loop and an excitation control loop, and a stator voltage output equation is established based on a practical three-order model of the synchronous generator;
step 4, acquiring a mathematical relation between the input disturbance quantity and each electric quantity disturbance signal, and obtaining grid-connected point electric positive sequence and negative sequence voltages under a static natural coordinate system by considering Park inverse transformation of disturbance output by a phase-locked loop;
and 5, constructing a basic circuit equation according to the electrical structure at the grid-connected point, and acquiring the impedance expression of the distributed phase modulator under the positive sequence frequency and the negative sequence frequency by using the ohm's law.
Further, according to the technical scheme, when the injection frequency is f at the grid-connected PCC points respectivelypWith a positive sequence harmonic disturbance voltage signal and a frequency of fnWhen the negative sequence harmonic wave disturbs the voltage signal, the corresponding frequency is the fundamental frequency and f is generated in the phase-locked loop and the excitation control loop through the response of the control linkp-f1(or f)n+f1) With an excitation voltage component and corresponding frequency of fp-f1(or f)n+f1) The phase locked loop of (a) outputs the perturbed phase angle. Then the frequency segment is substituted into a synchronous generator model, and the frequency segment is subjected to Park inverse transformation of the phase angle output by a phase-locked loop containing disturbance to form a frequency segment containing f corresponding to the frequencypOf positive sequence phase voltage signal and frequency fnThe negative sequence phase voltage signal. The frequency component being substantially the fundamental frequency f1With a corresponding frequency of fp-f1The components of (a) are generated together.
According to the technical scheme provided by the invention, the method can determine the sequence impedance value of the distributed phase modulator in each frequency band, and has important theoretical significance and engineering value for analyzing the new energy grid-connected problem containing the distributed phase modulator based on an impedance analysis method.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the description below 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 creative efforts.
Fig. 1 is a schematic flow chart of a distributed phase modulation sequence impedance modeling method according to an embodiment of the present invention;
fig. 2 is a topology structure diagram of a distributed phase modulator according to an embodiment of the present invention;
fig. 3 is a block diagram illustrating excitation control of a distributed phase modulator according to an embodiment of the present invention;
fig. 4 is a frequency characteristic of a real part and an imaginary part of a positive sequence impedance of a distributed phase modulator according to an embodiment of the present invention;
fig. 5 shows real-part and imaginary-part frequency characteristics of negative-sequence impedance of the distributed phase modulator according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention are 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 embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the present invention without making any creative effort, shall fall within the protection scope of the present invention.
The embodiments of the present invention will be further described in detail with reference to the accompanying drawings, and the specific analysis process is as follows:
step 1, determining parameters such as amplitude and phase of PCC point voltage and current of grid-connected point, and respectively injecting frequency f into each phasepWith a positive sequence harmonic disturbance voltage signal and a frequency of fnNegative sequence harmonic disturbance voltage signal;
fig. 2 shows a topology diagram of a grid-connected distributed phase modulator. Due to three-phase symmetry, analysis of partial variables and derivation of related expressions in the modeling process are mainly shown by the A phase.
At the moment, the instantaneous values of the A-phase voltage and the current at the grid-connected point are set as follows:
Figure RE-GDA0003669586280000031
Figure RE-GDA0003669586280000032
in the formula (f)1、fp、fnAre respectively fundamental waveFrequency, positive sequence disturbance signal frequency, negative sequence disturbance signal frequency. U shape1、Up、UnThe amplitude of the fundamental frequency voltage, the amplitude of the positive sequence disturbance voltage and the amplitude of the negative sequence disturbance voltage are respectively. I is1、Ip、InThe amplitude of the fundamental frequency current, the amplitude of the positive sequence disturbance current and the amplitude of the negative sequence disturbance current are respectively. u. upcca、ipccaThe voltage and the current instantaneous value of the grid-connected point A phase are respectively.
Figure RE-GDA0003669586280000033
The phase angles of the corresponding signals under the fundamental frequency, the positive sequence frequency and the negative sequence frequency are respectively. It is noted that the magnitude of the positive-sequence and negative-sequence disturbance voltages does not exceed 10% of the fundamental voltage, and the phase angle of the voltage signal at the fundamental frequency is generally set as the reference phase angle.
Step 2, deducing an expression of the electrical quantity in the main circuit in a frequency domain, and converting variables in a three-phase natural coordinate system into a two-phase dq rotating coordinate system by considering a Park transformation matrix of output disturbance of a phase-locked loop;
the expression of the main circuit electrical quantity response under the frequency is as follows:
Figure RE-GDA0003669586280000041
Figure RE-GDA0003669586280000042
considering the phase-locked loop disturbance, the phase angle of the phase-locked loop output is as follows:
Figure RE-GDA0003669586280000043
wherein theta is1(t) is the positive rotational phase angle instantaneous value produced by the fundamental frequency component,
Figure RE-GDA0003669586280000044
for phase-locked loop reference phase information, oneGeneral provisions for
Figure RE-GDA0003669586280000045
