CN113162047B - Power spring multifunctional control method based on cascade generalized integrator - Google Patents

Power spring multifunctional control method based on cascade generalized integrator Download PDF

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CN113162047B
CN113162047B CN202110363757.7A CN202110363757A CN113162047B CN 113162047 B CN113162047 B CN 113162047B CN 202110363757 A CN202110363757 A CN 202110363757A CN 113162047 B CN113162047 B CN 113162047B
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power spring
voltage
generalized integrator
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CN113162047A (en
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丘东元
邱培程
张波
陈艳峰
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South China University of Technology SCUT
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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
    • H02J3/01—Arrangements for reducing harmonics or ripples
    • 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
    • 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
    • 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
    • H02J3/24—Arrangements for preventing or reducing oscillations of power in networks
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • 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]
    • 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
    • Y02E40/30—Reactive power compensation
    • 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

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Abstract

The invention discloses a power spring multifunctional control method based on a cascade generalized integrator, which comprises the following steps of: the voltage outer ring is controlled by proportional integral to obtain an active current reference value of the power spring; obtaining a key load current fundamental component and an orthogonal signal thereof through a cascade generalized integrator, and then forming a power spring voltage reference signal through a current control module and a voltage control module; the voltage inner ring is subjected to multiple quasi-proportional resonance control to obtain an inductive current reference signal of the power spring; the current inner loop adopts proportion control, the output of the current inner loop forms a modulation wave signal after passing through an amplitude limiter, and the modulation wave signal is compared with a carrier signal to generate a switching tube driving signal. The method can ensure the stability of the voltage of the key load and effectively inhibit the current harmonic waves of the power grid; meanwhile, reactive compensation can be provided, and the power factor of the power grid is improved. The invention does not introduce a low-pass filtering link, improves the detection real-time performance, and can obtain better dynamic performance by the system.

Description

Power spring multifunctional control method based on cascade generalized integrator
Technical Field
The invention relates to the application field of power electronics in a power system, in particular to a power spring multifunctional control method based on a cascade generalized integrator.
Background
The gradual exhaustion of fossil energy and the attention of people on environmental protection lead to the rapid development of renewable energy. The intermittent and random nature of renewable energy power generation makes the generated energy difficult to predict, and this can cause the mismatching of power demand and electric wire netting energy supply, and then causes user side load voltage unstable, seriously influences user side load's normal use. With the large-scale and high-proportion integration of renewable energy power generation into the power grid, a large number of power electronic devices are connected into the power grid, and serious harmonic pollution is caused to the power grid.
The power spring can effectively solve the problem of unstable voltage at the load side caused by power fluctuation of a power grid. On one hand, the existing electric spring control mainly focuses on realizing a single function of the electric spring, and on the aspect of multifunctional control of the electric spring, the existing research is relatively less; on the other hand, the harmonic Suppression control of the conventional power spring has its limitations, and Wang et al in the document "harmonic Suppression for Critical Loads Using Electric Springs With Current-Source Inverters" adopts a low-pass filtering link to realize the harmonic Suppression function of the power spring, and has the disadvantages of slow response speed, phase offset and the like. In the document "Enhancing Power Quality and Stability of Future Smart Grid with Intermittent Energy Sources Using Electric Springs", Parag Kanjiya et al uses a second-order generalized integrator to detect harmonic components on a critical load voltage, so that the Power spring has a function of suppressing voltage harmonics, but the detection technology cannot simultaneously achieve both harmonic detection precision and dynamic performance of the system.
Disclosure of Invention
Aiming at the problems of Point of Common Coupling (PCC) voltage fluctuation caused by renewable energy power generation grid connection and grid current harmonic and power factor reduction caused by wide application of power electronic devices, the invention aims to provide a power spring multifunctional control method based on a cascade generalized integrator, which can not only transfer the power fluctuation of a grid to a power spring device and a non-critical load, thereby ensuring the stability of the voltage and the power of the critical load; the harmonic wave of the current of the power grid can be inhibited, so that the current waveform of the power grid tends to be more sinusoidal; meanwhile, reactive compensation can be provided for the power grid, so that the power factor of the power grid is improved. Because a low-pass filtering link is not introduced, the control method improves the real-time performance of detection, and the system can obtain better dynamic performance while ensuring the harmonic detection precision.
