CN-121984083-A - Grid-connected inverter optimization compensation method for inhibiting phase-locked loop influence and broadband resonance

CN121984083ACN 121984083 ACN121984083 ACN 121984083ACN-121984083-A

Abstract

The application belongs to the technical field of power electronics, and particularly discloses an optimized compensation method for a grid-connected inverter, which is used for inhibiting the influence of a phase-locked loop and broadband resonance. According to the method, the disturbance transfer function is calculated based on a dynamic model of the phase-locked loop, the related compensation signal is injected into the target shaft signal, low-frequency-band control disturbance dynamically introduced by the phase-locked loop is counteracted, the output compensation signal is superimposed to the related compensation signal, and the output impedance characteristic of the grid-connected inverter in the middle-high frequency band is remolded according to the composite compensation signal. According to the mode, the low-frequency disturbance introduced by the phase-locked loop dynamically is counteracted by adopting the compensation signal which is injected in the mode, an optimized compensation link is additionally arranged on the basis, and the cooperative promotion of the low-frequency stability and the medium-high frequency resonance inhibition of the inverter on the basis of not changing the phase-locked loop structure and main control parameters is realized on the basis of the output compensation signal remodelling in the medium-high frequency band, so that the stability and the electric energy quality of a wide frequency band of a grid-connected system under the weak current network condition are further effectively enhanced.

Inventors

TIAN YE
SHANG LEI
LIU FEI
GU TAIYU
ZHU YIDONG
SHI KEJIAN
DU WEI
LI HAIFENG
LIU ZHAOCHEN

Assignees

国网辽宁省电力有限公司电力科学研究院
武汉大学

Dates

Publication Date: 20260505
Application Date: 20260122

Claims (10)

1. A grid-connected inverter optimization compensation method for inhibiting phase-locked loop influence and broadband resonance is characterized by comprising the following steps: calculating a disturbance transfer function introduced to the current control loop and the modulation voltage link by the voltage disturbance of the public coupling point based on a dynamic model of the phase-locked loop, and determining a compensation signal associated with the disturbance transfer function and the current working point; injecting the associated compensation signal into a target axis signal, and counteracting low-frequency-band control disturbance dynamically introduced by a phase-locked loop through the compensation signal in the target axis signal; Obtaining a compensation signal output by a newly added optimized compensation link, and adding the output compensation signal to the associated compensation signal to obtain a composite compensation signal; and remolding the output impedance characteristic of the grid-connected inverter in the medium-high frequency band according to the composite compensation signal.
2. The method of claim 1, wherein the step of calculating a disturbance transfer function introduced by the point of common coupling voltage disturbance to the current control loop and the modulation voltage link based on the dynamic model of the phase locked loop comprises: Acquiring the voltage and the current of a target control system; Determining grid-connected voltage of the grid-connected inverter according to the voltage and the grid-connected current of the grid-connected inverter according to the current based on a voltage-current approximation strategy; acquiring a target axis component disturbance of the public coupling point voltage; and calculating disturbance transfer functions introduced into the current control loop and the modulation voltage link by the public coupling point voltage disturbance according to the grid-connected voltage, the grid-connected current, the target axis component disturbance and an axis vector conversion strategy based on a dynamic model of the phase-locked loop.
3. The method of claim 2, wherein the steps of determining a grid-tie voltage of the grid-tie inverter from the voltage based on a voltage-current approximation strategy, and determining a grid-tie current of the grid-tie inverter from the current comprise: determining grid-connected current shaft current of the grid-connected inverter under a steady-state condition according to the current; acquiring the current value of the parasitic resistance in the filter inductor; when the current value is not a preset value, isolating the parasitic resistance, and determining a relation equation satisfied by the grid-connected voltage of the grid-connected inverter according to the voltage; determining grid-connected target shaft current according to the state of a unit power factor of grid-connected inverter operation; obtaining grid-connected current of the grid-connected inverter according to the current axis current of the grid connection and the target axis current of the grid connection, and determining grid-connected voltage of the grid-connected inverter according to a relation equation and a modulation voltage which are met by the grid-connected voltage.
4. The method of claim 1, wherein the steps of obtaining the compensation signal output by the newly added optimization compensation element and adding the output compensation signal to the associated compensation signal to obtain a composite compensation signal comprise: Acquiring an analysis result of the current impedance stability, and determining a modulation voltage channel introduced into a branch according to the analysis result; Introducing a phase compensation branch corresponding to a newly added optimization compensation link into the modulation voltage channel; determining a compensation center angular frequency according to the natural resonant frequency of a target filter of the grid-connected inverter and a middle-high frequency resonant band of a control loop, and constructing a transfer function of an optimization compensation link according to the compensation center angular frequency, the Laplacian operator and a phase compensation coefficient; And obtaining a compensation signal output by a newly added optimization compensation link according to the transfer function of the phase compensation branch and the optimization compensation link, and overlapping the output compensation signal to the associated compensation signal to obtain a composite compensation signal.
5. The method of claim 1, wherein the step of reshaping the output impedance characteristics of the grid-tied inverter at the mid-high frequency band based on the composite compensation signal comprises: inputting the composite compensation signal to a target control system; acquiring an additional equivalent admittance corresponding to the composite compensation signal output by the target control system according to a multidimensional transfer function, and calculating an additional output impedance according to the additional equivalent admittance; acquiring an original equivalent admittance, and calculating an original output impedance according to the original equivalent admittance; And remolding the output impedance characteristic of the grid-connected inverter in the middle-high frequency band according to the additional output impedance and the original output impedance.
6. The method of any one of claims 1 to 5, further comprising, after the step of reshaping the output impedance characteristics of the grid-tie inverter at the mid-high frequency band based on the composite compensation signal: constructing an equivalent single-input single-output impedance model of the grid-connected inverter; Based on the equivalent single-input single-output impedance model, calculating phase margin of the target control system under different active power and reactive power working points according to inversion equivalent impedance and grid impedance respectively; And drawing a stable operation feasible region according to the phase margin, and evaluating the safe operation boundary of the grid-connected inverter according to the stable operation feasible region.
7. A grid-connected inverter optimization compensation device for suppressing phase-locked loop effects and broadband resonance, comprising: The determining module is used for calculating a disturbance transfer function which is introduced to the current control loop and the modulation voltage link by the voltage disturbance of the public coupling point based on a dynamic model of the phase-locked loop, and determining a compensation signal associated with the disturbance transfer function and the current working point; the injection module is used for injecting the associated compensation signal into the target axis signal and counteracting the low-frequency-band control disturbance dynamically introduced by the phase-locked loop through the compensation signal in the target axis signal; The superposition module is used for acquiring a compensation signal output by a newly added optimization compensation link, and superposing the output compensation signal to the associated compensation signal to obtain a composite compensation signal; and the remolding module is used for remolding the output impedance characteristic of the grid-connected inverter in the middle-high frequency band according to the composite compensation signal.
8. An electronic device, comprising: at least one memory for storing a computer program; at least one processor for executing the memory-stored program, which processor is adapted to perform the method according to any of claims 1-6 when the memory-stored program is executed.
9. A computer readable storage medium storing a computer program, characterized in that the computer program, when run on a processor, causes the processor to perform the method according to any one of claims 1-6.
10. A computer program product, characterized in that the computer program product, when run on a processor, causes the processor to perform the method according to any of claims 1-6.