Δ θ (t) is a disturbance angle, which is related to the q-axis component of the voltage, and is expressed by the following formula:
Figure RE-GDA0003669586280000046
at the moment, voltage signals under a three-phase natural coordinate system are converted into a two-phase dq rotating coordinate system by considering a Park transformation matrix of phase-locked loop output disturbance, wherein a frequency domain expression of a grid-connected point d-axis voltage component is as follows:
Figure RE-GDA0003669586280000047
step 3, local transfer functions are deduced respectively for a phase-locked loop and an excitation control loop, and a stator voltage output equation is established based on a practical three-order model of the synchronous generator;
in a pll loop, as in equation (6), the pll transfer function g(s) is expressed as:
Figure RE-GDA0003669586280000048
Figure RE-GDA0003669586280000049
in the FV type field control loop circuit, the detailed control block diagram is shown in FIG. 3, wherein VTFor the voltage measurement on the high voltage side of the transformer, V is generally considered during the calculationT＝Upccd，TRFor the regulator input filter time constant, VREFIs a voltage reference. K. KV、T1、T2、T3、T4Adjusting selection factors for regulator gain, proportional integral or pure integral respectively and four voltage regulators in different linksAnd (4) counting. KA、TA、KF、TFThe gain and time constant of the voltage regulating amplifier and the gain and time constant of the voltage regulating stabilizer are respectively. KCFor commutating the load factor of the reactance rectifier, VAMAX、VAMIN、VA1MAX、VA1MINIs the regulator internal clipping. VRMAX、VRMINClipping is output for the regulator. I isf、EfIs the exciting current and voltage of synchronous machine.
The excitation control loop transfer function is as follows:
Figure RE-GDA0003669586280000051
Figure RE-GDA0003669586280000052
Figure RE-GDA0003669586280000053
further, the grid-connected point current is converted from a three-phase natural coordinate system into a two-phase dq rotation coordinate system, and the frequency expression of the grid-connected point current is as follows:
Figure RE-GDA0003669586280000054
Figure RE-GDA0003669586280000055
the grid-connected point current is the generator stator current of the synchronous phase modulator, so that a practical third-order model is written for the generator:
Figure RE-GDA0003669586280000056
wherein, Usd、UsqRespectively, the generator stator voltage dq axis components. RaIs the stator resistance of the phase modifier generator. Xd、 Xq、Xd' are direct axis synchronous reactance, quadrature axis synchronous reactance, and direct axis transient reactance, respectively. T isd0' is the direct axis transient open time constant.
From the above equation, the frequency domain expression of the electrical quantity can be written as follows:
Figure RE-GDA0003669586280000061
Figure RE-GDA0003669586280000062
step 4, acquiring a mathematical relation between the input disturbance quantity and each electric quantity disturbance signal, and obtaining grid-connected point electric positive sequence and negative sequence voltages under a three-phase natural coordinate system by considering Park inverse transformation of disturbance output by a phase-locked loop;
for the disturbance existing in the phase-locked loop, when performing inverse Park transform, the following simplification can be performed:
Figure RE-GDA0003669586280000063
the corresponding frequency expression is as follows:
Figure RE-GDA0003669586280000064
the Park inverse transformation process is as follows:
Figure RE-GDA0003669586280000065
in summary, a voltage frequency domain expression shown in the following formula can be obtained, taking the a-phase voltage at the positive sequence frequency as an example:
Figure RE-GDA0003669586280000071
and 5, constructing a basic circuit equation according to the electrical structure at the grid-connected point, and acquiring the impedance expression of the distributed phase modulator under the positive sequence frequency and the negative sequence frequency by using the ohm's law.
The following basic equations can be established as in fig. 2:
Usa[f]-Upcca[f]＝sLIpcca[f] (22)
and finally, obtaining positive sequence and negative sequence impedance expressions of the distributed synchronous phase modulator according to ohm's law:
Figure RE-GDA0003669586280000072
Figure RE-GDA0003669586280000073
particularly, considering that in an actual system, the voltage value of the grid-connected point is often close to the reference value, and the measurement link has a smaller time constant, the partial links in the formulas (23) and (24) can be simplified. A simplified impedance model is formed as shown below, taking the positive sequence impedance as an example:
Figure RE-GDA0003669586280000074
further, in order to verify the accuracy of the distributed phase modulation sequence impedance modeling in the steps (23) and (24), a PSCAD electromagnetic transient simulation model is built. In the simulation model, the main parameters of each main circuit and control loop are set as shown in table 1. Injecting a disturbance voltage signal at the high-voltage side of the transformer, sampling 44 frequency points within the range of 10-100Hz in the frequency sweeping process, focusing on the response near the power frequency of 50Hz, sequentially obtaining an impedance real part (resistance per unit value) and an imaginary part (reactance per unit value) of a grid-connected port of the phase modulator system under a positive sequence and a negative sequence, and comparing the impedance real part (resistance per unit value) and the imaginary part (reactance per unit value) with a theoretical calculation model. The comparative figures are shown in fig. 4 and 5.
The comparison results of fig. 4 and fig. 5 show that the positive sequence impedance theoretical calculation model and the negative sequence impedance theoretical calculation model of the distributed phase modulator are basically consistent with the simulated sweep frequency value, and the accuracy of theoretical calculation is verified.
TABLE 1 distributed phase Modulator simulation model principal parameters
Figure RE-GDA0003669586280000081
It is noted that those skilled in the art will recognize that embodiments of the present invention are not described in detail herein.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims (6)