The invention is realized by at least one of the following technical schemes.
A power spring multifunctional control method based on a cascade generalized integrator comprises the following steps:
1) real-time acquisition of voltage signal u at PCCSCurrent signal i of the critical loadCOutput voltage signal u of power springESAnd power spring internal inductor current signal iL；
2) Voltage outer loop control in which a voltage signal u is appliedSEffective value of (U)SWith a given voltage reference value US_refMaking difference, the difference value is passed through a proportional-integral controller, and its output is fundamental wave active current reference value I of power springES1p；
3) Will voltage signal uSObtaining the angular frequency omega of the PCC voltage through a phase-locked loop; the angular frequency omega and the current signal i of the key load are comparedCInputting the current signals into a quadrature signal generator CGI-OSG formed by a cascade generalized integrator CGI to obtain current signals i with the same amplitude and mutually orthogonalC1αAnd iC1β；
4) Three current signals iC1α、iC1β、iCAnd a current reference value IES1pAn input current control module for forming a current reference signal i of the power springES_ref；
5) Reference signal iES_refSum voltage signal uSAn input voltage control module forming a voltage reference signal u of the power springES_ref；
6) Voltage inner loop control of the voltage reference signal uES_refOutput voltage signal u of power spring actually sampledESMaking a difference, forming an inductive current reference signal i inside the power spring by the difference through a harmonic tracking controller MQPRL_ref；
7) Current inner loop control, in which i isL_refAnd actually sampled power spring internal inductance current signal iLMaking difference, the difference value passes through an inner ring current controller kCAnd forms a modulation wave signal after passing through a limiter;
8) and comparing the modulated wave signal with the triangular carrier signal to obtain a driving signal of the power spring switch tube.
Preferably, in step 2), the transfer function G of the proportional-integral controllerpi(s) is:
Figure BDA0003006572360000031
the output of the proportional-integral controller is:
Figure BDA0003006572360000032
in which s represents a transfer function, kpIs a proportional parameter; k is a radical ofiIs an integral parameter; e is the error value between the PCC voltage reference value and its valid value.
Preferably, in step 3), the cascade generalized integrator CGI includes a second order generalized integrator SOGI and a third order generalized integrator TOGI cascade; angular frequency omega and current signal i of critical loadCFirstly, inputting the current signal to a second-order generalized integrator, wherein the second-order generalized integrator is used for a current signal i of a key loadCFiltering the medium high frequency component to obtain a current signal iCmSaid current signal iCmComprising a current signal iCA fundamental component, a direct current component, and a low frequency component; will current signal iCmInputting the current signal into a third-order generalized integratorCmFiltering the direct current component and the low frequency component to obtain a current signal i with the same amplitude and orthogonal with each otherC1αAnd iC1β(ii) a Wherein iC1αCurrent signal i to critical loadCFundamental component i inC1Same amplitude and same phase, iC1βPhase contrast iC1Lagging by 90 deg. phase angle.
Preferably, the closed loop transfer functions of the quadrature signal generator CGI-OSG formed based on the cascaded generalized integrator CGI are respectively:
Figure BDA0003006572360000041
Figure BDA0003006572360000042
in the formula, F1α(s) corresponding current signal iC1αAnd iCTransfer function between F1β(s) corresponding current signal iC1βAnd iCA transfer function between; f1α(s) and F1β(s) the band-pass filter has the same amplitude-frequency characteristic and is formed by cascading a low-pass filter and a band-pass filter; omegasIs the resonance angular frequency of the cascade generalized integrator; k is the proportional parameter of the cascaded generalized integrator.
Preferably, in step 4), the current control module is used for sending the current signals i with the same amplitude and orthogonal to each otherC1αAnd iC1βCarrying out dq conversion to respectively form current signals IC1pAnd IC1qThe transformation formula is as follows:
Figure BDA0003006572360000043
where C is a transformation matrix, represented as:
Figure BDA0003006572360000044
where ω is the angular frequency of the PCC voltage; t is time; current signal IC1pFundamental wave active current reference value I of power springES1pMaking difference to form reference value I of power grid input active currentS1p(ii) a Current signal IC1pThrough a proportional controller kQThen forming a reference value I of the input reactive current of the power gridS1qThen I isS1qAnd IS1pCarrying out dq inverse transformation to form a power grid input current reference signal iS_refThe transformation formula is as follows:
Figure BDA0003006572360000051
in the formula iS1αFor mains input current iSFundamental wave portion of (i)S1βIs a virtual current iSβFundamental wave portion of (1), C-1Is a transformation matrix, expressed as:
Figure BDA0003006572360000052
will current signal iCAnd iS_refForming a current reference signal i of the power spring after the differenceES_ref。
Preferably, in step 5), the voltage control module refers the current to the signal iES_refImpedance value Z of non-critical loadNCMultiplied by the voltage signal uSAdding to form a voltage reference signal u of the power springES_ref。
Preferably, in step 6), the harmonic tracking controller MQPR employs a multiple quasi-proportional resonant controller, and a transfer function thereof is:
Figure BDA0003006572360000053
in the formula, kpmIs a proportional parameter; k is a radical ofrmIs the resonant gain; omega0Is the resonant frequency; omegacIs the cut-off frequency; and n is the harmonic order.
Preferably, in step 7), the inner loop current controller kCA proportional controller is employed.
Preferably, the triangular carrier signal is a triangular carrier with a frequency of 20kHz and a peak-to-peak value of 2.
Preferably, the power spring comprises an inverter and an LC low-pass filter connected with the inverter, and the direct-current side voltage of the inverter is obtained by a storage battery or obtained by a grid voltage passing through a PWM rectifier and then being connected with an electrolytic capacitor.
Compared with the prior art, the invention has the beneficial effects that:
1. the invention adopts the cascade generalized integrator and the multiple quasi-proportional resonant controller to track the harmonic component of the current of the power grid, and adopts the coordinate transformation mode to perform reactive compensation on the power grid, thereby realizing the multifunctional control of the power spring. The method can not only ensure the voltage stability of the key load, but also effectively inhibit the current harmonic wave of the power grid, so that the current waveform of the power grid tends to be more sinusoidal; and meanwhile, the power factor of the power grid can be improved.
2. The invention does not introduce a low-pass filtering link, improves the real-time performance of detection, and has better dynamic response capability while ensuring the harmonic detection precision.
Drawings
FIG. 1 is a block diagram of the power spring system of the present invention;
FIG. 2 is a control block diagram of the power spring system of the present invention;
FIG. 3 is a block diagram of a structure of a quadrature signal generator CGI-OSG in FIG. 2;
FIG. 4 is a diagram of a model of the structure of the SOGI and the TOGI of FIG. 3;
FIG. 5 is an internal control block diagram of the current control module of FIG. 2;
FIG. 6 is an internal control block diagram of the voltage control module of FIG. 2;
FIG. 7 is a block diagram of the structure of the multi-quasi-proportional resonant controller MQPR of FIG. 2;
FIG. 8a shows the PCC voltage u before and after the power spring is operatedSComparing the simulation waveforms;
FIG. 8b shows the PCC current i before and after the power spring is operatedSComparing the simulation waveforms;
FIG. 8c shows the effective value U of the PCC voltage before and after the power spring is operatedSComparing the simulation waveforms;
FIG. 8d is a comparison graph of simulated power factor PF waveforms of the system before and after the power spring is operated;
FIG. 9 is a graph of harmonic analysis results of PCC current before power spring operation;
FIG. 10 is a graph of harmonic analysis results of PCC current after power spring operation.
Detailed Description
Embodiments of the present invention will be described in further detail with reference to the following drawings and specific examples, but the practice and protection of the present invention are not limited thereto, and it should be noted that the following descriptions are not specifically detailed, and can be realized and understood by those skilled in the art with reference to the prior art.
As shown in FIG. 1, a typical application of an electrical spring includes a voltage source uGLine resistance R1Line inductor L1Critical load ZCNon-critical load ZNCA single phase power spring system; the single-phase power spring system is a second-generation single-phase power spring system and comprises a bidirectional direct-current power supply UdcThe single-phase voltage source type inverter module comprises a single-phase voltage source type inverter module, an LC low-pass filter and a control circuit; common connection point PCC as power spring and critical load ZCAnd line impedance Z1The connection point of (a). In the figure, S1、S2、S3、S44 IGBT switch tubes which are power springs; i.e. iLIs the inductive current of the power spring; i.e. iESIs the output current of the power spring; i.e. iSIs the grid current, i.e. the PCC current; u. ofESIs the output voltage of the power spring; u. ofNCTerminal voltage of a non-critical load; u. ofSIs the terminal voltage of the critical load, i.e., the PCC voltage.
