CN114123346B - General DFF-SAI phase locking method under positive sequence rotation coordinate system - Google Patents
General DFF-SAI phase locking method under positive sequence rotation coordinate system Download PDFInfo
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- H—ELECTRICITY
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- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/26—Arrangements for eliminating or reducing asymmetry in polyphase networks
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
- H02J3/40—Synchronising a generator for connection to a network or to another generator
- H02J3/44—Synchronising a generator for connection to a network or to another generator with means for ensuring correct phase sequence
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
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- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
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Abstract
The invention relates to the technical field of synchronous tracking of power grids, in particular to a universal DFF-SAI phase locking method under a positive sequence rotation coordinate system, which extracts three-phase voltages; clark conversion and three-phase voltageT'Conversion to obtain signals containing multiple harmonicsd'、q'A component; will bed'、q'The components obtain positive sequence multiple harmonic signals through a DFF-SAI unit; performing Park transformation on the positive sequence multiple harmonic signals to obtain a positive sequence rotation coordinate systemdqAn axis component; by means ofqThe shaft component is subjected to a phase locking link to obtain the angular frequency and the phase angle of the harmonic signal; the angular frequency of the subharmonic signal is taken as a given amount of the angular frequency of the DFF-SAI unit; according todThe information of the amplitude, the frequency and the phase angle of the positive sequence component of the fundamental wave of the power grid is determined by the shaft component, the frequency of the harmonic signal and the phase angle; the method realizes accurate locking of the harmonic signal and the fundamental positive sequence component, and is applicable to both ideal and non-ideal working conditions of the power grid.
Description
Technical Field
The invention relates to the technical field of synchronous tracking of power grids, in particular to a universal DFF-SAI phase locking method under a positive sequence rotation coordinate system.
Background
The power grid synchronization technology can realize tracking and locking of the phase of alternating current signals, and can also provide information such as frequency and amplitude of related signals when necessary, and is a key technology for tracking and locking the power grid when the converter is connected. The power grid synchronization technology comprises a zero crossing detection technology, a power grid synchronization technology based on discrete Fourier transformation, a power grid synchronization technology based on a neural network, a recursively weighted least square estimation algorithm, a Kalman filtering technology, a frequency locking technology and a phase locking technology.
The most widely applied power grid synchronization technology is a phase locking technology at present, the phase locking technology comprises an open loop phase locking method and a closed loop phase locking method, and the open loop phase locking method has the defects of low phase locking precision, low response speed, sensitivity to a non-ideal power grid and the like, so that the closed loop phase locking method is generally adopted in the actual grid-connected application of the converter. In view of the importance of the closed-loop phase-locked loop, more and more students have studied the closed-loop phase-locked loop, and many control and design schemes of the closed-loop phase-locked loop are proposed, so that the performance of the phase-locked loop is also improved and improved continuously.
Under the power grid balance working condition, the most widely applied closed-loop phase-locked loop method is a traditional synchronous rotation coordinate system phase-locked loop (synchronous rotating frame phase locked loop, SRF-PLL) method. When the power grid is in the balanced working condition, the power grid voltage only has positive sequence components, and the traditional SRF-PLL can accurately track the synchronous signals of the power grid voltage at the moment. To cope with the unbalanced condition of the power grid, various phase-locked loop methods have been proposed successively, including an improved SRF-PLL with added filter, an Enhanced PLL (EPLL), a decoupled dual synchronous reference frame PLL (Decoupled Double Synchronous Reference Frame PLL, DDSRF-PLL), a multiple reference frame-based PLL (Multiple Reference Frame PLL, MRF-PLL), an adaptive notch-based PLL (Adaptive Notch Filter PLL, ANF-PLL), a bi-second order generalized integrator-based PLL (Dual Second Order Generalized Integrator PLL, DSOGI-PLL), a delay signal-based PLL (Delayed Signal Cancellation PLL, DSC-PLL), a sine-magnitude integrator-based PLL (Sinusoidal Amplitude Integrator PLL, SAI-PLL), a complex filter-based PLL (Complex Coefficient Filter PLL, CCF-PLL), a moving average filter-based PLL (Moving Average Filters PLL, MAF-PLL), and Tan-Sun coordinate transformation-based PLL.
In order to improve the accuracy and the rapidity of the phase-locked loop for tracking the power grid synchronous signal, the invention provides a universal DFF-SAI phase-locking method under a positive sequence rotation coordinate system. In addition, the method provided by the invention can rapidly and accurately track the synchronous signal of the power grid voltage under the balanced working condition, and can rapidly and accurately acquire the synchronous signal of the power grid voltage under the non-ideal power grid working conditions such as three-phase unbalance, voltage single-phase amplitude drop or sudden rise, power grid single-phase loss, phase angle mutation working condition and the like, thereby greatly widening the application range of the phase-locked loop and improving the accuracy and rapidity of tracking the synchronous signal of the power grid.