1. A method of modeling distributed phase modulated machine sequence impedance, the method comprising:
step 1, determining parameters such as amplitude and phase of PCC point voltage and current of grid-connected point, and respectively injecting frequency f into each phasepWith a positive sequence harmonic disturbance voltage signal and a frequency of fnNegative sequence harmonic disturbance voltage signal of (a);
step 2, deducing an expression of the electrical quantity in the main circuit in a frequency domain, and converting variables in a three-phase natural coordinate system into a two-phase dq rotating coordinate system by considering a Park transformation matrix of output disturbance of a phase-locked loop;
step 3, local transfer functions are deduced respectively for a phase-locked loop and an excitation control loop, and a stator voltage output equation is established based on a practical three-order model of the synchronous generator;
step 4, acquiring a mathematical relation between the input disturbance quantity and each electric quantity disturbance signal, and obtaining grid-connected point electric positive sequence voltage and grid-connected point electric negative sequence voltage under a static natural coordinate system by considering Park inverse transformation of disturbance output by a phase-locked loop;
and 5, constructing a basic circuit equation according to the electrical structure at the grid-connected point, and acquiring the impedance expression of the distributed phase modulator under the positive sequence frequency and the negative sequence frequency by using the ohm's law.
2. The distributed phase modulation sequence impedance modeling method according to claim 1, characterized in that: in the step 1, parameters such as amplitude and phase of the voltage and the current of the PCC point of the grid-connected point are determined, and the injection frequency of each phase is fpWith a positive sequence harmonic disturbance voltage signal and a frequency of fnNegative sequence harmonic disturbance voltage signal;
at the moment, the instantaneous values of the A-phase voltage and the current at the grid-connected point are set as follows:
Figure FDA0003613335360000011
Figure FDA0003613335360000012
in the formula (f)1、fp、fnThe frequency of the fundamental wave, the frequency of the positive sequence disturbance signal and the frequency of the negative sequence disturbance signal are respectively; u shape1、Up、UnRespectively a fundamental frequency voltage amplitude, a positive sequence disturbance voltage amplitude and a negative sequence disturbance voltage amplitude; i is1、Ip、InRespectively a fundamental frequency current amplitude, a positive sequence disturbance current amplitude and a negative sequence disturbance current amplitude; u. ofpcca、ipccaRespectively representing the voltage and current instantaneous values of the grid-connected point A phase;
Figure FDA0003613335360000013
the phase angles of corresponding signals under the fundamental frequency, the positive sequence frequency and the negative sequence frequency respectively; it is noted that the amplitude of the positive-sequence and negative-sequence disturbance voltages does not exceed 10% of the fundamental frequency voltage, and the phase angle of the voltage signal at the fundamental frequency is generalSet as the reference phase angle.
3. The distributed phase modulation sequence impedance modeling method according to claim 1, characterized in that: in the step 2, deriving an expression of the electrical quantity in the main circuit in a frequency domain, and converting variables in a three-phase natural coordinate system into a two-phase dq rotating coordinate system by considering a Park transformation matrix of output disturbance of a phase-locked loop;
the expression of the main circuit electrical quantity response under the frequency is as follows:
Figure FDA0003613335360000021
Figure FDA0003613335360000022
considering the phase-locked loop disturbance, the phase angle of the phase-locked loop output is as follows:
Figure FDA0003613335360000023
wherein theta is1(t) is the positive rotational phase angle instantaneous value produced by the fundamental frequency component,
Figure FDA0003613335360000024
for phase-locked loop reference phase information, provision is generally made for
Figure FDA0003613335360000025
Δ θ (t) is a disturbance angle, and is related to the q-axis component of the voltage, and is expressed by the following formula:
Figure FDA0003613335360000026
at the moment, voltage signals under a three-phase natural coordinate system are converted into a two-phase dq rotating coordinate system by considering a Park transformation matrix of phase-locked loop output disturbance, wherein a frequency domain expression of a grid-connected point d-axis voltage component is as follows:
Figure FDA0003613335360000027
the above equation is a frequency domain expression of the voltage component of the d-axis of the grid-connected point.
