CN110311416B - Phase-locked loop bandwidth self-adaptive grid-connected inverter control method based on state feedback - Google Patents

Phase-locked loop bandwidth self-adaptive grid-connected inverter control method based on state feedback Download PDF

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CN110311416B
CN110311416B CN201910516333.2A CN201910516333A CN110311416B CN 110311416 B CN110311416 B CN 110311416B CN 201910516333 A CN201910516333 A CN 201910516333A CN 110311416 B CN110311416 B CN 110311416B
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grid
pll
locked loop
coordinate system
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CN110311416A (en
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张兴
李明
张军军
董玮
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State Grid Corp of China SGCC
China Electric Power Research Institute Co Ltd CEPRI
Hefei University of Technology
Electric Power Research Institute of State Grid Jiangsu Electric Power Co Ltd
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State Grid Corp of China SGCC
China Electric Power Research Institute Co Ltd CEPRI
Hefei University of Technology
Electric Power Research Institute of State Grid Jiangsu Electric Power Co Ltd
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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
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
    • H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
    • H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/53—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M7/537—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
    • H02M7/5387—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration

Abstract

The invention discloses a phase-locked loop bandwidth self-adaptive grid-connected inverter control method based on state feedback. Aiming at the problem that the stability margin of the grid-connected inverter is reduced and even unstable under the condition of a weak power grid, the invention detects the harmonic amplitude of the low frequency band of the grid-connected inverter through the discrete Fourier algorithm to adaptively adjust the bandwidth of a phase-locked loop of the grid-connected inverter while realizing the low-frequency resonance of the grid-connected inverter through the state feedback control based on differential negative feedback, thereby further ensuring the phase margin of the grid-connected inverter under the weak power grid and improving the power grid adaptability of the grid-connected inverter.

Description

Phase-locked loop bandwidth self-adaptive grid-connected inverter control method based on state feedback
Technical Field
The invention relates to a control method of a grid-connected inverter system, in particular to a phase-locked loop bandwidth self-adaptive grid-connected inverter control method based on state feedback.
Background
With the rapid development of distributed power generation systems, grid-connected inverters are widely used. Under the condition of a weak power grid with high impedance, a dynamic interconnection system can be formed between the inverter and the power grid, so that the bandwidth of a control system of the grid-connected inverter is reduced, and the control stability of the control system is influenced.
In weak grid conditions, the scheme of increasing the control loop to achieve the purpose of weakening or suppressing the resonance is called as an active damping scheme, and the pole position of the closed-loop system is configured to stabilize the system usually by feeding back all or part of state variables to the forward channel of the inverter, and such methods can be unified with the pole configuration of state feedback control, for example: chinese patent document CN 103326386B issued on 17.6.2015, "an active damping method for a grid-connected inverter based on capacitor voltage", is to suppress the resonance of the LCL filter by setting an active damping link based on capacitor voltage. For the LCL filter, the proportion coefficient and the differential order of the active damping link are selected, so that the sufficient damping for the resonance suppression of the LCL filter is ensured. However, the problem of resonance of the grid-connected inverter LCL type filter is considered in the article, and the problem of how to improve the stability margin through active damping in the case of weak grid is not considered; in addition, when the impedance of the power grid is large, the characteristic of the controlled object is changed by adopting state feedback, and the pole of the system with low frequency close to instability cannot be moved to the left half plane, so that the system is stable.
In addition, under a weak power grid, the stability of the grid-connected inverter can be improved by reducing the bandwidth of the phase-locked loop, for example: wuheng, Ruan Xinbo and Yang Dongsheng are published in 2014 10, 25 th and 34 th periods of Chinese Motor engineering Proc, 30 th of "research on influence of phase-locked loop on stability of LCL type grid-connected inverter under weak grid condition and design of phase-locked loop parameters", the article designs parameters of the phase-locked loop according to phase angle margin requirements, and enhances adaptability of the inverter to different grid impedances under a current source mode by changing bandwidth of the phase-locked loop, but the method greatly reduces rapidity of phase locking of the grid-connected inverter and is not suitable for occasions with high dynamic performance requirements.