For convenient analysis, the non-critical load adopts pure resistance during simulation, and the critical load adopts current source type non-linear load. Wherein the frequency of the power grid voltage is 50 Hz.
Example 1
As shown in fig. 2, one control cycle of the cascaded generalized integrator-based power spring multi-functionalization control includes the steps of:
1) real-time acquisition of voltage signal u at PCCSCurrent signal i of the critical loadCOutput voltage signal u of power springESAnd power spring internal inductor current signal iL。
2) Voltage outer loop control, in which a voltage reference value U for PCC is setS_refAt 220V, applying a PCC voltage signal uSEffective value of (U)SAnd US_refMaking difference, the difference value is passed through a proportional-integral controller, and its output is fundamental wave active current reference value I of power springES1p. Transfer function G of proportional-integral controllerpi(s) is:
Figure BDA0003006572360000071
the output of the proportional-integral controller is:
Figure BDA0003006572360000081
in the formula, kpTaking 0.1 as a proportional parameter; k is a radical ofiTaking 10 as an integral parameter; e is the error value between the PCC voltage reference value and its valid value.
3) Will voltage signal uSObtaining the angular frequency omega of the PCC voltage through a phase-locked loop; sum ω with the current signal iCInputting the current signals into a quadrature signal generator CGI-OSG formed by a cascade generalized integrator CGI to obtain current signals i with the same amplitude and mutually orthogonalC1αAnd iC1β。
As shown in fig. 3, the cascaded generalized integrator CGI is formed by cascading a second-order generalized integrator SOGI and a third-order generalized integrator TOGI. Angular frequency omega and current signal iCFirstly input into a second-order generalized integrator to form a pair iCFiltering the medium high frequency component to obtain a current signal iCm，iCmIncluding a current signal iCA fundamental component, a direct current component, and a low frequency component; will current signal iCmInputting the current signal into a third-order generalized integratorCmFiltering the direct current component and the low frequency component to obtain a current signal i with the same amplitude and orthogonal with each otherC1αAnd iC1β. Wherein iC1αAnd a current signal iCFundamental component ofiC1Same amplitude and same phase, iC1βPhase contrast iC1Lagging by 90 deg. phase angle.
FIG. 4 shows a diagram of a structural model of SOGI and TOGI, where the angular frequency ω issThe sum current i is two input signals of the SOGI module and the TOGI module together; i.e. i1And i2Is the output signal of the SOGI module; i.e. i1、i2And i3Respectively output signals of the TOGI module; k is a proportional parameter; integral device. With reference to fig. 3, it can be written that the closed-loop transfer functions of the quadrature signal generator formed based on the cascaded generalized integrators are respectively:
Figure BDA0003006572360000082
Figure BDA0003006572360000083
in the formula, F1α(s) corresponding current signal iC1αAnd iCTransfer function between F1β(s) corresponding current signal iC1βAnd iCA transfer function between; f1α(s) and F1β(s) have the same amplitude-frequency characteristics and can be regarded as a band-pass filter formed by cascading a low-pass filter and a band-pass filter; omegasTaking 100 pi rad/s as the resonance angular frequency of the cascade generalized integrator; k is a proportional parameter of the cascade generalized integrator, and a proper k value can enable the cascade generalized integrator to have good current extraction capability and dynamic response capability at the same time, wherein k is 1.
4) Will current signal iC1α、iC1β、iCAnd a current reference value IES1pAn input current control module for forming a current reference signal i of the power springES_ref. As shown in FIG. 5, inside the current control module, first, the current signal i is sentC1αAnd iC1βCarrying out dq conversion to respectively form current signals IC1pAnd IC1qThe transformation formula is as follows:
Figure BDA0003006572360000091
where C is a transformation matrix, represented as:
Figure BDA0003006572360000092
where ω is the angular frequency of the PCC voltage; t is time.
Will IC1pAnd IES1pMaking difference to form reference value I of power grid input active currentS1p(ii) a Current signal IC1pThrough a proportional controller kQThen forming a reference value I of the input reactive current of the power gridS1qWhere k isQTake 0. Then I isS1qAnd IS1pCarrying out dq inverse transformation to form a power grid input current reference signal iS_refThe transformation formula is as follows:
Figure BDA0003006572360000093
in the formula iS1αFor mains input current iSFundamental wave portion of (i)S1βIs a virtual current iSβFundamental wave portion of (1), C-1Is a transformation matrix, expressed as:
Figure BDA0003006572360000101
where ω is the angular frequency of the PCC voltage; t is time.
Will current signal iCAnd iS_refForming a current reference signal i of the power spring after the differenceES_ref；
5) Reference signal iES_refSum voltage signal uSAn input voltage control module forming a voltage reference signal u of the power springES_ref. As shown in FIG. 6, the current reference signal i is generated inside the voltage control moduleES_refAnd non-critical loadsImpedance value Z ofNCMultiplied by the voltage signal uSAdding to form a voltage reference signal u of the power springES_ref。
6) Inner loop control of voltage in which u isES_refAnd the actual sampling voltage uESMaking a difference, forming an inductive current reference signal i inside the power spring by the difference through a harmonic tracking controller MQPRL_ref. The harmonic tracking controller MQPR herein employs a multiple quasi-proportional resonant controller, which is shown in fig. 7, where x and y are input signals and output signals of the multiple quasi-proportional resonant controller, respectively. The transfer function of the multiple quasi-proportional resonant controller is:
Figure BDA0003006572360000102
in the formula, kpmTaking 0.3 as a proportional parameter; k is a radical ofrmFor the resonant gain, take 2.5; omega0Taking 100 pi rad/s as resonance frequency; omegacTaking pi rad/s as a cut-off frequency; and n is the harmonic frequency, 1, 3, 5 and 7 are taken here, and 3, 5 and 7 harmonics in the power grid current are tracked and suppressed.
7) Current inner loop control, in which i isL_refAnd the actual sampling current iLMaking difference, the difference value passes through an inner ring current controller kCAnd forms a modulated wave signal after passing through a limiter. Here the inner loop current controller kCUsing a proportional controller, kCAnd taking 12.
8) And comparing the modulated wave signal with the triangular carrier signal to obtain a driving signal of the power spring switch tube. Specifically, a triangular carrier with the frequency of 20kHz and the peak-to-peak value of 2 is selected for bipolar modulation. The dc side voltage of the power spring inverter was taken to be 400V and obtained from the battery.
Example 2
In embodiment 1, replacing the harmonic tracking controller MQPR in step 6) from the multiple quasi-proportional resonant controller to the quasi-proportional resonant controller may be used as another preferred embodiment. The modified step 6) is specifically expressed as: inner loop control of voltage in which u isES_refAnd the actual sampling voltage uESComparing, forming an inductive current reference signal i inside the power spring by the difference value through a harmonic tracking controller MQPRL_ref. The harmonic tracking controller MQPR uses a quasi-proportional resonant controller, and its transfer function is:
Figure BDA0003006572360000111
in the formula, kpmTaking 0.3 as a proportional parameter; k is a radical ofrmFor the resonant gain, take 2.5; omega0Taking 100 pi rad/s as resonance frequency; omegacFor the cut-off frequency, take π rad/s.
Example 3
In embodiment 1, replacing the harmonic tracking controller MQPR in step 6) with the proportional-integral controller from the multiple quasi-proportional resonant controller can be taken as another preferred embodiment. The modified step 6) is specifically expressed as: inner loop control of voltage in which u isES_refAnd the actual sampling voltage uESComparing, forming an inductive current reference signal i inside the power spring by the difference value through a harmonic tracking controller MQPRL_ref。
The harmonic tracking controller MQPR uses a proportional-integral controller, and its transfer function is:
Figure BDA0003006572360000112
in the formula, kpmTaking 0.25 as a proportional parameter; k is a radical ofimFor the integral gain, 0.5 is taken.