For example, the 2-frequency-multiplication phase locking method disclosed in the chinese patent No. cn201510502220. X is based on two band-pass filters to extract 2-frequency-multiplication ac quantity so as to implement 2-frequency-multiplication phase locking, which is different from the basic principle of the frequency-multiplication phase locking method using DFF-SAI unit proposed in the present invention.
For another example, the 2-frequency-multiplication phase locking method disclosed in the 2-frequency-multiplication power grid synchronous phase locking method based on the second-order generalized integrator SOGI in the power grid voltage unbalance is based on the optimized SOGI-QSG to extract the 2-frequency-multiplication alternating current quantity so as to realize phase locking, and the basic principle of the 2-frequency-multiplication phase locking method adopting the DFF-SAI unit is different from that of the 2-frequency-multiplication phase locking method provided by the invention.
For example, in the paper of novel 2-frequency-multiplication phase locking technology based on sine amplitude integrator, the disclosed 2-frequency-multiplication phase locking method is based on a negative rotation coordinate system, 2-frequency-multiplication phase locking is completed by applying cascading SOGI and SAI, the phase locking method is based on a positive sequence rotation coordinate system, frequency-multiplication phase locking is completed by only adopting a positive sequence separation and extraction link of DFF-SAI, the basic principles of the two are different, and the method provided by the patent is simple in structure and good in rapidity.
The positive sequence rotation coordinate system, the SAI unit and the positive and negative sequence separation and extraction are common general knowledge in the phase locking technical field, the invention does not apply for protection of the individual links, but applies for protection of the frequency multiplication phase-locked loop method which contains the links and consists of the links, and the basic principle of the frequency multiplication phase-locked loop method is different from that of other traditional phase-locked loop methods and the basic principle of the disclosed phase-locked loop method.
Disclosure of Invention
The invention aims to provide a frequency multiplication phase-locked loop method which is universal for ideal and non-ideal power grids and is applicable to power grid voltage balance, power grid voltage unbalance, single-phase amplitude drop or sudden rise of power grid voltage, single-phase loss of power grid voltage and phase angle abrupt change working conditions and is based on a positive sequence rotation coordinate system and adopts a DFF-SAI unit, so that synchronous signals of power grid voltage can be tracked rapidly and accurately, and phase synchronization with power grid voltage is realized.
In order to achieve the above purpose, the present invention provides the following technical solutions:
a general DFF-SAI phase locking method under a positive sequence rotation coordinate system comprises the following steps:
step 1: acquiring a three-phase power grid voltage signal;
step 2: obtaining a multiple harmonic component signal, constructing a new transformation matrix T ' and a new coordinate system dq ' to obtain the multiple harmonic signal, transforming the three-phase static abc coordinate system to the dq ' coordinate system according to the three-phase grid voltage by utilizing the transformation matrix T ' to obtain a d ' axis voltage component v containing the multiple harmonic component d 'and q' axis voltage component v q 'transform matrix T' is
Step 3: extracting positive sequence multiple harmonic component signals; according to the d' axis voltage component v containing the harmonic component d 'and q' axis voltagesComponent v q ' separating and extracting positive sequence multiple harmonic components by using a DFF-SAI and a positive and negative sequence separation and extraction unit;
step 4: acquiring a positive sequence dq axis component under a positive sequence rotation coordinate system; according to the positive order multiple harmonic component, obtaining a d-axis voltage component v under a positive order dq rotating coordinate system through Park transformation d And q-axis voltage component v q ；
Step 5: acquiring phase synchronization information corresponding to angular frequency of the harmonic wave and the harmonic wave, and rotating the q-axis voltage component v under the coordinate system according to the positive sequence dq q The phase-locked loop can be used for locking the angular frequency of the harmonic wave and the phase angle synchronous information corresponding to the harmonic wave, so that the tracking and locking of the harmonic wave component are realized; the harmonic angular frequency is used as the angular frequency required by the DFF-SAI unit; the phase angle corresponding to the multiple harmonic frequency is a transformation angle, and the transformation angle is used for Park transformation when the positive sequence dq axis component is acquired;
step 6: acquiring the synchronous information of the amplitude, the phase and the frequency of the fundamental wave positive sequence component of the power grid; the d-axis voltage component v in the coordinate system is rotated according to the positive sequence dq d The synchronous information of the amplitude of the fundamental wave positive sequence component of the power grid can be obtained; according to the frequency of the harmonic wave angle and the phase angle corresponding to the harmonic wave frequency, the synchronous information of the frequency and the phase angle of the positive sequence component of the fundamental wave of the power grid can be obtained; phase angle of positive sequence component of fundamental wave of power grid as d' axis voltage component v of determined subharmonic signal d 'and q' axis voltage component v q ' transformation angle at time; i.e. the transformation angle of the transformation matrix T'; according to the obtained synchronous information of the amplitude, the phase and the frequency of the fundamental wave positive sequence component of the power grid, the tracking and the locking of the fundamental wave positive sequence component are realized, and therefore the signal synchronization of an ideal power grid and a non-ideal power grid is realized.
The technical scheme of the invention is further improved as follows: in the step 2, a novel matrix T' is constructed, and the matrix can convert the unbalanced three-phase voltage positive sequence component into positive sequence frequency multiplication alternating current quantity, namely positive sequence subharmonic component; the method specifically comprises the following steps:
by means of a three-phase network voltage signal v a v b v c ] T Left-hand T abc/αβ Matrix, threeThe phase grid voltage vector is transformed from a three-phase static abc coordinate system to a two-phase static alpha beta coordinate system to obtain two-phase alternating voltage v under the alpha beta coordinate system α And v β ；
The phase angle of the positive sequence component of the fundamental wave of the power grid is used as a transformation angle for the two-phase alternating current voltage v under an alpha beta coordinate system α And v β T 'transforming to obtain d' axis voltage component v containing multiple harmonic component d 'and q' axis voltage component v q '；
Transformation matrix T for transforming three-phase static abc coordinate system into two-phase static alpha beta coordinate system abc/αβ Is that
The technical scheme of the invention is further improved as follows: in step 3, positive sequence harmonic components are extracted to complete frequency multiplication phase locking, and after the three-phase power grid voltage is subjected to T ' transformation, a two-phase voltage v ' containing positive sequence harmonic components converted from voltage positive sequence components and direct current components converted from voltage negative sequence components can be obtained ' d And v' q To extract the positive sequence component and the subharmonic component, v 'is calculated' d And v' q The phase locking is finished by using the positive sequence component and the negative sequence component of the DFF-SAI through a positive sequence extraction and separation unit; the method specifically comprises the following steps:
the d' axis voltage component v containing the harmonic component d 'and q' axis voltage component v q ' as an input signal to the DFF-SAI unit, an alternating current quantity v is output through the DFF-SAI unit dt ' and v qt ' AC quantity v dt ' and v qt ' comprising: the DFF-SAI unit fully utilizes the angular frequency of the obtained multiple harmonic signal, and takes the angular frequency as a given quantity of the angular frequency required by the DFF-SAI unit, so that the DFF-SAI unit can rapidly and accurately extract the positive sequence multiple harmonic component;
traffic volume v dt ' and v qt ' input quantity as positive and negative sequence separation and extraction unit, input quantity through positive and negative sequence separation and extraction unitTraffic volume v dac ' and v qac ' and DC quantity v ddc ' and v qdc ' AC quantity v dac ' and v qac ' is positive order multiple harmonic component, DC quantity v ddc ' and v qdc ' is a negative sequence direct current component.
The technical scheme of the invention is further improved as follows: in step 5, the tracking and locking of the harmonic signal are frequency-doubled and phase-locked according to the q-axis voltage component v q The phase-locked loop can be used for locking the angular frequency of the harmonic wave and the phase angle synchronous information corresponding to the harmonic wave, so that the tracking and locking of the harmonic wave component are realized; the method specifically comprises the following steps:
the q-axis voltage component v in the positive sequence dq rotation coordinate system q As input signal, through PI regulator, adding with 200 PI to determine angular frequency of harmonic component;
and (3) integrating the harmonic angular frequency, then performing remainder processing with 2 pi, and determining a phase angle corresponding to the harmonic frequency.
The technical scheme of the invention is further improved as follows: in step 6, tracking and locking the positive sequence component of the fundamental wave of the power grid are locked by frequency multiplication according to the voltage component v of the d axis d The synchronous information of the amplitude of the positive sequence component of the fundamental wave of the power grid is obtained, and the synchronous information of the frequency and the phase angle of the positive sequence component of the fundamental wave of the power grid can be obtained according to the angular frequency of the harmonic wave and the phase angle corresponding to the frequency of the harmonic wave; the method specifically comprises the following steps:
the d-axis voltage component v in the coordinate system is rotated according to the positive sequence dq d As an output signal v d Can be used to represent the amplitude information of the positive sequence component of the fundamental wave of the network, i.e. by means of the output signal v d The amplitude of the positive sequence component of the fundamental wave of the power grid is tracked;
after 1/2 operation is carried out on the angular frequency of the multiple harmonic wave, determining the angular frequency information of the positive sequence component of the fundamental wave of the power grid;
and (3) carrying out integral operation on the angular frequency of the positive sequence component of the fundamental wave of the power grid, and then carrying out remainder taking processing on the angular frequency and 2 pi, so as to determine the phase angle information of the positive sequence component of the fundamental wave of the power grid.
Compared with the prior art, the general DFF-SAI phase locking method under the positive sequence rotation coordinate system has the following beneficial effects:
1. the invention provides a general DFF-SAI phase locking method under a positive sequence rotation coordinate system, which is characterized in that under the positive sequence rotation coordinate system, a transformation matrix T' is constructed to obtain a multiple harmonic signal, a DFF-SAI positive sequence negative separation and extraction unit is adopted to extract the positive sequence multiple harmonic signal, and a phase locking link is utilized to obtain the frequency and phase angle information of the multiple harmonic signal, so as to track and lock the multiple harmonic signal; in the process, the amplitude, frequency and phase synchronization information of the positive sequence fundamental component of the power grid can be obtained through tracking the harmonic signals, so that the positive sequence fundamental component of the power grid is tracked and locked, and the aim of synchronizing with the voltage phase of the power grid is fulfilled.
2. The invention provides a general DFF-SAI phase locking method under a positive sequence rotation coordinate system, which realizes tracking and locking of power grid voltage based on frequency multiplication phase locking of a harmonic signal, and has fast transient response speed and good accuracy compared with the traditional phase locking method based on phase locking of a fundamental frequency signal; the phase locking method adopts the DFF-SAI positive and negative sequence separation and extraction unit to obtain the positive sequence multiple harmonic signal to realize frequency multiplication phase locking under the positive sequence rotation coordinate system, and the method has simple result and small calculated amount.
3. The invention provides a general DFF-SAI phase locking method under a positive sequence rotation coordinate system, which is not only suitable for ideal power grid working conditions, but also suitable for non-ideal power grid working conditions such as unbalanced power grid voltage, single-phase amplitude drop or sudden rise of power grid voltage, single-phase loss of power grid voltage and phase angle mutation working conditions, and has universality; the synchronous information acquisition device has the characteristics of simple and compact structure, small operand, excellent performance, good dynamic performance of a control system and wide application range, and can rapidly and accurately acquire the synchronous information of the power grid voltage so as to realize phase synchronization with the power grid voltage.
4. The invention provides a general DFF-SAI phase locking method under a positive sequence rotation coordinate system, which generates frequency multiplication alternating current quantity, namely a harmonic component after unbalanced three-phase voltage is subjected to coordinate transformation, the traditional phase locking method filters or discards the harmonic component, but the invention utilizes the harmonic component to complete frequency multiplication phase locking, rapidly and accurately locks the harmonic angular frequency and fundamental angular frequency of the power grid voltage, obtains the synchronous information of amplitude, frequency and phase of the power grid voltage, and realizes the phase synchronization with the power grid voltage; the method is suitable for non-ideal power grid working conditions, and is also suitable for ideal power grid working conditions, including power grid voltage balance, power grid voltage unbalance, power grid voltage single-phase amplitude drop or sudden rise, power grid single-phase loss and phase angle jump working conditions.
Drawings
In order to more clearly illustrate the embodiments of the invention or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, it being obvious that the drawings in the following description are only some embodiments of the invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a block diagram of a frequency-doubling phase locking method according to the present invention.
Fig. 2 is a block diagram of a conventional SRF-PLL.
Fig. 3 is a block diagram of a 2-frequency-doubling phase-locking method based on optimized SOGI-QSG.
Fig. 4 is a block diagram of a 2-frequency-multiplication phase-locking method based on cascading SOGI and SAI.
Fig. 5 is a block diagram of a DFF-SAI unit according to the method of the present invention.
Fig. 6 is a block diagram of the positive and negative sequence extracting and separating unit in the method according to the present invention.
Detailed Description
The technical scheme of the present invention will be clearly and completely described in the following detailed description. It will be apparent that the described embodiments are only some, but not all, embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
As shown in FIG. 1, the overall structure diagram of the frequency doubling phase locking method is provided, and the main steps of the frequency doubling phase locking method comprise three-phase power grid voltage extraction, clark conversion, T' conversion, DFF-SAI units, positive and negative sequence separation and extraction links, park conversion and phase locking links. The phase locking link obtains the frequency of the harmonic signal as frequency information required by the DFF-SAI unit, the harmonic frequency is subjected to integral operation to obtain the corresponding phase angle of the harmonic signal as a conversion angle of Park conversion, the frequency of the harmonic signal is multiplied by 1/2 to obtain the frequency information of the fundamental wave positive sequence component of the power grid, and the frequency of the fundamental wave positive sequence component is subjected to integral operation to obtain the corresponding phase angle as a conversion angle of T' conversion.
A general DFF-SAI phase locking method under a positive sequence rotation coordinate system comprises the following steps:
step 1: acquiring a three-phase power grid voltage signal;
step 2: acquiring a harmonic component signal; unlike the conventional method for acquiring the harmonic components, the acquisition of the harmonic signals is realized by constructing a new transformation matrix T 'and constructing a new coordinate system dq' coordinate system. Transforming from a three-phase static abc coordinate system to a dq ' coordinate system according to the three-phase power grid voltage by using a transformation matrix T ' to obtain a d ' axis voltage component v containing a multiple harmonic component d 'and q' axis voltage component v q 'transform matrix T' is
Conventional methods of acquiring the harmonic components include fourier decomposition methods and fast fourier decomposition methods.
By means of a three-phase network voltage signal v a v b v c ] T Left-hand T abc/αβ Matrix, transforming the three-phase power grid voltage vector from the three-phase static abc coordinate system to the two-phase static alpha beta coordinate system to obtain the two-phase alternating voltage v under the alpha beta coordinate system α And v β Wherein T is abc/αβ Is that
For alpha beta coordinate systemTwo-phase ac voltage v α And v β T' transformation, i.e. [ v ] α v β ] T Multiplying the T 'matrix to obtain d' axis voltage component v containing harmonic components d 'and q' axis voltage component v q 'wherein T' is
Angle changeable->
The phase angle corresponding to the positive sequence component of the fundamental wave of the power grid.
Step 3: extracting positive sequence multiple harmonic component signals; according to the d' axis voltage component v containing the harmonic component d 'and q' axis voltage component v q ' the DFF-SAI and positive and negative sequence separation and extraction units are utilized to separate and extract positive sequence multiple harmonic components.
The d' axis voltage component v containing the harmonic component d 'and q' axis voltage component v q ' as an input signal to the DFF-SAI unit, an alternating current quantity v is output through the DFF-SAI unit dt ' and v qt ' AC quantity v dt ' and v qt ' comprising: an ac component identical to the input ac component and a dc component linearly related to the input dc component;
traffic volume v dt ' and v qt ' as input quantity of positive and negative sequence separation and extraction unit, output alternating current quantity v through positive and negative sequence separation and extraction unit dac ' and v qac ' and DC quantity v ddc ' and v qdc ' AC quantity v dac ' and v qac ' is positive order multiple harmonic component, DC quantity v ddc ' and v qdc ' is a negative sequence direct current component.
Step 4: acquiring a positive sequence dq axis component under a positive sequence rotation coordinate system; according to the positive order multiple harmonic component, the d-axis voltage component v under the positive order dq rotating coordinate system can be obtained through Park transformation d And q-axis voltage component v q 。
The positive sequence multiple harmonic component alternating current flow v dac ' and v qac ' as input signal, also subjected to Park conversionIs the positive order multiple harmonic component v dac 'v qac '] T Left-hand T αβ/dq Matrix, obtain d-axis voltage component v under positive sequence dq rotation coordinate system d And q-axis voltage component v q ，T αβ/dq The matrix is
Angle changeable->
Is the phase angle corresponding to the harmonic signal.
Step 5: acquiring phase synchronization information corresponding to the angular frequency of the harmonic wave; the q-axis voltage component v in the coordinate system is rotated according to the positive sequence dq q The phase-locked loop can be used for locking the angular frequency of the harmonic wave and the phase angle synchronous information corresponding to the harmonic wave, so that the tracking and locking of the harmonic wave component are realized; the harmonic angular frequency is used as the angular frequency required by the DFF-SAI unit; the phase angle corresponding to the harmonic frequency is a conversion angle, which is a conversion angle for Park conversion when the positive-order dq-axis component is obtained.
The q-axis voltage component v in the positive sequence dq rotation coordinate system q As input signal, through PI regulator, adding with 200 PI to determine angular frequency of harmonic component;
integrating the angular frequency of the multiple harmonic wave, then performing remainder processing with 2 pi, and determining a phase angle corresponding to the multiple harmonic wave frequency;
step 6: acquiring the synchronous information of the amplitude, the phase and the frequency of the fundamental wave positive sequence component of the power grid; the d-axis voltage component v in the coordinate system is rotated according to the positive sequence dq d The synchronous information of the amplitude of the fundamental wave positive sequence component of the power grid can be obtained; according to the frequency of the harmonic wave angle and the phase angle corresponding to the harmonic wave frequency, the synchronous information of the frequency and the phase angle of the positive sequence component of the fundamental wave of the power grid can be obtained; phase angle of positive sequence component of fundamental wave of power grid as d' axis voltage component v of determined subharmonic signal d 'and q' axis voltage component v q ' transformation angle at time; according to the obtained synchronous information of the amplitude, the phase and the frequency of the fundamental wave positive sequence component of the power grid, the method canTracking and locking of fundamental wave positive sequence components are realized; the d-axis voltage component v in the coordinate system is rotated according to the positive sequence dq d As an output signal v d Can be used to represent the amplitude information of the positive sequence component of the fundamental wave of the network, i.e. by means of the output signal v d The amplitude of the positive sequence component amplitude of the fundamental wave of the power grid can be tracked; after 1/2 operation is carried out on the angular frequency of the multiple harmonic wave, the angular frequency information of the positive sequence component of the fundamental wave of the power grid can be determined; and (3) carrying out integral operation on the angular frequency of the positive sequence component of the fundamental wave of the power grid, and then carrying out remainder taking processing on the angular frequency and 2 pi, so as to determine the phase angle information of the positive sequence component of the fundamental wave of the power grid.
As shown in fig. 2, a conventional SRF-PLL structure block diagram is shown, and the main steps are to extract three-phase power grid voltage, transform three-phase voltage vector from three-phase static abc coordinate system to two-phase rotation dq coordinate system through Clark transformation and Park transformation, obtain d-axis voltage component and q-axis voltage component, output quantity of q-axis passes through PI regulator, frequency information of power grid voltage can be obtained, and after integral operation, phase angle information of power grid voltage is obtained, so as to realize tracking and locking of power grid voltage. The phase locking method shown in fig. 2 is to complete phase locking by using a fundamental frequency signal, but the method provided by the patent obtains a multiple harmonic signal by constructing a transformation matrix T' and carries out frequency multiplication phase locking based on the multiple harmonic signal, and finally realizes tracking and locking of positive sequence fundamental components of the power grid voltage, which are quite different. Compared with the traditional SRF-PLL, the method provided by the patent has the advantages of high transient response speed, good accuracy and wide application range, and is suitable for not only ideal power grid working conditions, but also non-ideal power grid working conditions such as unbalanced power grid voltage, single-phase amplitude drop or sudden rise of power grid voltage, single-phase loss of power grid voltage and phase angle mutation working conditions.
As shown in FIG. 3, the 2-frequency-multiplication phase locking method based on optimized SOGI-QSG mainly comprises the steps of extracting three-phase voltage to perform Clark transformation to obtain two-phase alternating voltage v under an alpha beta coordinate system α And v β The method comprises the steps of carrying out a first treatment on the surface of the Then T 'is carried out' + Transforming to obtain two-phase voltage v 'containing multiple harmonic component' d And v' q The method comprises the steps of carrying out a first treatment on the surface of the The optimized SOGI-QSG treatment is carried out to obtain two perfect positive directionsAnd (3) carrying out Park conversion on the crossed harmonic signals to obtain dq axis voltage components under a dq coordinate system, obtaining angular frequency information of the harmonic waves by the output quantity of the q axis through a PI regulator, carrying out integral operation to obtain phase angle information corresponding to the harmonic signals, and obtaining the phase angle information of the positive sequence component of the fundamental wave of the power grid through 1/2 processing. The 2-frequency-multiplication phase locking method shown in fig. 3 belongs to the research result in the subject group, is a 2-frequency-multiplication phase locking thought and method based on a subharmonic signal, and is a frequency-multiplication phase locking method based on a subharmonic signal, while the method shown in fig. 3 is based on an optimized SOGI-QSG, and the basic principle of the method is different from that of the method shown in fig. 3 by adopting a DFF-SAI positive-negative sequence separation and extraction unit to extract positive-sequence subharmonic components and complete phase locking; in addition, compared with the method shown in fig. 3, the method provided by the patent has a wide application range, and is suitable for not only ideal power grid working conditions, but also non-ideal power grid working conditions such as unbalanced power grid voltage, single-phase amplitude drop or sudden rise of power grid voltage, single-phase loss of power grid voltage and phase angle abrupt change working conditions.
As shown in FIG. 4, the method is a block diagram of 2-frequency-multiplication phase locking method based on cascading SOGI and SAI, and comprises the main steps of extracting three-phase voltage to perform Clark transformation to obtain two-phase alternating voltage v under alpha beta coordinate system α And v β The method comprises the steps of carrying out a first treatment on the surface of the Will v α And v β Filtering through cascading SOGI to obtain purer two-phase alternating current quantity v' α And v' β The method comprises the steps of carrying out a first treatment on the surface of the And then v' α And v' β Through negative sequence rotation coordinate transformation, the dq axis voltage component v 'under the negative sequence dq rotation coordinate system is obtained' d And v' q Wherein v' d And v' q Contains a harmonic component; then v' d And v' q Obtaining positive sequence component v through SAI positive and negative sequence separation and extraction unit dac And v qac And negative sequence component v ddc And v qdc The method comprises the steps of carrying out a first treatment on the surface of the And finally, tracking and locking the harmonic component and the positive sequence component of the fundamental wave of the power grid by using a phase locking link. The 2-frequency-multiplication phase locking method shown in fig. 4 belongs to the research result in the subject group and is a 2-frequency-multiplication phase lock based on a harmonic signalThe phase locking method is also a frequency multiplication phase locking method based on a multiple harmonic signal, however, the method shown in fig. 4 is based on a cascading type SOGI and SAI positive and negative sequence separation and extraction unit in a negative sequence rotation coordinate system, the method is based on a positive sequence rotation coordinate system, only adopts a DFF-SAI positive and negative sequence separation and extraction unit to extract positive sequence multiple harmonic components and completes phase locking, and the basic principle of the method is different from that of the method shown in fig. 4; in addition, compared with the method shown in fig. 4, the method provided by the patent has the advantages of simple and compact structure, small operand and high transient response speed.
FIG. 5 is a block diagram showing a DFF-SAI unit in the method according to the present invention, in which three-phase voltages are converted by T ' to obtain two-phase alternating voltages v ' containing multiple harmonic signals ' d And v' q Will v' d And v' q As the input signal of the DFF-SAI unit, the non-static-difference tracking of the positive sequence harmonic component can be realized, and the purpose of extracting the positive sequence harmonic component and the negative sequence direct current component is achieved. In addition, the DFF-SAI unit fully utilizes the angular frequency of the harmonic signal obtained by the method, and the angular frequency is used as a given quantity of the angular frequency required by the DFF-SAI unit.
As shown in FIG. 6, the positive and negative sequence separation and extraction unit in the method of the present invention can be used to separate and extract two-phase voltage v' d And v' q The medium positive sequence harmonic component is separated from the negative sequence direct current component to obtain a positive sequence harmonic component v dac ' and v qac ' and negative sequence direct current component v ddc ' and v qdc ' the positive sequence subharmonic component can be further utilized to carry out frequency multiplication phase locking.
The above embodiments are merely illustrative of the preferred embodiments of the present invention and are not intended to limit the scope of the present invention, and various modifications and improvements made by those skilled in the art to the technical solutions of the present invention should fall within the protection scope defined by the claims of the present invention without departing from the design spirit of the present invention.
Claims (5)
1. The universal DFF-SAI phase locking method under the positive sequence rotation coordinate system is characterized by comprising the following steps:
step 1: acquiring a three-phase power grid voltage signal;
step 2: acquiring a harmonic component signal; constructing a new transformation matrix T ' and a new coordinate system dq ' to acquire the harmonic signals, and transforming the transformation matrix T ' from a three-phase static abc coordinate system to the dq ' coordinate system according to the three-phase grid voltage to obtain a d ' axis voltage component v containing the harmonic components d 'and q' axis voltage component v q 'transform matrix T' is
Step 3: extracting positive sequence multiple harmonic component signals; according to the d' axis voltage component v containing the harmonic component d 'and q' axis voltage component v q ' separating and extracting positive sequence multiple harmonic components by using a DFF-SAI and a positive and negative sequence separation and extraction unit;
step 4: acquiring a positive sequence dq axis component under a positive sequence rotation coordinate system; according to the positive order multiple harmonic component, obtaining a d-axis voltage component v under a positive order dq rotating coordinate system through Park transformation d And q-axis voltage component v q ；
Step 5: acquiring phase synchronization information corresponding to the angular frequency of the harmonic wave; the q-axis voltage component v in the coordinate system is rotated according to the positive sequence dq q The phase-locked loop can be used for locking the angular frequency of the harmonic wave and the phase angle synchronous information corresponding to the harmonic wave, so that the tracking and locking of the harmonic wave component are realized; the harmonic angular frequency is used as the angular frequency required by the DFF-SAI unit; the phase angle corresponding to the multiple harmonic frequency is a transformation angle, and the transformation angle is used for Park transformation when the positive sequence dq axis component is acquired;
step 6: acquiring the synchronous information of the amplitude, the phase and the frequency of the fundamental wave positive sequence component of the power grid; according to the positive sequenced-axis voltage component v in dq rotation coordinate system d The synchronous information of the amplitude of the fundamental wave positive sequence component of the power grid can be obtained; according to the frequency of the harmonic wave angle and the phase angle corresponding to the harmonic wave frequency, the synchronous information of the frequency and the phase angle of the positive sequence component of the fundamental wave of the power grid can be obtained; phase angle of positive sequence component of fundamental wave of power grid as d' axis voltage component v of determined subharmonic signal d 'and q' axis voltage component v q ' transformation angle at time; i.e. the transformation angle of the transformation matrix T'; according to the obtained synchronous information of the amplitude, the phase and the frequency of the fundamental wave positive sequence component of the power grid, the tracking and the locking of the fundamental wave positive sequence component are realized, and therefore the signal synchronization of an ideal power grid and a non-ideal power grid is realized.
2. The method for phase locking of a universal DFF-SAI in a positive rotation coordinate system according to claim 1, wherein: in the step 2, a novel matrix T' is constructed, and the matrix can convert the unbalanced three-phase voltage positive sequence component into positive sequence frequency multiplication alternating current quantity, namely positive sequence subharmonic component; the method specifically comprises the following steps:
by means of a three-phase network voltage signal v a v b v c ] T Left-hand T abc/αβ Matrix, transforming the three-phase power grid voltage vector from the three-phase static abc coordinate system to the two-phase static alpha beta coordinate system to obtain the two-phase alternating voltage v under the alpha beta coordinate system α And v β ；
The phase angle of the positive sequence component of the fundamental wave of the power grid is used as a transformation angle for the two-phase alternating current voltage v under an alpha beta coordinate system α And v β T 'transforming to obtain d' axis voltage component v containing multiple harmonic component d 'and q' axis voltage component v q '；
Transformation matrix T for transforming three-phase static abc coordinate system into two-phase static alpha beta coordinate system abc/αβ Is that
3. The method for phase locking of universal DFF-SAI in a positive rotation coordinate system as recited in claim 1, wherein the method comprises the steps of: in step 3, positive sequence harmonic components are extracted to complete frequency multiplication phase locking, and after the three-phase power grid voltage is subjected to T ' transformation, a two-phase voltage v ' containing positive sequence harmonic components converted from voltage positive sequence components and direct current components converted from voltage negative sequence components is obtained ' d And v' q To extract the positive sequence component and the subharmonic component, v 'is calculated' d And v' q The phase locking is finished by using the positive sequence component and the negative sequence component of the DFF-SAI through a positive sequence extraction and separation unit; the method specifically comprises the following steps:
the d' axis voltage component v containing the harmonic component d 'and q' axis voltage component v q ' as an input signal to the DFF-SAI unit, an alternating current quantity v is output through the DFF-SAI unit dt ' and v qt ' AC quantity v dt ' and v qt ' comprising: the DFF-SAI unit fully utilizes the angular frequency of the obtained multiple harmonic signal, and takes the angular frequency as a given quantity of the angular frequency required by the DFF-SAI unit, so that the DFF-SAI unit can rapidly and accurately extract the positive sequence multiple harmonic component;
traffic volume v dt ' and v qt ' as input quantity of positive and negative sequence separation and extraction unit, output alternating current quantity v through positive and negative sequence separation and extraction unit dac ' and v qac ' and DC quantity v ddc ' and v qdc ' AC quantity v dac ' and v qac ' is positive order multiple harmonic component, DC quantity v ddc ' and v qdc ' is a negative sequence direct current component.
4. The method for phase locking of a universal DFF-SAI in a positive rotation coordinate system according to claim 1, wherein: in step 5, the tracking and locking of the harmonic signal are frequency-doubled and phase-locked according to the q-axis voltage component v q The phase-locked loop can be used for locking the angular frequency of the harmonic wave and the phase angle synchronous information corresponding to the harmonic wave, so that the tracking and locking of the harmonic wave component are realized; the method specifically comprises the following steps:
the q-axis voltage component v in the positive sequence dq rotation coordinate system q As input signal, through PI regulator, adding with 200 PI to determine angular frequency of harmonic component;
and (3) integrating the harmonic angular frequency, then performing remainder processing with 2 pi, and determining a phase angle corresponding to the harmonic frequency.
5. The method for phase locking of a universal DFF-SAI in a positive rotation coordinate system according to claim 1, wherein: in step 6, tracking and locking the positive sequence component of the fundamental wave of the power grid are locked by frequency multiplication according to the voltage component v of the d axis d The synchronous information of the amplitude of the positive sequence component of the fundamental wave of the power grid is obtained, and the synchronous information of the frequency and the phase angle of the positive sequence component of the fundamental wave of the power grid can be obtained according to the angular frequency of the harmonic wave and the phase angle corresponding to the frequency of the harmonic wave; the method specifically comprises the following steps:
the d-axis voltage component v in the coordinate system is rotated according to the positive sequence dq d As an output signal v d Is representative of the amplitude information of the positive sequence component of the fundamental wave of the network, i.e. by the output signal v d The amplitude of the positive sequence component of the fundamental wave of the power grid is tracked;
after 1/2 operation is carried out on the angular frequency of the multiple harmonic wave, determining the angular frequency information of the positive sequence component of the fundamental wave of the power grid;
and (3) carrying out integral operation on the angular frequency of the positive sequence component of the fundamental wave of the power grid, and then carrying out remainder taking processing on the angular frequency and 2 pi, so as to determine the phase angle information of the positive sequence component of the fundamental wave of the power grid.
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