In summary, the prior art has the following problems:
(1) for the weak grid condition, the existing literature adopts a grid-connected inverter active damping method based on capacitance voltage to realize state feedback, but when the grid impedance is large, the state feedback is adopted to change the characteristic of a controlled object, so that the low-frequency unstable pole of the system can not be moved to the left half plane, and the stability margin of the system can be improved;
(2) in the existing grid-connected inverter control scheme under the weak grid, the problem that the grid-connected stability of the inverter is realized through a phase-locked loop bandwidth self-adaptive scheme based on state feedback is not involved.
Disclosure of Invention
In order to overcome the limitations of various technical schemes, aiming at the problem that the stability margin of the grid-connected inverter is reduced and even unstable under the condition of a weak power grid, the method for controlling the phase-locked loop bandwidth self-adaptive grid-connected inverter based on state feedback is provided.
The object of the invention is thus achieved. The invention provides a phase-locked loop bandwidth self-adaptive grid-connected inverter control method based on state feedback, which comprises the following steps of:
step 1, collecting and outputting grid-connected current iga、igb、igcAnd a capacitor voltage uca、ucb、ucc；
Step 2, according to the capacitance voltage u collected in the step 1ca、ucb、uccObtaining voltage dq of the point of common coupling through a transformation equation from a three-phase static coordinate system to a two-phase rotating coordinate systemAxial component ucd1、ucq1(ii) a The capacitor voltage uca、ucb、uccObtaining a voltage phase angle theta of a public coupling point through phase locking of a phase-locked loop (PLL);
the transformation equation from the three-phase stationary coordinate system to the two-phase rotating coordinate system is as follows:
Figure BDA0002095158390000021
Figure BDA0002095158390000022
the formula for the calculation of the phase angle θ is:
Figure BDA0002095158390000023
wherein ω is0Rated angular frequency, K, of voltage at point of common couplingp_PLLFor adjusting the coefficient of proportionality, K, of phase-locked loop regulatorsi_PLLIntegrating and adjusting coefficients for a phase-locked loop regulator, wherein s is a Laplace operator;
step 3, converting the output grid-connected current i acquired in the step 1 into a two-phase rotating coordinate system through a three-phase static coordinate system according to the voltage phase angle theta acquired in the step 2ga、igb、igcConverting the output grid-connected current dq component i under a two-phase rotating coordinate systemgdAnd igq；
The transformation equation of the output grid-connected current from the three-phase static coordinate system to the two-phase rotating coordinate system is as follows:
Figure BDA0002095158390000031
Figure BDA0002095158390000032
step 4, setting and outputting a grid-connected current command signal igdref，igqref(ii) a According to the output grid-connected current dq component i obtained in the step 3gdAnd igqObtaining an output signal u of the PI regulator through a power grid current closed-loop control equationdAnd uq；
The closed-loop control equation of the power grid current is as follows:
ud＝(kp+ki/s)·(igdref-igd)
uq＝(kp+ki/s)·(igqref-igq)
k in the formulapIs a proportional control coefficient, k, of a current loop PI regulatoriThe integral control coefficient of the current loop PI regulator is obtained;
step 5, according to the public coupling point voltage dq axis component u obtained in the step 2cd1、ucq1Obtaining a feedback dq component u through a state feedback link equation based on differential negative feedbackcd2、ucq2(ii) a And then according to the PI regulator output signal u obtained in the step 4dAnd uqSubtracting the feedback dq components u, respectivelycd2、ucq2To obtain a control signal ud1、uq1；
The state feedback link equation based on differential negative feedback is as follows:
Figure BDA0002095158390000033
Figure BDA0002095158390000034
omega in the formularResonant frequency, K, being a differential negative feedback elementmThe differential negative feedback is a proportionality coefficient of the grid-connected inverter, and n is a differential order of the differential negative feedback of the grid-connected inverter;
control signal ud1、uq1The calculation formula of (A) is as follows:
ud1＝ud-ucd2
uq1＝uq-ucq2
step 6, according to the voltage phase angle theta of the point of common coupling obtained in step 2, carrying out the stepControl signal u obtained in step 5d1、uq1Converting the control signal component u into a control signal component u under a three-phase static coordinate system through a transformation equation from a two-phase rotating coordinate system to the three-phase static coordinate systema、ub、uc；
The transformation equation from the two-phase rotating coordinate system to the three-phase stationary coordinate system is:
ua＝ud1cosθ-uq1sinθ
Figure BDA0002095158390000041
Figure BDA0002095158390000042
step 7, according to the control signal component u under the three-phase static coordinate system obtained in the step 6a、ub、ucAnd generating a switching signal of the inverter power device through SPWM modulation, and controlling the on-off of the three-phase full-bridge inverter power device through a driving protection circuit.
Preferably, the phase-locked loop regulator scaling factor K of step 2p_PLLAnd the integral regulating coefficient K of the phase-locked loop regulatori_PLLThe setting steps are as follows:
step 2.1, setting a proportionality coefficient K of differential negative feedback of the grid-connected invertermThe differential order n of differential negative feedback of the grid-connected inverter, the harmonic content critical value A of the 11 th order of the public coupling point and the harmonic component content critical value B of the public coupling point 13; giving initial parameters of a phase-locked loop regulator, wherein the initial parameters of the phase-locked loop regulator comprise an initial scaling coefficient K of the phase-locked loop regulatorp_pll' and phase-locked loop regulator initial integral parameter Ki_pll’；
Step 2.2, sampling 11-th harmonic content h of current of a public coupling point of the grid-connected inverter11And 13 th harmonic content h13；
Step 2.3, judging whether the conditions are met: h is11<A and h13<B；
If the initial parameters are met, keeping the initial parameters of the phase-locked loop regulator unchanged, namely:
Kp_PLL＝Kp_pll’
Ki_PLL＝Ki_pll’
if not, adjusting the value of the initial parameter of the phase-locked loop regulator, namely:
Kp_PLL<Kp_pll’
Ki_PLL<Ki_pll’。
compared with the prior art, the invention has the beneficial effects that:
1. according to the invention, through state feedback control based on differential feedback and adaptive adjustment of proportion and integral parameters of the phase-locked loop regulator according to the contents of 11 th harmonic waves and 13 th harmonic waves of grid-connected current, the adaptive adjustment of the bandwidth of the phase-locked loop is realized, and the stability of the inverter is improved;
2. the invention improves the problem that the impedance change of a large-range power grid cannot be adapted to by adopting single differential negative feedback or phase-locked loop regulation, improves the stability of the grid-connected inverter under a weak power grid, and increases the power grid adaptability of the grid-connected inverter;
3. the invention realizes the stable control of the grid-connected inverter under the weak power grid by adding the differential negative feedback of the capacitor voltage and adjusting the proportion and integral parameters of the phase-locked loop, and the realization mode is simple, convenient and effective.
Drawings
Fig. 1 is a schematic control structure diagram of a phase-locked loop bandwidth adaptive grid-connected inverter control method based on state feedback.
FIG. 2 shows the proportional and integral adjustment coefficients and the proportional coefficient K of the differential negative feedback of the phase-locked loop regulatormAnd a setting step of the differential order n.
Fig. 3 shows a waveform of a-phase output grid-connected current before the present invention is applied.
Fig. 4 is a harmonic spectrum diagram of a phase a output grid-connected current before the present invention is applied.
Fig. 5 shows a waveform of a-phase output grid-connected current after the present invention is applied.
Fig. 6 is a harmonic spectrum diagram of a phase a output grid-connected current before the present invention is applied.
Detailed Description
The embodiment of the invention provides a phase-locked loop bandwidth self-adaptive grid-connected inverter control method based on state feedback, which aims to solve the problem that the grid-connected inverter has reduced stability margin and even is unstable under the condition of a weak power grid in the prior art.
The technical scheme of the invention is clearly and completely described below with reference to the accompanying drawings.
The control structure schematic diagram of the phase-locked loop bandwidth self-adaptive grid-connected inverter control method based on state feedback is shown in fig. 2. The grid-connected topology structure of the grid-connected inverter in fig. 2 comprises a three-phase bridge type inversion topology and an inverter side inductor L1Filter capacitor C and damping resistor RdGrid side inductor L2LCL type filter passes through PCC and has grid impedance LgThe three-phase public power grid is connected.
In the present embodiment, L1＝0.9mH，C＝40μF，Rd＝0.15Ω，L2＝0.1mH，Lg＝2.4mH。
The invention comprises the following steps:
step 1, collecting and outputting grid-connected current iga、igb、igcAnd a capacitor voltage uca、ucb、ucc。
Step 2, according to the capacitance voltage u collected in the step 1ca、ucb、uccObtaining the voltage dq axis component u of the point of common coupling through a transformation equation from a three-phase static coordinate system to a two-phase rotating coordinate systemcd1、ucq1(ii) a The capacitor voltage uca、ucb、uccAnd obtaining a voltage phase angle theta of the common coupling point through phase locking of a phase-locked loop (PLL).
The transformation equation from the three-phase stationary coordinate system to the two-phase rotating coordinate system is as follows:
Figure BDA0002095158390000061
Figure BDA0002095158390000062
the formula for the calculation of the phase angle θ is:
Figure BDA0002095158390000063
wherein ω is0Rated angular frequency, K, of voltage at point of common couplingp_PLLFor adjusting the coefficient of proportionality, K, of phase-locked loop regulatorsi_PLLFor the phase-locked loop regulator integral adjustment coefficient, s is the laplacian operator. In the present embodiment, ω0＝314rad/s。
Step 3, converting the output grid-connected current i acquired in the step 1 into a two-phase rotating coordinate system through a three-phase static coordinate system according to the voltage phase angle theta acquired in the step 2ga、igb、igcConverting the output grid-connected current dq component i under a two-phase rotating coordinate systemgdAnd igq；
The transformation equation of the output grid-connected current from the three-phase static coordinate system to the two-phase rotating coordinate system is as follows:
Figure BDA0002095158390000064
step 4, setting and outputting a grid-connected current command signal igdref，igqref(ii) a According to the output grid-connected current dq component i obtained in the step 3gdAnd igqObtaining a PI output signal u through a power grid current closed-loop control equationdAnd uq；
The closed-loop control equation of the power grid current is as follows:
ud＝(kp+ki/s)·(igdref-igd)
uq＝(kp+ki/s)·(igqref-igq)
k in the formulapIs a proportional control coefficient, k, of a current loop PI regulatoriThe control coefficient is integrated by the current loop PI regulator. In the present embodiment, kp＝210，ki＝2800。
Step 5, according to the public coupling point voltage dq axis component u obtained in the step 2cd1、ucq1Obtaining feedback dq components u through a state feedback link equation based on differential negative feedbackcd2、ucq2(ii) a And then according to the PI regulator output signal u obtained in the step 4dAnd uqSubtracting the feedback dq components u, respectivelycd2、ucq2To obtain a control signal ud1、uq1。
The state feedback link equation based on differential negative feedback is as follows:
Figure BDA0002095158390000071
Figure BDA0002095158390000072
omega in the formularResonant frequency, K, being a differential negative feedback elementmIs the proportionality coefficient of the differential negative feedback of the grid-connected inverter, and n is the differential order of the differential negative feedback of the grid-connected inverter. In this embodiment, Km＝1，n＝1。
Control signal ud1、uq1The calculation formula of (A) is as follows:
ud1＝ud-ucd2
uq1＝uq-ucq2
step 6, according to the voltage phase angle theta of the point of common coupling obtained in the step 2, the control signal u obtained in the step 5 is usedd1、uq1Through two-phase rotating seatConverting the transformation equation from the standard system to the three-phase static coordinate system into a control signal component u under the three-phase static coordinate systema、ub、uc。
The transformation equation from the two-phase rotating coordinate system to the three-phase stationary coordinate system is:
ua＝ud1cosθ-uq1sinθ
Figure BDA0002095158390000075
Figure BDA0002095158390000074
step 7, obtaining the component u under the three-phase static coordinate system according to the step 6a、ub、ucSwitching signals of the inverter power device are generated through SPWM modulation, and the three-phase full-bridge inverter power device is controlled to be switched on and switched off through the driving protection circuit.
FIG. 2 shows the steps for setting the scaling factor and integral factor of the phase-locked loop regulator according to the invention, from which it can be seen that step 2 shows the phase-locked loop regulator scaling factor Kp_PLLAnd the integral regulating coefficient K of the phase-locked loop regulatori_PLLThe setting steps are as follows:
step 2.1, setting a proportionality coefficient K of differential negative feedback of the grid-connected invertermThe differential order n of differential negative feedback of the grid-connected inverter, the harmonic content critical value A of the 11 th order of the public coupling point and the harmonic component content critical value B of the public coupling point 13; giving initial parameters of a phase-locked loop regulator, wherein the initial parameters of the phase-locked loop regulator comprise an initial scaling coefficient K of the phase-locked loop regulatorp_pll' and phase-locked loop regulator initial integral parameter Ki_pll’。
In this embodiment, Km＝1，n＝1，A＝3％，B＝1.5％，Kp_pll’＝2000，Ki_pll’＝1。
Step 2.2, sampling 11-th harmonic content h of current of a public coupling point of the grid-connected inverter11And 13 th harmonic content h13；
Step 2.3, judging whether the conditions are met: h is11<A and h13<B；
If the initial parameters are met, keeping the initial parameters of the phase-locked loop regulator unchanged, namely:
Kp_PLL＝Kp_pll’
Ki_PLL＝Ki_pll’
if not, adjusting the value of the initial parameter of the phase-locked loop regulator, namely:
Kp_PLL<Kp_pll’
Ki_PLL<Ki_pll’。
the amplitude of the adjustment is: 0.1Kp_pll’≤Kp_PLL≤0.5Kp_pll’，0.1Ki_pll’≤Kp_PLL≤0.5Ki_pll'. In this embodiment, let Kp_pll’＝2000，Ki_pll' 1, after adjustment, take Kp_pll＝200，Ki_pll＝0.1。
Fig. 3 and 4 show the waveform of the a-phase output grid-connected current and the harmonic frequency spectrum thereof respectively before the invention is adopted. As can be seen from fig. 3 and 4, before the present invention is adopted, the output grid-connected current has obvious resonance phenomenon, and the total harmonic distortion rate THD is 11.6%. And, 11 th harmonic content h113.2%, 13 th harmonic content h13Is 1.6%, therefore h11>A is 3% and h13>And B is 1.5 percent. The control algorithm of the present invention will now be implemented according to the steps in a specific embodiment of the present invention. Fig. 5 and fig. 6 show the waveform of the a-phase output grid-connected current and the harmonic frequency spectrum thereof respectively after the invention is adopted. As can be seen from fig. 5 and 6, before the present invention is adopted, the output grid-connected current waveform has no obvious resonance phenomenon, and the total harmonic distortion rate THD is reduced to 1.9%.
As can be seen from fig. 3, fig. 4, fig. 5 and fig. 6, the phase-locked loop bandwidth adaptive grid-connected inverter control method based on state feedback of the present invention can effectively ensure the stability of the grid-connected inverter in a weak grid, and improve the grid adaptability of the grid-connected inverter.

Claims (2)

1. A phase-locked loop bandwidth self-adaptive grid-connected inverter control method based on state feedback is characterized by comprising the following steps:
step 1, collecting and outputting grid-connected current iga、igb、igcAnd a capacitor voltage uca、ucb、ucc；
Step 2, according to the capacitance voltage u collected in the step 1ca、ucb、uccObtaining the voltage dq axis component u of the point of common coupling through a transformation equation from a three-phase static coordinate system to a two-phase rotating coordinate systemcd1、ucq1(ii) a The capacitor voltage uca、ucb、uccObtaining a voltage phase angle theta of a public coupling point through phase locking of a phase-locked loop (PLL);
the transformation equation from the three-phase stationary coordinate system to the two-phase rotating coordinate system is as follows:
Figure FDA0002520547100000011
Figure FDA0002520547100000012
the formula for the calculation of the phase angle θ is:
Figure FDA0002520547100000013
wherein ω is0Rated angular frequency, K, of voltage at point of common couplingp_PLLFor adjusting the coefficient of proportionality, K, of phase-locked loop regulatorsi_PLLIntegrating and adjusting coefficients for a phase-locked loop regulator, wherein s is a Laplace operator;
step 3, converting the output grid-connected current i acquired in the step 1 into a two-phase rotating coordinate system through a three-phase static coordinate system according to the voltage phase angle theta acquired in the step 2ga、igb、igcConverting the output grid-connected current dq component i under a two-phase rotating coordinate systemgdAnd igq；
The transformation equation of the output grid-connected current from the three-phase static coordinate system to the two-phase rotating coordinate system is as follows:
Figure FDA0002520547100000014
Figure FDA0002520547100000015
step 4, setting and outputting a grid-connected current command signal igdref，igqref(ii) a According to the output grid-connected current dq component i obtained in the step 3gdAnd igqObtaining an output signal u of the PI regulator through a power grid current closed-loop control equationdAnd uq；
The closed-loop control equation of the power grid current is as follows:
ud＝(kp+ki/s)·(igdref-igd)
uq＝(kp+ki/s)·(igqref-igq)
k in the formulapIs a proportional control coefficient, k, of a current loop PI regulatoriThe integral control coefficient of the current loop PI regulator is obtained;
step 5, according to the public coupling point voltage dq axis component u obtained in the step 2cd1、ucq1Obtaining a feedback dq component u through a state feedback link equation based on differential negative feedbackcd2、ucq2(ii) a And then according to the PI regulator output signal u obtained in the step 4dAnd uqSubtracting the feedback dq components u, respectivelycd2、ucq2To obtain a control signal ud1、uq1；
The state feedback link equation based on differential negative feedback is as follows:
Figure FDA0002520547100000021
Figure FDA0002520547100000022
omega in the formularResonant frequency, K, being a differential negative feedback elementmThe differential negative feedback is a proportionality coefficient of the grid-connected inverter, and n is a differential order of the differential negative feedback of the grid-connected inverter;
control signal ud1、uq1The calculation formula of (A) is as follows:
ud1＝ud-ucd2
uq1＝uq-ucq2
step 6, according to the voltage phase angle theta of the point of common coupling obtained in the step 2, the control signal u obtained in the step 5 is usedd1、uq1Converting the control signal component u into a control signal component u under a three-phase static coordinate system through a transformation equation from a two-phase rotating coordinate system to the three-phase static coordinate systema、ub、uc；
The transformation equation from the two-phase rotating coordinate system to the three-phase stationary coordinate system is:
ua＝ud1cosθ-uq1sinθ
Figure FDA0002520547100000023
Figure FDA0002520547100000024
step 7, according to the control signal component u under the three-phase static coordinate system obtained in the step 6a、ub、ucAnd generating a switching signal of the inverter power device through SPWM modulation, and controlling the on-off of the three-phase full-bridge inverter power device through a driving protection circuit.
2. The phase-locked loop bandwidth adaptive grid-connected inverter control method based on state feedback as claimed in claim 1, wherein the phase-locked loop regulator scaling factor K in step 2p_PLLAnd the integral regulating coefficient of the phase-locked loop regulatorKi_PLLThe setting steps are as follows:
step 2.1, setting a proportionality coefficient K of differential negative feedback of the grid-connected invertermThe differential order n of differential negative feedback of the grid-connected inverter, the content critical value A of 11 subharmonic waves of the public coupling point and the content critical value B of 13 subharmonic waves of the public coupling point; giving initial parameters of a phase-locked loop regulator, wherein the initial parameters of the phase-locked loop regulator comprise an initial scaling coefficient K of the phase-locked loop regulatorp_pll' and phase locked loop regulator initial integral coefficient Ki_pll’；
Step 2.2, sampling 11-th harmonic content h of current of a public coupling point of the grid-connected inverter11And 13 th harmonic content h13；
Step 2.3, judging whether the conditions are met: h is11<A and h13<B；
If the initial parameters are met, keeping the initial parameters of the phase-locked loop regulator unchanged, namely:
Kp_PLL＝Kp_pll’
Ki_PLL＝Ki_pll’
if not, adjusting the value of the initial parameter of the phase-locked loop regulator, namely:
Kp_PLL<Kp_pll’
Ki_PLL<Ki_pll’。
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