4. The distributed phase modulation sequence impedance modeling method according to claim 1, characterized in that: in the step 3, local transfer functions are deduced respectively for a phase-locked loop and an excitation control loop, and a stator voltage output equation is established based on a practical third-order model of the synchronous generator;
in a pll loop, as in equation (6), the pll transfer function g(s) is expressed as:
Figure FDA0003613335360000028
Figure FDA0003613335360000029
in FV type excitation control loop, detailed control block diagram is shown in FIG. 3, wherein VTFor the voltage measurement on the high-voltage side of the transformer, V is generally considered during the calculationT＝Upccd，TRFor the regulator input filter time constant, VREFIs a voltage reference value; K. k isV、T1、T2、T3、T4Adjusting selection factors for gain, proportional integral or pure integral of the regulator and four voltage regulator time constants in different links respectively; kA、TA、KF、TFRespectively gain and time constant of the voltage regulating amplifier and gain and time constant of the voltage regulating stabilizer; kCFor commutating the load factor of the reactance rectifier, VAMAX、VAMIN、VA1MAX、VA1MINLimiting the amplitude of the interior of the regulator; vRMAX、VRMINLimiting the output amplitude of the regulator; i isf、EfExciting current and exciting voltage for the synchronous machine;
the excitation control loop transfer function is as follows:
Figure FDA0003613335360000031
Figure FDA0003613335360000032
Figure FDA0003613335360000033
further, the grid-connected point current is converted from a three-phase natural coordinate system into a two-phase dq rotation coordinate system, and the frequency expression of the grid-connected point current is as follows:
Figure FDA0003613335360000034
Figure FDA0003613335360000035
the grid-connected point current is the generator stator current of the synchronous phase modulator, so that a practical third-order model is written for the generator:
Figure FDA0003613335360000036
wherein, Usd、UsqRespectively, the generator stator voltage dq axis components; raIs the stator resistance of the phase modulator generator; xd、Xq、Xd' direct axis synchronous reactance, quadrature axis synchronous respectivelyReactance, direct axis transient reactance; t isd0' is the direct axis transient open circuit time constant; from the above equation, the frequency domain expression of the electrical quantity can be written as follows:
Figure FDA0003613335360000041
Figure FDA0003613335360000042
the above expression is a frequency domain expression of the dq axis component of the generator stator voltage.
5. The distributed phase modulation sequence impedance modeling method according to claim 1, characterized in that: in the step 4, acquiring a mathematical relation between the input disturbance quantity and each electric quantity disturbance signal, and obtaining the grid-connected point electric positive sequence voltage and the grid-connected point electric negative sequence voltage under a three-phase natural coordinate system by considering Park inverse transformation of disturbance output by the phase-locked loop;
for the disturbance existing in the phase-locked loop, when performing inverse Park transform, the following simplification can be performed:
Figure FDA0003613335360000043
the corresponding frequency expression is as follows:
Figure FDA0003613335360000044
the Park inverse transformation process is as follows:
Figure FDA0003613335360000045
in summary, a voltage frequency domain expression shown in the following formula can be obtained, taking the a-phase voltage at the positive sequence frequency as an example:
Figure FDA0003613335360000051
other phase voltage frequency domain expressions resemble phase a.
6. The distributed phase modulation sequence impedance modeling method according to claim 1, characterized in that: in the step 5, a basic circuit equation is constructed according to the electrical structure at the grid-connected point, and the impedance expression of the distributed phase modulator under the positive sequence frequency and the negative sequence frequency is obtained by using ohm's law;
the following basic equations can be established as in fig. 2:
Usa[f]-Upcca[f]＝sLIpcca[f] (22)
and finally, obtaining positive sequence and negative sequence impedance expressions of the distributed synchronous phase modulator according to ohm's law:
Figure FDA0003613335360000052
Figure FDA0003613335360000053
particularly, considering that in an actual system, the voltage value of the grid-connected point is often close to the reference value, and the measuring link has a smaller time constant, the parent part links in the formulas (23) and (24) can be simplified; a simplified impedance model is formed as shown below, taking the positive sequence impedance as an example:
Figure FDA0003613335360000054
equation (25) is a simplified impedance model, taking the positive sequence impedance as an example.
CN202210437766.0A 2022-04-25 2022-04-25 Distributed phase modulation machine sequence impedance modeling method Pending CN114744640A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202210437766.0A CN114744640A (en) 2022-04-25 2022-04-25 Distributed phase modulation machine sequence impedance modeling method