Example 4
In embodiment 1, the switching tube driving signal in step 8) is changed to be obtained by a hysteresis comparator, which can be taken as another preferred embodiment. The modified step 8) is specifically expressed as: and inputting the modulation wave signal into a hysteresis comparator to obtain a driving signal of the power spring switch tube. Here the width of the hysteresis loop in the hysteresis comparator takes 0.07. The dc side voltage of the power spring inverter was taken to be 400V and obtained from the battery.
Example 5
In embodiment 1, the dc-side voltage of the power spring inverter in step 8) is obtained from the storage battery instead of the single-phase grid voltage through the PWM rectifier and then the electrolytic capacitor, which is another preferred embodiment. The modified step 8) is specifically expressed as: and comparing the modulated wave signal with the triangular carrier signal to obtain a driving signal of the power spring switch tube. Specifically, a triangular carrier with the frequency of 20kHz and the peak-to-peak value of 2 is selected for bipolar modulation. The direct-current side voltage of the power spring inverter is 400V, the direct-current side voltage is obtained by connecting a single-phase power grid voltage with an electrolytic capacitor after passing through a PWM rectifier, and the size of the electrolytic capacitor is 20 muF.
In order to verify the effectiveness of the scheme of the invention, a simulation model is built on PLECS software, and a simulation test is carried out by adopting a discrete-time fixed-step simulation mode. The simulation test specifically performs validity verification on embodiment 1, and other embodiments can verify the validity similarly.
The sampling time was 1e-6s, and the component parameters used in the simulation are shown in table 1.
TABLE 1 simulation Components parameters
Figure BDA0003006572360000121
Figure BDA0003006572360000131
As shown in fig. 8a, 8b, 8c and 8d, the system has good dynamic response capability by adopting the power spring multi-functionalization control method based on the cascade generalized integrator. In the figure, the power spring is started at 0.5s, the critical load voltage is stabilized at a reference value of 220V after 0.05s, and the power factor of the power grid is increased from 0.965 to 0.999. Fig. 9 and 10 show that after the power spring works, the harmonic content of the PCC current is reduced from 20.14% to 0.95%, and the national standard is met. The simulation result verifies the effectiveness of the invention.
The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention in any way, but any modifications or equivalent variations made in accordance with the technical spirit of the present invention are within the scope of the present invention as claimed.

Claims (9)

1. A power spring multifunctional control method based on a cascade generalized integrator is characterized by comprising the following steps:
1) real-time acquisition of voltage signal u at PCCSCurrent signal i of the critical loadCOutput voltage signal u of power springESAnd power spring internal inductor current signal iL；
2) Voltage outer loop control in which a voltage signal u is appliedSEffective value of (U)SWith a given voltage reference value US_refMaking difference, the difference value is passed through a proportional-integral controller, and its output is fundamental wave active current reference value I of power springES1p；
3) Will voltage signal uSObtaining the angular frequency omega of the PCC voltage through a phase-locked loop; the angular frequency omega and the current signal i of the key load are comparedCInputting the current signals into a quadrature signal generator CGI-OSG formed by a cascade generalized integrator CGI to obtain current signals i with the same amplitude and mutually orthogonalC1αAnd iC1β；
4) Three current signals iC1α、iC1β、iCAnd a current reference value IES1pAn input current control module for forming a current reference signal i of the power springES_ref(ii) a The current control module is used for enabling current signals i with the same amplitude and mutually orthogonal to each otherC1αAnd iC1βCarrying out dq conversion to respectively form current signals IC1pAnd IC1qThe transformation formula is as follows:
Figure FDA0003466074310000011
where C is a transformation matrix, represented as:
Figure FDA0003466074310000012
where ω is the angular frequency of the PCC voltage; t is time; current signal IC1pFundamental wave active current reference value I of power springES1pMaking difference to form reference value I of power grid input active currentS1p(ii) a Current signal IC1pThrough a proportional controller kQThen forming a reference value I of the input reactive current of the power gridS1qThen I isS1qAnd IS1pCarrying out dq inverse transformation to form a power grid input current reference signal iS_refThe transformation formula is as follows:
Figure FDA0003466074310000021
in the formula iS1αFor mains input current iSFundamental wave portion of (i)S1βIs a virtual current iSβFundamental wave portion of (1), C-1Is a transformation matrix, expressed as:
Figure FDA0003466074310000022
will current signal iCAnd iS_refForming a current reference signal i of the power spring after the differenceES_ref；
5) Reference signal iES_refSum voltage signal uSAn input voltage control module forming a voltage reference signal u of the power springES_ref；
6) Voltage inner loop control of the voltage reference signal uES_refOutput voltage signal u of power spring actually sampledESMaking a difference, forming an inductive current reference signal i inside the power spring by the difference through a harmonic tracking controller MQPRL_ref；
7) Current inner loop control, in which i isL_refAnd actually sampled power spring internal inductance current signal iLMaking difference, the difference value passes through an inner ring current controller kCAnd forms a modulation wave signal after passing through a limiter;
8) and comparing the modulated wave signal with the triangular carrier signal to obtain a driving signal of the power spring switch tube.
2. The cascade generalized integrator-based power spring multi-functionalization control method according to claim 1, wherein in the step 2), a transfer function G of the proportional-integral controllerpi(s) is:
Figure FDA0003466074310000023
the output of the proportional-integral controller is:
Figure FDA0003466074310000024
in which s represents a transfer function, kpIs a proportional parameter; k is a radical ofiIs an integral parameter; e is the error value between the PCC voltage reference value and its valid value.
3. The cascade generalized integrator-based power spring multi-functional control method according to claim 2, wherein in step 3), the cascade generalized integrator CGI comprises a second-order generalized integrator SOGI and a third-order generalized integrator TOGI cascade; angular frequency omega and current signal i of critical loadCFirstly, inputting the current signal to a second-order generalized integrator, wherein the second-order generalized integrator is used for a current signal i of a key loadCFiltering the medium high frequency component to obtain a current signal iCmSaid current signal iCmComprising a current signal iCA fundamental component, a direct current component, and a low frequency component; will current signal iCmInputting the current signal into a third-order generalized integratorCmFiltering the direct current component and the low frequency component to obtain the components with the same amplitude and orthogonal with each otherCurrent signal iC1αAnd iC1β(ii) a Wherein iC1αCurrent signal i to critical loadCFundamental component i inC1Same amplitude and same phase, iC1βPhase contrast iC1Lagging by 90 deg. phase angle.
4. The cascade generalized integrator-based power spring multifunctional control method as claimed in claim 3, wherein the closed loop transfer functions of the orthogonal signal generator CGI-OSG formed based on the cascade generalized integrator CGI are respectively:
Figure FDA0003466074310000031
Figure FDA0003466074310000032
in the formula, F1α(s) corresponding current signal iC1αAnd iCTransfer function between F1β(s) corresponding current signal iC1βAnd iCA transfer function between; f1α(s) and F1β(s) the band-pass filter has the same amplitude-frequency characteristic and is formed by cascading a low-pass filter and a band-pass filter; omegasIs the resonance angular frequency of the cascade generalized integrator; k is the proportional parameter of the cascaded generalized integrator.
5. The cascade generalized integrator-based power spring multi-functionalization control method according to claim 4, wherein in the step 5), the voltage control module is used for converting a current reference signal i into a current reference signal iES_refImpedance value Z of non-critical loadNCMultiplied by the voltage signal uSAdding to form a voltage reference signal u of the power springES_ref。
6. The cascaded generalized integrator-based power spring multifunctional control method as claimed in claim 5, wherein in step 6), the harmonic tracking controller MQPR adopts a multiple quasi-proportional resonant controller, and its transfer function is:
Figure FDA0003466074310000041
in the formula, kpmIs a proportional parameter; k is a radical ofrmIs the resonant gain; omega0Is the resonant frequency; omegacIs the cut-off frequency; and n is the harmonic order.
7. The cascade generalized integrator-based power spring multi-functionalization control method according to claim 6, wherein in step 7), the inner ring current controller kCA proportional controller is employed.
8. The cascaded generalized integrator-based power spring multi-functionalization control method according to claim 7, wherein the triangular carrier signal is a triangular carrier with a frequency of 20kHz and a peak-to-peak value of 2.
9. The cascade generalized integrator-based power spring multi-functionalization control method according to claim 8, wherein the power spring comprises an inverter and an LC low-pass filter connected with the inverter, and the direct-current side voltage of the inverter is obtained by a storage battery or obtained by a grid voltage through a PWM rectifier and then an electrolytic capacitor.
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