Description

Grid-connected inverter optimization compensation method for inhibiting phase-locked loop influence and broadband resonance Technical Field The application belongs to the technical field of power electronics, and particularly relates to a grid-connected inverter optimization compensation method for inhibiting phase-locked loop influence and broadband resonance. Background Along with the large-scale access of the new energy power generation device, the power system gradually presents the characteristics of weak power network such as high power electronic equipment occupation ratio, increased power network equivalent impedance, reduced system strength and the like. Under the condition of weak current network, the interaction between the grid-connected inverter and the power grid is obviously enhanced, the problems of low-frequency oscillation and wide-frequency harmonic resonance are easily caused, and the stable operation and the output power quality of the grid-connected system are seriously affected. In a control system of a grid-connected inverter, a phase-locked loop is used for acquiring phase and frequency information of grid voltage, which is a key link for realizing synchronous grid-connected control, but the phase-locked loop has dynamic characteristics, and the output phase of the phase-locked loop cannot track the phase of the grid voltage accurately in real time under disturbance conditions, so that deviation is generated between a control coordinate system and a system actual coordinate system, and additional disturbance is introduced in links such as grid-connected current control, modulation voltage generation and the like. The additional disturbance is particularly obvious under the condition of weak power grid, and is expressed as that the output impedance of the grid-connected inverter presents negative resistance characteristic in a low frequency band, so that the stability margin of the system is reduced, and even oscillation instability is caused. In order to suppress adverse effects caused by the phase-locked loop, at present, a common way is to improve system stability by directly reducing the bandwidth of the phase-locked loop, changing the phase-locked loop structure, or introducing additional active damping. However, the method has the following defects that firstly, dynamic response performance is obviously sacrificed by reducing the bandwidth of the phase-locked loop to improve stability, secondly, the phase-locked loop or the main control structure is changed, the design complexity of a control system is increased, the engineering applicability is reduced, thirdly, the method based on small signal disturbance compensation is effective only in a low frequency band, the medium-high frequency harmonic suppression capability is limited, and the broadband stability improvement is difficult to realize. Therefore, the above-mentioned method cannot realize the cooperative improvement of the low-frequency stability and the mid-high frequency resonance suppression of the inverter without changing the phase-locked loop structure and the main control parameters. Disclosure of Invention Aiming at the defects of the prior art, the application aims to provide an optimized compensation method for a grid-connected inverter for inhibiting the influence of a phase-locked loop and broadband resonance, and aims to solve the problem that the cooperative promotion of the low-frequency stability and the medium-high frequency resonance inhibition of the inverter cannot be realized on the basis of not changing the phase-locked loop structure and main control parameters due to the direct reduction of the bandwidth of the phase-locked loop, the change of the phase-locked loop structure or the introduction of additional active damping in the prior art. In order to achieve the above object, in a first aspect, the present application provides a grid-connected inverter optimization compensation method for suppressing the influence of a phase-locked loop and broadband resonance, including: calculating a disturbance transfer function introduced to the current control loop and the modulation voltage link by the voltage disturbance of the public coupling point based on a dynamic model of the phase-locked loop, and determining a compensation signal associated with the disturbance transfer function and the current working point; injecting the associated compensation signal into a target axis signal, and counteracting low-frequency-band control disturbance dynamically introduced by a phase-locked loop through the compensation signal in the target axis signal; Obtaining a compensation signal output by a newly added optimized compensation link, and adding the output compensation signal to the associated compensation signal to obtain a composite compensation signal; and remolding the output impedance characteristic of the grid-connected inverter in the medium-high frequency band according to the composite compensation si