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202210437766.0A CN114744640A (en) 2022-04-25 2022-04-25 Distributed phase modulation machine sequence impedance modeling method

Publications (1)

Publication Number Publication Date
CN114744640A true CN114744640A (en) 2022-07-12

Family

ID=82282748

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202210437766.0A Pending CN114744640A (en) 2022-04-25 2022-04-25 Distributed phase modulation machine sequence impedance modeling method

Country Status (1)

Country Link
CN (1) CN114744640A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116470569A (en) * 2023-03-31 2023-07-21 中国电力科学研究院有限公司 Method and device for determining dynamic impedance interval of full-power wind turbine generator

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116470569A (en) * 2023-03-31 2023-07-21 中国电力科学研究院有限公司 Method and device for determining dynamic impedance interval of full-power wind turbine generator

Similar Documents

Publication Publication Date Title
Xue et al. A complete impedance model of a PMSG-based wind energy conversion system and its effect on the stability analysis of MMC-HVDC connected offshore wind farms
Song et al. Analysis of middle frequency resonance in DFIG system considering phase-locked loop
Hu et al. Impedance characteristic analysis and stability improvement method for DFIG system within PLL bandwidth based on different reference frames
CN108847669B (en) Multi-synchronous rotation coordinate system-based multifunctional grid-connected inverter harmonic treatment method
CN107732939B (en) Subsynchronous oscillation suppression control method based on voltage source type converter decoupling control
CN111525611A (en) Frequency coupling effect-considering doubly-fed grid-connected system subsynchronous oscillation analysis method
Kheshti et al. Modeling and fault analysis of doubly fed induction generators for gansu wind farm application
CN110676874B (en) Direct-drive fan subsynchronous oscillation electrical quantity analysis method considering frequency coupling effect
CN112165115B (en) Parameter identification method and device for ash box model of direct-drive wind turbine generator
CN112542855A (en) Modeling and simulation method for phasor model of double-fed wind power generation system
Liu et al. Complex impedance-based frequency coupling characteristics analysis of DFIG-based WT during asymmetric grid faults
CN106026175B (en) A kind of time-domain matrix modeling method of full rank dual feedback wind power generation system
CN114744640A (en) Distributed phase modulation machine sequence impedance modeling method
CN109494722B (en) Power grid side equivalent impedance modeling method and system
Ma et al. An active damping control method for direct-drive wind farm with flexible DC transmission system based on the remodeling of dynamic energy branches
Li et al. Stability assessment and enhanced control of DFIG-based WTs during weak AC grid
CN107480406B (en) Dynamic vector model building method for calculating short-circuit current of double-fed wind turbine generator
Xue et al. A complete impedance model of a PMSG-Based wind turbine system considering machine-side dynamics
Zhang et al. Harmonic filtering in DFIG-based offshore wind farm through resonance damping
CN107994565A (en) The emulation mode and its system of a kind of THE UPFC
Chen et al. Suppression Strategy of Subsynchronous Oscillation Based on Dynamic Voltage Compensation Control for Grid-Forming D-PMSG in Weak Grid
Chen et al. Analysis of wide-band oscillation characteristics of rudong offshore wind farm connected to the grid through VSC-based DC transmission system
Zhang Analysis and control of resonances in HVDC connected DFIG-based offshore wind farm
Li et al. Parallel impedance-reshaping control strategy for suppressing wide range high-frequency resonance of shunt compensated DFIG system
Wang et al. Design of static synchronous compensator and its controller based on improved ip-iq detection method

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination